Near-surface deep-trap and bulk deep-trap states in In_xGa_1-xAs/GaAs

Field-effect studies have been performed to investigate the near-surface deep-trap and bulk deep-trap states in molecular-beam epitaxy-grown In_xGa_1-xAs (where x=0.1) on n⁺ GaAs. We have measured the isothermal capacitance transients for the major trap levels in the range of 77–380 K in the reverse-bias field of -1 to -3.8 V/cm. The results of our investigation indicate a distinct effect on the deep level spectra due to the applied field, suggesting a definitive way to identify the near-surface deep traps from the bulk deep traps, and vice versa. The two major deep traps identified in the present investigation further display a transition from one state to another, from near-surface to bulk state in the high-field region, when the applied reverse-bias field is increased from -3.0 to -3.8 V/cm. “Field” means “normalized” field, F(norm)=F(appl)×10^-5. © 2002 American Vacuum Society.