Minority carrier diffusion length, lifetime and mobility in p-type GaAs and GaInAs
Minority carrier diffusion lengths and lifetimes were determined for p-type Ga(1-x)InxAs with an In-content of 0 < x < 0.53 by cathodoluminescence and time-resolved photoluminescence measurements respectively under low injection conditions; the resulting minority carrier mobilities are also reported. Highly p-doped samples (3 × 1018 cm−3) demonstrate a constant minority carrier diffusion length of (5.0 ± 0.7) mm and a constant lifetime of (3.7 ± 0.7) ns for an In-content up to 21%. Lower doped samples (3 × 1017 cm−3), on the other hand, show an increase in minority carrier diffusion length and lifetime with In-content from (6.3 ± 0.2) mm and (6.2 ± 0.5) ns respectively for GaAs to (14 ± 2) mm and (24.4 ± 0.5) ns respectively for Ga0.79In0.21As. Increasing the In-content to 53% results in a drop in the minority carrier diffusion length independently of the p-doping concentration .This is interpreted as a change in the energy of the Shockley-Read-Hall trap levels within the bandgap as a function of indium concentration.