The magnetic field dependence of R₀A products in n-on-p homojunctions and p-on-n heterojunctions from Hg_0.78Cd_0.22Te liquid phase epitaxy films

Abstract

The analysis of R₀A products as a function of magnetic field in n-on-p diodes using a simple diffusion current model has previously been shown to yield both J_ep/J_total ratio (the relative contribution of the p-side diffusion current) and μ_ep (the minority carrier, electron mobility). In this paper, we report the good agreement between the experimental and theoretical dependence of μ_ep on the hole concentration over a wide range between 1 x 10¹⁶ and 4 x 10¹⁷ cm⁻³ in n-on-p homojunction diodes fabricated on undoped p-type Hg_0.78Cd_0.22Te liquid phase epitaxial (LPE) films. The averaged J_ep/J_total ratio varied between 68 and 90% with the hole concentration. These J_ep/J_total ratios indicate that other leakage current mechanisms than the p-side diffusion current were not negligible. Also, for the first time, comparative measurements were made on p⁺/n heterojunction diodes consisting of As-doped Hg_0.07Cd_0.30Te and In-doped Hg_0.78Cd_0.22Te LPE layers. Unlike a typical change in R₀A products by a factor of 2–3 in n-on-p homojunction diodes, the R₀A products in p⁺/n heterojunction diodes at 7 kG were typically only 2–3% higher than that at the zero field. The typical J_ep/J_total ratio in p⁺/n heterojunction diodes was about 3–4 %, which confirms the general belief that the p⁺ cap layer, due to the high doping and a larger bandgap, contributes very little to the total leakage current.