A DEEP-LEVEL TRANSIENT SPECTROSCOPY TECHNIQUE FOR THE CHARACTERIZATION OF CHARGE-CARRIER EMISSION CENTERS IN NONABRUPT P-N-JUNCTIONS

A measurement method has been developed which makes it possible to determine the thermal emission rates, the concentrations, and position of the thermal emission region for charge-carrier emission centers in nonabrupt p-n junctions. A computerized deep-level transient spectroscopy (DLTS) technique for current transients is used in combination with capacitance measurements. Numerical, iterative calculations of the shallow doping profile of the p-n junction and capacitance change connected with thermal emission of charge carriers from the emission centers are compared with measured data. Generalized expressions for the determination of carrier emission data from thermal current and capacitance transients are derived for nonabrupt p-n junctions. The method is applicable when the properties of the p-n junction cannot be chosen arbitrarily, for example, for the study of deep impurity centers in standard types of semiconductor devices where conventional DLTS methods fail.