Observation of a long-range electric drift of negatively charged vacancies in the space-charge regions of Au/n-Si Schottky diodes

Abstract

In-depth distributions of PsV and CiPs complexes formed in the space-charge regions of Au/n-Si Schottky diodes irradiated with fast electrons in a special electrical regime have been investigated. In the course of the irradiation the diodes were periodically driven into the reverse-bias state with square-shaped voltage pulses of fixed amplitude alternating with the forward-current pulses at a 2 MHz frequency. Non-flat profiles of PsV concentration have been revealed by deep-level transient spectroscopy measurements, while the interstitial defects been revealed by deep-level transient spectroscopy were found to have a constant density. The result is regarded as strong evidence for the long-range (approximately 0.1-1 mu m) field-assisted drift of negatively charged vacancies (V-) across the depleted region. The diffusion length of V- evaluated from the drift model (about (3.8+or-0.4)*10-2 mu m for the float-zone silicon used with a phosphorus content of 5*1015 cm-3) was found to be consistent with the value expected from the theory of diffusion-limited reactions.