Dependence of the electron diffusion length in p-InGaAs layers on the acceptor diffusion process

The authors have investigated the influence of different acceptor diffusion methods on the diffusion length of the minority carriers (electrons) in InGaAs/InP samples. Zn and Cd were diffused into InGaAs separately or simultaneously. The diffusion length was estimated by fitting numerical calculations to the measured spectral response of pn structures with different junction depths. The results support the assumption of the creation of crystal defects during the diffusion, which enhance recombination processes and make the carrier lifetime small. Consequently, the diffusion length does not achieve the magnitude that should be possible theoretically. The values estimated were LD =0.4-0.6 mu m at p-doping levels of about 2-4*1019 cm-3. The experimental results show that the diffusion length does not depend significantly on the diffusing species.