Resistivity analysis on n-semi-insulating-n and p-semi-insulating-p structures exemplified with semi-insulating InP

Abstract

Current–voltage characteristic in semi-insulating (SI) InP layers sandwiched between n- or p-type layers have been simulated. Deep acceptor and deep donor levels were considered. A one-dimensional two-carrier numerical model was used, which takes into account carrier diffusion and Shockley–Read–Hall recombination through the deep traps. The current–voltage behavior is studied in the linear ohmic regime in order to deduce the resistivity, which is analyzed and compared to values obtained from equilibrium calculations. The simulations predict an increased resistivity for n-SI-n and a decreased resistivity for p-SI-p structures, while increasing the concentration of deep acceptors. Furthermore, a maximum in the resistivity as a function of the trap concentration is found for an n-SI-n structure, which accommodates electron injection. In addition, the influence of the position of the deep acceptor in the band gap on the resistivity is analyzed, and it is shown that it significantly affects the behavior when comparing n-SI-n and p-SI-p structures. Incorporating a deep donor level along with a deep acceptor level will improve the SI behavior of the p-SI-p structure, whereas a slight drop in resistivity occurs for the n-SI-n structure. Our predicted electrical behavior from simulation is found to be in accordance with the previously published experimental results in InP:Fe and InP:Fe,Ti.