Minority-carrier lifetime measurements of efficient GaAlAs p-n heterojunctions

High-efficiency Ga1−xAlxAs p-n heterojunctions have been fabricated by the temperature-difference method (ηRT, 1–3% at 6650 A), and the deep levels which govern the efficiency and the lifetime have been studied by I-V, C-V, photocapacitance, impedance, and electroluminescence measurements. The lifetime obtained by the impedance measurement and the deep-level distribution obtained by the C-V measurement have a correlation. The lifetime for efficient diodes is as low as 1 μs at 80 K. The temperature dependence of the lifetime was also measured. Photocapacitance spectra show a threshold photon energy of 0.65 eV. Arsenic vacancies are proposed for these deep levels.