Understanding the C-V Characteristics of InAsSb-based nBn Infrared Detectors with N and P-type Barrier Layers Through Numerical Modeling

Capacitance-voltage (C-V) profiling is a useful technique for accurate and non-destructive determination of carrier concentrations in semiconductor materials. Recently, this measurement has been applied to the infrared barrier detector to determine the doping densities of the absorber and contact layers. This paper provides three contributions to the development of barrier detectors. First, we develop a physics-based semi-analytical model for computing the C-V characteristics derived from metal-oxide-semiconductor and heterojunction device physics and show that it is in agreement with results obtained from drift-diffusion simulations. Second, we assess the possibility of using the developed model to determine not only the absorber and contact doping densities, but also the doping density and thickness of the barrier layer. Lastly, we use the same drift-diffusion methodology to conduct a comprehensive parametric study of the C-V profile for a variety of absorber n-type doping densities, barrier N- and P-type doping densities, barrier thicknesses, and contact layer n-type doping densities. We also offer an extensive discussion of the role of the various device parameters on shaping the C-V profile. While this paper uses the InAsSb and AlAsSb material system, the analysis can be extended to other materials used to implement barrier devices, such as HgCdTe or superlattices.