Analysis of Thermally Stimulated Current Spectroscopy in Semiinsulating GaAs. I. Initialization

The operation of improved thermally stimulated current (TSC) spectroscopy is described and analysed. This method is suited for studying defects in semi-insulating (SI) GaAs at liquid-helium temperatures. This paper, the first in a series, presents an analysis of the first half process of TSC, that is, initialization, which consists of three stages: carrier generation, transport, and trapping. The initialization is analysed in terms of such parameters as electrode spacing, biasing voltage and polarity, excitation light energy and dose, and temperature. The analysis leads to new methods of determining the cross section of a deep level trap. From the photocurrent transient, the cross section was estimated for the dominant trap(s) as 5×10-15 cm2. Another method offers an estimation for nondominant trap levels.