Investigation of the Recombination and Trapping Processes of Photoinjected Carriers in Semi-Insulating Cr-Doped GaAs Using PME and PC Methods

Abstract

Investigation of the recombination and trapping processes of photoinjected carriers in semi‐insulating Cr‐doped GaAs (ρ ∼ 10⁸ Ω cm) has been made at 80 and 300°K, using the photomagnetoelectric (PME) and photoconductive (PC) effects under large‐injection conditions. A generalized theory for the PME and PC effects is developed, taking into account the variation of carrier lifetimes with injected‐carrier density (i.e., τ_n = κΔn^β) and of the trapping of holes in the Cr levels (i.e., Δp = ΓΔn, ΓI_PME varies as ΔG²/^(2+β), valid for different injection ranges. Two well‐defined ranges of injection were observed from the present results: In region I (high injection), I_PME is directly proportional to ΔG (i.e., β = 0), and in region II (intermediate injection), I_PME varies with ΔG^1.2 (i.e., β = −⅓). Numerical values of τ_n, τ_p, and I_PME as functions of ΔG are given. The results are in good agreement with the theoretical predictions.