Paired temperature spectroscopy: a novel method to characterise traps in semiconductors

Abstract

The authors present a novel technique, Paired Temperature Spectroscopy (PATS) to characterise traps in semiconductors. The technique is based on subtracting the capacitance transients at two temperatures, one of which may be the room temperature. The technique bears a resemblance to the deep-level transient spectroscopy (DLTS) of Lang, but differs from it in important respects: it does not require a thermal scan and a dual box-car or analogous signal-filtering mechanisms. The use of fixed temperatures also permits the use of signal averaging and an enhanced signal-to-noise ratio. They show that the technique is sensitive, rapid and lends itself to an easy analysis of trap depth and capture cross section related parameters. It also does not require that the transient be a simple exponential and hence can be used to determine the broadening of defect levels in ternary and quaternary alloys such as Ga_1-xAl_xAs and In_1-xGaxAs_1-yP_y. They demonstrate the utility of the technique by analysing both simulated transients and experimental data on GaAs_1-xSb_x.