DOMINANT DEEP-LEVEL IN ANNEALED LOW-TEMPERATURE GAAS-LAYERS GROWN BY MOLECULAR-BEAM EPITAXY

Deep levels in the annealed low temperature molecular beam epitaxial(LT-MBE) GaAs layer were characterized by using the capacitance-deep-level transient spectroscopy (DLTS) technique in combination with a unique sample structure. We have fabricated the samples by inserting the LT-GaAs layer between two n-type semiconductive layers grown at normal substrate temperatures, like a sandwich. DLTS measurements revealed that one electron trap dominates the annealed LT-MBE GaAs layer. This dominant electron trap was very similar to the so-called EL3 level. By changing growth parameters of LT-Gabs layers, we found that the trap concentration of this EL3-like level was strongly related to Si doping and excess arsenic.