Descripting e⁺ and Weyl fermion as beam/current for pump/injection semiconductor devices

The present research deals with other corpuscle types of current injection, such as antimatter and implementation of positron beams with techniques for the generation of electricity to be injected or pumped into semiconductor devices, such as optical emitters (lasers) and detectors (solar-blind Schottky photodiodes). Electricity is generated when negative charges flow between points. However, could we generate what we know as electricity if positive positrons replaced these electrons? If protons were created to flow, would they also produce electricity? The positrons are to be a toroidal form of concentrated energy rather than a monopole point-charge.¹ For example, using semiconductors with e⁺ current injection leads to a different conception of electricity and the current beam’s dynamic nature.

Positrons are subatomic particles, which are the antiparticles of electrons. They have the same mass as electrons but carry a positive electric charge. High-energy photons are produced as a result of the annihilation that occurs when a positron and an electron collide. Positrons were first predicted by Paul Dirac in 1928, and their existence was confirmed by Anderson in 1932. Since then, positrons have undergone significant research in particle physics experiments and have been essential for the construction of the standard model of particle physics. Generating electric current using positrons is an important topic, which is still in the experimental stage. When a positron comes into contact with an electron, they annihilate each other and produce gamma rays. Case 1: If the antimatter atoms are completely isolated, their behavior is identical in every way to the equivalent matter atoms. Case 2: If, however, we place antimatter atoms next to atoms of normal matter, they destroy each other and release a large amount of energy in the annihilation process.^2–4 Zafar et al. reported utilizing a tool called a positronium trap, which is capable of trapping positrons and electrons together in a bonded state known as positronium to produce electric current using positrons.⁵ 

Devices can be powered by positronium when a current flows through it. However, there are significant challenges to overcome before this technology can be used on a large scale. One of the biggest challenges is the short lifetime of positronium, which means that it is difficult to keep it stable for long periods. In addition, the cost of producing positrons is currently prohibitive. As a result, although the concept of producing electric current using positrons is significant, it is still in the experimental stage, and it might take some time before it becomes a practical energy source in the field of semiconductor devices. In an entirely laser-driven setup, Sarri et al. experimentally demonstrated that collimated, high-density ultra-relativistic positron beams are feasible,⁶ thus utilizing the electromagnetic cascade that begins when an ultra-relativistic electron source passes through a high-atomic number (Z) material. This is the most practical technique to produce positrons. Positron transport as a substitute source in semiconductor devices, with the expectation of boosting the output optical power and the radiative recombination, is one of the carrier-gun types shown in this Perspective’s roadmap for carrier transport technologies. It is critical to note that the author does not attempt to produce an exhaustive review of all work on e⁻ gun. It should be noted that the topic in this Perspective is limited to carrier sources, which include four different types of injector devices for photons, electrons, positrons, and Weyl fermions, which are quasiparticles. Meanwhile, the quasiparticle concept is important in condensed matter physics. The theory of quasiparticles was started by Landau in the 1930s.^7,8 Here, the report idea is harnessing e⁺ (type I) and Weyl fermions (type II) originated from the author’s concept of attempting to describe the charges with other properties as a beam/current for semiconductor pump/injection devices, invented for advancing semiconductors. The demand of this research is that the carrier can penetrate without any distractions by defects that are related to the Weyl fermion, thus developing fast optoelectronic and microelectronic components made from semiconductor heterostructures by using the introduced different types of carriers.

Since semiconductor lasers at this wavelength are limited, there has been an interest in UV and deep-UV light emitting and laser diodes based on the III-nitride material system and the wide bandgap (WBG) semiconductor. The achievement of creating laser diodes is restricted; nearly all accounts rely on optically stimulating the semiconductor using a more intense UV excimer laser, which is evidently an impractical approach. In addition, low output power and low efficiency are reported in all cases of electrically pumped LEDs and LDs, particularly as the wavelengths get closer to the ultraviolet. All existing sources are pumped either electrically or optically. In Ref. 9, the deficiency of appropriate shallow donor and acceptor dopants is addressed for photoconductive semiconductor laser diodes and LEDs that are electrically pumped. The conductivity of these layers can be efficiently increased by using subband gap light with enough energy to excite electrons (holes) from the comparatively deep donor (acceptor) levels in the n-type (p-type) layer. In Ref. 10, a semiconductor pump ultraviolet laser for the high conversion efficiency is specifically intended to the relevant type of laser of the present invention, which is a semiconductor pump ultraviolet laser with a high repetition frequency and a narrow pulse width that produces good beam quality. The pump light that is released from the pump coupling and focusing systems enters a double-end-face pump resonant cavity in the resonant cavity and is directed toward a laser working crystal. This invention presents a way to implement e⁺ and Weyl fermions as a beam/current for pump/injection semiconductor devices, which introduces a new concept of carrier generators for optoelectronic pump and injection devices. This approach addresses the primary limitation of optically and electrically pumped lasers based on AlN, AlGaN, or AlInGaN. The goal of this study is to use a particle other than the electron to enhance current injection.

The current research on describing e⁺ and Weyl fermions as a beam/current for semiconductor devices has extensively explored the replacement of conventional pump/injection sources, employing methodologies such as laser-driven high-quality positrons for semiconductor-based devices. However, since a significant gap remains in addressing less energy to produce a UV/DUV photon, a method is proposed for carrier injection, which reduces the impact of defects that might serve as carrier scattering sites, nonradiative recombination sites, or current leakage channels. There is a lack of empirical data on utilizing the proposed carriers in the semiconductor field. The studies of e⁺ source (positive carrier) have predominantly focused on positron annihilation spectroscopy as a means of characterizing defects in semiconductors,¹¹ leaving a gap to other implementation possibility of positive current injection. Thus, positron pumped optoelectronics research on light emitters either by standard electron beams or by positive positron beams. Future research should focus on transforming other charge carrier types such as positive positron beams and Weyl fermions to carry electric charge via a device far more quickly than ordinary electrons, therefore unlocking the potential of new materials with unusual transport properties.

Therefore, identifying and addressing these research gaps will significantly contribute to the field of semiconductors, paving the way for more informed and impactful research of using e⁺ and Weyl fermions as a beam/current for pump/injection semiconductor devices toward addressing the less energy production of a UV/DUV photon and the main drawback of the low absorption coefficient of the dopants. However, the realization of carrier injection into laser diodes and light emitting diodes (LEDs) with a high performance is promising as using conventional emitters is challenging because p-doping and ohmic contact formation are difficult to achieve and inefficient.^12,13 Another method that avoids the requirement of p-doping and superior ohmic connections is beam pumping of electrons or other proposed carriers. The proposed techniques are to inject a beam into the semiconductor system, where the boundary values of type I and II beams injected into the semiconductor materials should be the same as those of electrons to avoid any damage to the materials as a result of high beam interaction. However, this process requires selected values of beams that will lead to the dominance of radiative recombination from type I and II pumped beams, for realizing beam-injection laser diodes and high-performance light emitting diodes (LEDs).

This paper is organized as follows: Sec. II introduces e⁻ guns technology and design features of electron sources. Section III illustrates a new concept of alternative carrier transport sources and production techniques for the reasons of (I) including early pioneers in an effort to form an understanding of the invention of positron source and (II) expanding the aspects toward the implementation of alternative carrier transport sources for transport processes in optoelectronic devices. This section investigates how a charge moves through a solid and explains how a charge causes a quasiparticle to form inside the solid. In Sec. IV, the development history of electron beam-pumped emitters is examined along with the chosen device-processing technologies, demonstrating the need for further research into other carrier transport sources. The most important part of this research is Sec. V, where the positron or the antielectron process theory is proposed, leading to direct conversion into light. Section VIII provides a conclusion and a prospective direction. As the first to address the possible significance of other corpuscle types of current injection semiconductor devices, the author goes into detail about the concept of the beyond-laser future and possible innovation opportunities.

Electrons can be emitted from a filament, which is a cathode, by obtaining energy from heat or an electric field. The electron gun structure and its components are presented in Fig. 1. The four primary types of electron guns used in the current technology are as follows: thermionic, cold field emission, Schottky, and plasma cathodes. This raises the question of the future types of positron source, as shown in Fig. 2 for electron gun sources.¹⁴ 

One application of electron emitters is represented in Ref. 15. The generation of UV light using the electron beam pumping of quantum wells is efficient, and the current advancements represent a step toward a next-generation, small, high-efficiency UV light source. It should be noted that the electron beam is operating under conditions reported at ∼8 kV and 50 mA using the field-emission devices. The e⁻ beam attributes are compared to the characteristics of a surface that has been subjected to a 20–30 keV e⁻ beam.¹⁶ However, the assessment of a certain electron beam delivery is to be within the standard limit in eV values to avoid damage to the heterostructures’ properties. Type I semiconductor devices, which are the only electrical pumping sources, continue to be an obstacle to overcome. Although efficient p-type doping of wide-bandgap semiconductor materials such as SiC, GaN, AlN, InN, and Ga₂O₃ is difficult, doping with n-type is easier. Acceptors with a high activation energy result in a lack of holes, which significantly restricts the functionality and real-world use of wide-bandgap semiconductor devices. Meanwhile, the n-type dopant that is convincing is lacking; hence, a diamond device in which holes are the sole viable charge carrier is necessary.¹⁷ By implementing the other current types as a source of current, the possibility is to significantly resolve the doping issues. The improved performance is enhanced by increasing the carrier density and investigating the operation beyond the various current types’ limits. Pioneer work has been introduced to present the levels of peak ultraviolet-C (UVC) output powers achieved from heterostructures in the (Al,Ga)N system results demonstrated in the work of Tabataba-Vakili et al.,¹⁸ in which MQWs of a 10 × {Al_0.56Ga_0.44N/Al_0.9Ga_0.1N} heterostructure emitted a maximum peak power of >0.2 W at a wavelength of 246 nm when pulsed with an electron beam with an energy of 12 keV and a current of 4.4 mA. Moreover, UVC emitters based on heterostructures with multiple QWs of 400 × {GaN_1.5/AlN₁₆} grown using PAMBE on AlN/c-Al₂O₃ templates demonstrated a linear change in the output peak powers of UVC radiation up to 50 (10) W at a wavelength of 267 (238) nm, respectively, when pumped by an electron beam of 2 A generated by a pulsed electron gun with a plasma ferroelectric cathode.¹⁹ 

The principal practical applications of semiconductor carrier injection do not use positron sources. Neither positron sources nor any other sources such as Weyl fermions are used in the main practical applications of semiconductor carrier injection, according to a brief examination of the literature. It takes a lot of energy to keep the flow of electrons going since they are constantly clashing with other particles in the material or with each other, and a contribution with e⁺ flow could overcome this issue. Meanwhile, Weyl fermions experience almost no resistance as they pass through the material almost undisturbed. The electron-like antiparticle (e⁺) and Weyl fermions are considered potential for injectors, as shown in Fig. 3 for type I: radioactive source.²⁰ For type II: massless particles (Weyl fermions), more power is possible because it makes the flow of electricity almost free. Its effectiveness is addressed in Sec. V. For the positron beam production, a β+ emitting sodium-22 source, the positrons from this decay are highly energetic (∼300 keV) with the possibility of a slowed beam. Van House et al. reported e⁺ as the imaging particle and looked at how a positron beam with an energy of ∼2 eV interacted with a solid’s near-surface region.²⁰ During this process, the source e⁺, which was initially of high energy (∼100–500 keV), thermalized in a crystal, like a W crystal, and was ejected at an energy of ∼2 eV with a probability of 10⁻³–10⁻⁴. A beam is subsequently produced from the expelled e⁺. The existence of the positron, the electron’s antimatter counterpart, has sparked several examinations into its behavior, especially in this new area of study on the nature of its interactions and injections into semiconductor systems. For a new generation of semiconductor devices driven by energetic sources, the primary advantage is the substitution of the electron emitter with a positron beam source.

Generally, positronium consists of an electron and a positron, and a meson is made up of a quark and an antiquark. The positron is similar to the electron in terms of mass and spin, but the sign of its charge is opposite, although being the same in magnitude. In order to pump and inject semiconductor-based emitters based on a (Al,Ga)N material system, positron sources with wide energy distributions up to high energies (keV–MeV)⁵ have been proposed. However, the assessment of a certain electron beam delivery is to be within the standard limit in eV values, therefore avoiding any damage that leads to the influence of e⁻/e⁺ beam irradiation on electrical or optical characteristics. Many investigations into the behavior of positrons as well as their creation and use have been encouraged by the accessibility of the electron’s antimatter counterpart.

The techniques used to generate and harness the positron beam emission play a key part in explaining the behavior of the positron: (a) slow/fast positron beam technique and (b) laser-based source for electron and positron generation. Some materials are employed as “slow positron moderators,” such as thin single-crystal tungsten W(100) and nickel Ni(l00) foils. The radioactive sources that produce rapid positrons have mean energies in the range of several hundred kiloelectron volts.⁵ The energy of the positron beam is the same as that of the electron beam. For the positron beam production, a β⁺ emitting sodium-22 source is used as the starting point. Since the positrons produced by this decay have a high energy (300 keV), they must first be slowed down in order to be controlled for use in other studies.

Similar to electron and positron interactions, interactions of positronium with matter can reveal information about fundamental processes. In Table I, the summary of the development in the physics of the electron-like antiparticle—the positron—is shown. However, the first findings were made by imaging the particle positron in a transmission microscope.¹⁶ An e⁺ emitting radioactive source’s brightness, which is originally too low for imaging, is greatly boosted by a procedure known as moderation, which contributes to the instrument’s success.^21,22

The developing semiconductor heterojunction is based on positron carrier flow generated from a light source converting into positrons or with the possibility of converting the electron into a positron.⁴⁸ By employing a particle other than an electron as a probe of the target under investigation, the current positron generator can improve the current transport. The current positron generator can enhance the current transport by using carriers other than electrons to probe the devices being studied. Attention should be paid to the discovery of the characteristic positron radiation of the elements toward pioneering contributions to implementing the flow of positron carriers into semiconductors. The primary objective of Sec. III A 1 is to explore how the development of various carrier gun sources can be used to provide extreme particle beam delivery conditions that were previously unachievable. Consequently, this section looks at how the best laboratory device based on e⁺ emitters could be achieved.

The positrons that are emitted in the first stage pass through a layer of solid neon (T = 8 K) that acts as a moderator to slow down the positrons. A small percentage (less than 1%) of the positrons escape the moderator volume with a substantially lower kinetic energy (E = 50 eV), while the majority annihilate there. These lower energy positrons are then magnetically guided into the trap of the positron accumulator.^15,49–52

Positrons are an advantageous non-destructive probe type, but producing positrons from radioactive isotopes requires strict supervision. Conversely, laser-induced positron generation offers a controlled, non-radioactive source of positrons in the laboratory setting. Positron sources are driven by lasers as prospective injectors for plasma-based accelerators.⁵³ Positrons have the ability to distinguish between various types of atoms in addition to being able to detect defects in atomic structures. The positron electron annihilation produces a varied gamma spectrum depending on the element. Gamma radiation is detected and used as a fingerprint to identify the particular element.⁵⁴ Based on interactions between laser and plasma, there are three primary processes that can generate positrons: (I) trident, (II) Bethe–Heitler (BH), and (III) Breit–Wheeler (BW). Modern laser facilities have been used in experiments that successfully showed how to use the BH or trident process to produce the positron beam.^6,54–62

There are primarily two efficient techniques to generate positrons. First, a 1-step technique of the procedure directly irradiates a high-Z planar target using kilojoule class lasers operating at picoseconds (ps), which have a yield of up to 10¹² positrons.^56–58 Second, a 2-step technique indirectly generates positrons using femtosecond (fs) lasers:^6,54,59–62 this technique includes (i) quasi-monoenergetic electron production via laser wakefield acceleration (LWFA) and (ii) injection of the electrons into a high-Z target to produce positrons. In the 2-step technique based on LWFA, the positron beam offers noteworthy advantages such as high energy (several hundred megaelectron volts), limited divergence (a few MRAD), and short duration (fs scale).^6,59–61

However, Wang et al. proposed a new technique for producing high yield positrons by combining a femtosecond (fs) laser contact with a micro-structured surface based on a multi-layer type MST, a high-Z converter, and a femtosecond laser interaction.⁷¹ A high-Z converter with a femtosecond laser pulse is used to produce positrons on the micro-structured surface target (MST), as shown in Fig. 4. Stages No. 1 and 2:^71,72 in stage 1, femtosecond laser radiation is applied to a multi-layer type MST. From the target’s back side, energetic electrons are created and released. In stage 2, via the BH process, these high-energy electrons enter a high-Z converter and produce positrons. Moreover, in this Perspective, the incorporating of stage 3 is proposed for collecting the positron beam toward semiconductor injection. The MST is a solid planar target with fabricated fine structures, such as layers,⁶³ wires,^64–69 and slots⁷⁰ or holes,⁷³ on its surface. By changing the surface from “surface heating” to “volume heating,” which increases laser absorption and electron heating, the interaction between the laser and the target can be altered.⁶⁶ 

• In stage 1, the MST is irradiated using a femtosecond laser. At this point, positron production can be ignored because copper is a mid-Z material.

• It is shown that a laser of 36 fs duration, 7 µm spot size, 10²⁰ W/cm² intensity, and 6 J energy will produce 10⁹ positrons.

Nevertheless, since solid targets have more electrons than gas targets do, the laser–solid interaction can deliver more electrons, resulting in more positrons.⁷¹ According to Liang et al., bombarded solid gold and platinum targets with pulses of 100 joules and a pulse width of 130 fs, the maximum positron yield few 10¹⁰ was recorded using fs lasers. At energy of several tens of megaelectron volts, positron generation reaches its maximum.⁷⁴ Maximum positron production occurs at energies of many tens of megaelectron volts.

The study of the space distribution of photo-electrons emitted from various gases by x rays is one of the most significant of the century, so what about photon–positron emission or other charges rather than electrons? Since Dirac published his formula outlining the precise characteristics of the electron, he discovered that there were both positive and negative solutions to the equation. In other words, this implied the possibility of an electron-like particle with the opposite charge. This caused significant concerns regarding Dirac’s equation up until Dr. Anderson at Caltech found positrons among the particles produced in a cloud chamber by cosmic rays.

When a straightforward solution to a persistent issue is discovered, it frequently has a significant scientific or technological influence. The majority of scholars think that this issue is the most challenging obstacle in this field. The evaluation and delivery of certain electron beam semiconductor devices is to be within the standard limit in keV values, avoiding any damage that leads to the influence of electron-beam irradiation on electrical or optical characteristics. Semiconductor devices that are solely electrically pumped by electrons remain a challenge. SiC, GaN, AlN, Ga₂O₃, and other wide-bandgap semiconductor materials are easily doped n-type; nevertheless, efficient p-type doping of these materials is quite challenging. Acceptors of high activation energy result in a lack of holes, which significantly restricts the functionality and real-world use of wide-bandgap semiconductor devices. Meanwhile, the n-type dopant that is convincing is lacking; hence, a diamond device in which holes are the sole viable charge carrier is necessary.¹⁷ 

By implementing the other current types as a source of current, the possibility to significantly resolve the doping issues and enhance the improved performance is attained by increasing the carrier density and investigating the operation beyond the various current types’ limits. Thus, it is interesting to design alternative UV emitters based on p-type AlN/GaN, where emission is generated by pumping with an e⁺ beam. A single photon has the ability to produce a shower of high-energy particles at very high energies. The innovative work in developing techniques for polarizing beams of positrons has been addressed.^23,24

In the microscope-based positrons, a pulsed beam of positrons is pumped into the sample. Positron influx into the material is rejected by atomic nuclei and drawn to electrons. Numerous positrons diffuse into voids when nuclei are absent due to the repulsion of nuclei. Every positron will come into contact with an electron and be annihilated, typically within a few hundred picoseconds (10⁻¹² s).⁷⁷ The gamma ray is converted to electric power by ejecting a pulse of positrons and the gamma rays that are produced as a result of positron–electron annihilations. Because of the impact that gamma-ray irradiation has on the forward I–V curve of GaN-based blue LEDs both before and after irradiation, Hongxia et al. have already reported on this method to InGaN/GaN LEDs.⁷⁸ It was demonstrated that for samples with and without γ-ray radiation, the I–V characteristic is equivalent to 2.82 V at low doses (30 kGy). Therefore, controlling the number of doses reaching the semiconductor epitaxial layers is critical. Together with the light output power and photoelectric conversion efficiency, the luminous flux Φ exists and varies with the different radiation dose values.

This is an important indication that pumping with positive electrons with controlling the gamma rays in correlation to the e⁺ flow values that are produced as a result of positron–electron annihilations after a pulse of positrons or injected positrons will lead to current flow and a change in the electronic structure of the materials to be conducive.

Unlike electrons, Weyl fermions are massless and behave as both matter and antimatter inside a crystal and possess a high degree of mobility.⁷⁹ Weyl fermions, which were first predicted in 1929, have special qualities as well that could contribute to the development of quantum computers and high-speed electrical circuits.⁸⁰ Weyl, a German mathematician, discovered another solution to the Dirac equation, but this time, it concerned massless particles. Due to their fundamental characteristics, Weyl fermions move rapidly on the crystal’s surface without backscattering, which reduces the efficiency and increases the heat rate in typical electronic materials. Weyl points may also be realized in photonic crystals, according to a 2013 publication, as condensed-matter physics incorporates Weyl physics.⁸¹ Weyl quasiparticles are partially protected from scattering since they have non-trivial topological features and obey relativistic equations of motion. Because Weyl fermions are massless, they can carry electric charge through a material far more quickly than regular electrons. This property might be used to build optoelectronic devices that operate more quickly.^47,82,83

Weyl electrons are understood to transfer electric current at least twice as quickly as graphene electrons and at least 1000 times faster than electrons in ordinary semiconductors, according to the most recent studies.⁸³ In an effort to further this field of study, this study is harnessing Weyl electrons as beam/current in pump/injection semiconductor devices.

A positron is considered an energy source of unique non-destructive technique with the conservation of energy. The positron beam has an energy of 10 MeV, which is similar to the electron beam, and when done without the use of radioactive material, this provides 1000 times more energy than nuclear fission of the same mass.⁸⁴ In the case of e⁺ injection into the semiconductor, the characteristic γ-ray released in the annihilation and release of photons should be within a specific range to act as a carrier source. Mass is transformed into energy during the annihilation of the positron and electron, which releases photons. A 10 MeV positron beam was obtained, and an optical maser was used to increase the current intensity to 10²⁰ e⁺/s.⁸⁴ Positrons are important because they have the highest energy density of any particle, up to 10¹⁷ J/kg, which has inspired the creation of compact optical masers.⁸⁵ 

An innovative type of carrier source based on positronic transport and Weyl fermions is given special consideration. In this Perspective, the aim is to build on the concept of “positron injection” for positron beam pumped semiconductor-based devices of type I: positron source and type II: Weyl fermions for their high mobility and topological protection. This Perspective describes how a beam of antimatter particles is used to examine defects in a semiconductor as well as used for pump/injection semiconductor devices. Demonstrating the capabilities of this type of beam generator and its use in novel applications, carrier sources created in the lab that operate in the CW and pulsed modes will excite the (Al,Ga)N system. Pairs of electrons and positrons (antimatter electrons) are created using enough accelerated particles or gamma rays. While most heterostructure semiconductor components were injected with a single charge type, such as electrons, the foundation for modern semiconductors is based on multiple charge types, resulting in superior transport qualities across the active layer. The advantage is the fast radiative lifetime associated with positron charge properties. The aim of the present project is to develop a positron microbeam as the first attempt to describe e⁺ as beam/current for pump/injection semiconductor devices. Therefore, the first attempt to describe e⁺ and Weyl fermions as a beam/current for pump/injection semiconductor devices and harness other charged carriers rather than electrons originating from Arwa’s concept addresses the potential for the electron’s charge state to flip into e⁺. These proposed beam sources (e⁺ and Weyl fermions) are used to enhance electronic and optoelectronic devices by implementing them in the semiconductor industry.

The author has no conflicts to disclose.

The author read and approved the final manuscript.

Arwa Saud Abbas: Conceptualization (equal); Data curation (equal); Formal analysis (equal); Funding acquisition (equal); Investigation (equal); Methodology (equal); Project administration (equal); Resources (equal); Software (equal); Supervision (equal); Validation (equal); Visualization (equal); Writing – original draft (equal); Writing – review & editing (equal).

All data and figures presented in this article are based on the materials available through the corresponding references with their permission.