Electrical characterization of semiconductor materials

摘要

A method for characterizing the electronic properties of a semiconductor sample by exploiting transients in measured photoconductance, the transients being induced by illuminating the semiconductor sample with a small probing illumination that is superimposed over a larger background illumination. In one embodiment, a pulse-type probing illumination is utilized, with either the intensity of the probing illumination being gradually reduced or the intensity of the background illumination being gradually increased until the measured photoconductance rise and decay in the sample are substantially exponential. In another embodiment, a continuous probing illumination with a sinusoidally-modulated intensity is utilized, the modulated intensity of the probing illumination being gradually adjusted until the measured photoconductance is linearly dependent thereupon.

主权项

1. A method for characterizing electronic properties of a semiconductor sample, the method comprising:
illuminating the surface of the semiconductor sample with a background illumination having a predefined intensity and photon energy higher than an energy gap of the semiconductor; taking a first photoconductance measurement of the semiconductor sample to verify the establishment of a first state of steady-state photoconductance; illuminating the surface of the semiconductor sample with a probing pulse of light of a particular intensity, the probing pulse of light being superimposed over the background illumination; taking a second photoconductance measurement of the semiconductor sample to verify the presence of a second state of steady-state photoconductance; measuring a photoconductance rise and decay in the semiconductor sample after the cessation of the probing pulse of light; and analyzing the photoconductance to determine if the photoconductance rise and decay are substantially exponential.