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)In_xAs 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) μm 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) μm and (6.2 ± 0.5) ns respectively for GaAs to (14 ± 2) μm and (24.4 ± 0.5) ns respectively for Ga_0.79In_0.21As. 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.