Abstract
Nonmonotonic current transients at constant temperature, following a pulsed charge injection, have been observed in silicon diodes heavily irradiated with gamma rays. The features of the transients have been studied at different temperatures and using various reverse biases. The particular shape of the measured transients is interpreted, with the help of numeric simulations, in terms of a strong time dependency of the space charge density due to the discharge of radiation induced deep traps. In particular, a nonmonotonic transient is generated if the discharge of a dominant trap determines the change of the space charge sign (type inversion). In this case the active volume of the sample, from which the current is collected, is increased during the discharge and causes the sample to become fully depleted for a short time. During this time interval the active volume reaches its maximum value and a peak is produced in the transient shape. The measurement of this peak provides a sensitive way to detect type inversion in semiconductor devices and to determine the responsible energy levels. The correlation of nonmonotonic transients with thermally stimulated current spectra and the distortion produced in deep level transient spectroscopy spectra are discussed in detail.
4 More- Received 25 March 2004
DOI:https://doi.org/10.1103/PhysRevB.70.195209
©2004 American Physical Society