Effect of the 0.94, 1.0, 1.2, and 1.3 ev radiative centres on the intrinsic luminescence intensity in n-GaAs

The relative role of radiative and non-radiative recombination centres in the decrease of the intrinsic luminescence intensity Icv in n-type GaAs crystals at different doping levels (n0 = 5 × × 1016 to 6 × 1018 cm−3), excitations (L = 1018 to 3 × 1020 quanta/cm2 s), and temperatures (T = 77 to 600 K) is studied. It is shown that both the radiative r-centres (the electron recombination via these centres gives rise to the emission bands at hvm(77 K) = 0.94, 1.0, 1.2, and 1.3eV) as well as non-radiative s-centres could play an essential role in the decrease of Icv. The low quantum efficiency of intrinsic emission η of moderately doped n-type GaAs crystals (2 × 1017 cm−3 ≦ ≦ n0 ≦ 3 ≦ 1018 cm−3) at low temperatures and low excitation intensities is caused by r-centres. The low quantum efficiency of intrinsic emission of lightly (n0 < 2 × 1017 cm−3) and heavily (n0 < 3 × 1018 cm−3) doped n-type GaAs crystals at all temperatures and excitation intensities and moderately doped n-type GaAs crystals at high temperatures or at high excitation intensities is caused by s-centres.