Identification of the Nature of Deep Trap States in Molecular Beam Epitaxially Grown Gallium Arsenide

Abstract

In this article we present a complete overview of our investigation on deep trap states in molecular beam epitaxy (MBE)-grown Si-implanted, low temperature (LT)-GaAs and high-temperature (HT)-GaAs by field effect deep level transient spectroscopy (FEDLTS). The LT-GaAs and HT-GaAs samples were grown at 300 o C and 750 o C, respectively. FEDLTS studies were conducted on Schottky diodes fabricated on these samples using Au contacts in the temperature range 100−350 K. We have included the lambda-effect and lambda-delta effect in the determination of deep trap concentrations and capture cross sections. Our study indicates that the deep traps identified in LT-GaAs and HT-GaAs are all bulk deep traps (BDT). No near-surface-deep traps (NDT) were detected in either of these materials. Furthermore, the effective deep trap concentration, in both LT-GaAs and HT-GaAs, increased with temperature showing a two-step linear rise and ending with a tendency to saturate around 350 K. The ionization energy of the carriers indicated a linear relationship with temperature in the above temperature range from 0.05 eV to 0.30 eV for LT-GaAs and from 0.02 eV to 0.12 eV for HT-GaAs.