Hexagonal boron nitride (h-BN) is a versatile material due to its ultra-wide band gap and large neutron capture cross section. However, its properties are not commonly studied or well understood. In a recent paper, researchers report a measurement of charge carrier drift mobilities and lifetimes of both electrons and holes in h-BN.
While previous transport measurements of h-BN have only been able to measure the product of electron or hole drift mobilities and lifetimes, Grenadier et al. decoupled the quantities and measured them separately. Furthermore, the researchers made these measurements for both electrons and holes, though more traditional methods, such as Hall-effect measurements, can typically only study one or the other.
By combining a charge sensitive preamplifier and a shaping amplifier, the group was able to directly obtain the charge carrier lifetimes and the drift mobilities. They extracted the charge carrier lifetime from the correlation between the charge carrier transit time and the peak voltage of the system and found drift mobilities by fitting the charge carrier velocity as a function of electric field. Additionally, flipping the direction of the electric field applied to h-BN allowed them to study the mobilities of both electrons and holes.
The scientists note finding ways to enhance these properties is critical for improvements in h-BN technologies.
“The research presented in this paper gives us better understanding of some of the key fundamental electrical transport properties of h-BN,” said author Sam Grenadier. “This will have a direct impact on the fabrication of future h-BN based neutron detectors by minimizing the factors that impact charge trapping in this material.”
Source: “Lateral charge carrier transport properties of B-10 enriched hexagonal BN thick epilayers,” by S. Grenadier, A. Maity, J. Li, J. Y. Lin, and H. X. Jiang, Applied Physics Letters (2019). The article can be accessed at https://doi.org/10.1063/1.5097984.
