Investigation of the low-temperature CL contrasts of dislocations in compound semiconductors

Abstract

Quantitative cathodoluminescence (CL) defect contrast studies were performed at single grown-in and isolated glide dislocations in (001) GaP, (001) GaAs and (111) CdTe samples for temperatures T = 300−5 K. Dark and bright CL defect contrasts observed in the low temperature range exhibit thermally activated behavior or show thermal quenching. Analyzing the contrast temperature dependence taking into account temperature-dependent matrix parameters allows to evidence temperature-induced changes of the recombination activity of the dislocations concerned. The results obtained for the misfit defects in GaP and As(g) dislocations in GaAs proved in both cases non-radiative thermally activated defect-bound recombination rates. The bright CL contrasts correlated with the Te(g) line segments of glide dislocations in CdTe point out defect-bound radiative recombination. Its photon energy peak is at 1.48 eV (5 K), the emission intensity is quenched above T ≥ 120 K, from what a defect-bound excitonic process might be concluded. Despite the distinct contrast behaviors a qualitatively similar rise of the defect recombination strength with increasing temperature is deduced for the structurally different dislocations studied.