DEEP LEVELS IN UNIFORMLY SI DOPED GAAS ALXGA1-XAS QUANTUM-WELLS AND SUPERLATTICES/

Uniformly Si doped GaAs/Al0.33Ga0.67As multilayer structures have been studied by deep level transient spectroscopy (DLTS) and photocapacita nce measurements. DLTS spectra showed five peaks which are related to defects in the GaAs layers. The concentration of these defects decreas ed with increasing layer thickness. An additional peak, which has been observed with forward bias filling pulses, is suggested to be related to defects near the surface, most probably due to defect accumulation in multilayers. Their emission and capture properties as well as phot oionization cross sections have been studied. Evidence is provided tha t the emission and filling processes of these deep levels are modified due to the energy quantization in the conduction band and the carrier transport through the quantum structures. No DX center related DLTS p eaks or other features like persistent photoconductivity effects have been observed in any of our samples. (C) 1996 American Institute of Ph ysics.