Capacitance dispersion in n-LT-i-p GaAs structures with the low-temperature layers grown at different temperatures

Abstract

The electrical properties of annealed low-temperature GaAs are studied by investigating the frequency-dependent capacitance of n-LT-i-p structures with the low-temperature (LT) layers grown at different temperatures. Relative to the sample grown at 610 degrees C, the samples grown at 200, 300 and 400 degrees C show significant capacitance dispersions over frequency which is explained by the emission of carriers from traps. Based on a proposed band diagram where a dominating trap at 0.66-0.74 eV exists in the LT layers, the high-frequency dispersion is shown to be affected by resistance-capacitance (RC) time constant effects. From the mid-frequency capacitance versus voltage characteristics, the concentrations of the occupied traps are estimated to be approximate to 10(17) cm(-3) for samples grown at 200, 300 and 400 degrees C, which are found to be consistent with those obtained from analyzing the current-voltage characteristics of n(+)-LT-n(+) structures.