Current transient spectroscopy: A high-sensitivity DLTS system

Abstract

A deep-level transient spectrometer (DLTS) has been built that measures current transients, rather than the usual capacitance transients, in p-n junctions. The system was developed to optimize sensitivity for the study of low-concentration processing-induced defects. An analysis of its performance as a function of timing parameters is presented. A noise analysis of both capacitance and current transient measurement is presented, showing that neither method has an inherent sensitivity advantage, and that both should be capable of detection limits of about 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> of the shallow doping concentration. Noise measurements indicate that a detection limit of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> times the doping has been obtained. Spectra of a processed p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -n diode with no intentional contamination show several defect levels in the 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</inf> , or 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , range. Spectra of gold-doped p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -n diodes yield emission data in good agreement with accepted values.