Transient Behavior of Transverse Acousto electric Voltage and Nondestructive Characterization of Semiconductor Surfaces

Abstract

Nondestructive characterization of semiconductor surfaces and interfaces by the surface-acoustic-wave (SAW) technique is demonstrated and reviewed. The sensitivity and applicability of this method is greatly improved by the introduction of a new delay-line structure and the further theoretical development of the SAW-semiconductor interaction. The monitored signal in the following work is the transverse acoustolectric voltage (TAY). A detailed theoretical discussion of the TAV transient behavior is presented, which has not been treated previously. The theoretical development leads to the approximate relationship between the TAIT transient time constant and the carriers generation lifetime (re) and surface generation velocity (Se). The new delay line structure has enabled us to vary the surface potential via a small external bias field (about 100 times smaller than the previous work and comparable to the capacitance-voltage voltage range). The TAV amplitude and transient time constant can be measured while the bias field is applied across the semiconductor. Parameters such as rgSgwhich are indications of the bulk defect density and surface condition, are monitored to evaluate such processes as gettering, chemical etching, polishing, and annealing. © 1985 IEEE