A new sequential four-rate-window DLTS system

A deep-level transient spectroscopy (DLTS) system is described that permits four simultaneous sequential DLTS spectra to be obtained during a single thermal scan. Using a commercial capacitance meter, a self-contained low-cost versatile unit has been designed that gives a signal-to-noise ratio better than 100 dB, baseline suppression, a resolution better than 0.5 fF, and a response time lower than 100 μs. The DLTS system uses a novel ramp generator to drive the sample temperature controller. This provides the facility to change the scan temperature range without loss of precision. The application of this system to measure the Au acceptor level in Si and Te-related traps (DX centers) in GaAlAs (x=0.65) is described.