FIG. 3.15 Band diagrams of (a) valence band and (b) conduction band in the GaN/InGaN p–i–n structure. Carrier wavefunctions are not centrosymmetric due to polarization. E p and E n are the first bound states in the valence and conduction bands, respectively. (c) Induced sheet charge at the interfaces of QW due to polarization. More about this image found in Band diagrams of (a) valence band and (b) conduction band in the GaN/InGaN ...

FIG. 3.20 Band diagrams of the AlGaN/GaN heterostructure for HEMT. Strained AlGaN is grown pseudomorphically on relaxed GaN. A positive polarization charge ( + σ ) is induced at the interface, which attracts electrons and forms 2DEG. More about this image found in Band diagrams of the AlGaN/GaN heterostructure for HEMT. Strained AlGaN is ...

FIG. 3.18 Schematic of typical Ga-faced HEMT device structure. A nucleation layer is grown on the substrate for accommodating lattice mismatch. 2DEG is formed at the interface of the AlGaN/GaN interface on the GaN side. Thin GaN is formed at the top to make better contact. More about this image found in Schematic of typical Ga-faced HEMT device structure. A nucleation layer is ...

FIG. 3.19 Illustration for spontaneous and piezoelectric polarization-induced sheet charge at the AlGaN/GaN interface for Ga-faced and N-faced growth direction. More about this image found in Illustration for spontaneous and piezoelectric polarization-induced sheet c...

FIG. 13.2 State-of-the-art SiC, GaN and Ga₂O₃ Schottky Barrier Diode (SBD) performance. Specific on-resistance R_on,sp and V_f normalized to area are plotted for each semiconductor. The dashed lines represent the R_on,sp vs breakdown voltage theoretical limit for each material ( Bhatnagar et al., 1992 ; Takatsuka et al., 2018 ; Lin et al., 2019 ; Lynch et al., 2019 ; Xiao et al., 2020 , 2021 ; Roy et al., 2021 ; Dong et al., 2022 ; Kumar et al., 2022 ; and Zhang et al., 2022 ). More about this image found in State-of-the-art SiC, GaN and Ga₂O₃ Schottky Barrier ...

FIG. 3.5 Sketch of the two-layered microcantilever made of an elastic substrate and coated ultrathin film performing (a) flexural and (b) torsional oscillations. Reprinted with permission from Stachiv and Gan, Coatings 9 (8), 486 (2019). Copyright 2019 MDPI. More about this image found in Sketch of the two-layered microcantilever made of an elastic substrate and ...

FIG. 3.14 Structure of typical III-nitride LEDs. Device operation depends on the lateral current injection. The buffer layer is grown on a substrate at low temperatures to accommodate high lattice mismatch. (a) InGaN MQW-based LEDs for blue/green/yellow LEDs. AlGaN-based electron blocking layer is used to prevent injected electrons from escaping the active region. (b) AlGaN MQW-based UV LEDs. p-GaN is grown on p-AlGaN to prevent oxidation of aluminum. More about this image found in Structure of typical III-nitride LEDs. Device operation depends on the late...

FIG. 13.8 R_ON × Q_G vs V_BK comparison of GaN SOA ( Wong et al., 2017a ), GaN COTS ( EPC, 2021 and Transphorm Inc., 2022 ), BGO switch ( Chabak et al., 2020 and Dryden et al., 2022 ) and estimated BGO devices. More about this image found in R_ON × Q...

FIG. 8.4 (a) Schematic of a self-leveling capacitive VOC sensor. (b) SEM image of the self-leveling sensor (i) 450 µm long device with PDMS polymer and (ii) magnified image of the suspended top electrode of the device with etch holes (i) Reproduced with permission from Likhite et al., Sens. Actuators B Chem. 311 , 127817 (2020). Copyright 2020 Elsevier. (c) SEM images of AlGaN/GaN heterostructure based dual channel MC heater design [(i) and (ii)] SEM images of a monolithic tip dual channel MC heater. The sensor and heater channels are visible in (ii). (iii) and (iv) Split tip dual channel MC heater with sensor and heater channels marked in (iv). Reproduced with permission from Jahangir and Koley, Sci. Rep. 6 , 28735 (2016). Copyright 2020 Author(s), licensed under a Creative Commons Attribution 3.0 Unported License. (d) Graphene membrane resonators (i) angled SEM image of suspended graphene membranes over fabricated trenches in SiO₂. (ii) Angled SEM of an array of graphene membranes. (iii) Optical image of a large array of graphene membranes. Reprinted with permission from van der Zande et al., Nano Lett. 10 (12), 4869–4873 ( 2010 ). Copyright 2010 American Chemical Society. More about this image found in (a) Schematic of a self-leveling capacitive VOC sensor. (b) SEM image of th...

FIG. 1.7 Deep levels in Al_xGa_1-xN as a function of Al composition showing shallow to deep level transition of donor levels as the material transforms from WBG GaN to UWBG Al_xGa_1-xN ( Kamyczek et al., 2012 ). More about this image found in Deep levels in Al_xGa_1-xN as a function of Al composit...

FIG. 1.22 Experimentally obtained maximum operating temperature vs maximum reverse breakdown voltage of Schottky diodes showing β-Ga₂O₃ devices can reach high-temperature and high-breakdown operation with simpler designs compared to SiC and GaN ( Wang et al., 2019 ). More about this image found in Experimentally obtained maximum operating temperature vs maximum reverse br...