A new method to analyze closely spaced deep defect levels caused by multiexponential transients

Abstract

A new method is presented to analyze nonexponential capacitance transients, caused by closely-spaced deep defect levels active at the same temperature range, into the appropriate components. It is capable to resolve deep-level transient spectroscopy (DLTS) signals having one or more shoulders, generated by two or more trap levels. Closely-spaced traps are accompanied by the observation of multiple emission rates making the differentiation between them almost impossible using conventional analysis techniques. The proposed method utilizes a hybrid between the conventional DLTS technique, based on Lang's method [1], and the non-linear double exponential fitting routine previously published by the author. This technique was successfully tested on Se-doped n-type Al x Ga 1-x As sample, having what is known as DX centers, and was capable of resolving up to seven deep levels with activation energies ranging from 270 -486 meV.