Long-wavelength acoustic-mode-enhanced electron emission from Se and Te donors in silicon.

Abstract

An enhancement of the thermal emission rates from Se and Te double donors in silicon was observed by applying external vibrational excitation in the MHz frequency range. The excitation was performed either by resonant sample vibrations at frequencies of the lowest eigenmodes or by Lamb waves in a plate. Emission rates were measured by using both deep-level transient spectroscopy and single-shot capacitance techniques. Possible explanations for the observed enhancement of the emission rates are either thermal disturbances due to thermoelastic losses of mechanical energy or nonlinear effects in conjunction with oscillating stresses in solids. Our data are inconsistent with possible thermal disturbances. A tentative model is therefore proposed, suggesting that changes in the equilibrium position of impurity atoms exhibiting low-frequency oscillations yield enhanced emission rates. These changes depend upon the local surrounding of the impurity atoms and ``hardness'' of the interatomic interaction rather than the strength. Vibrational perturbations as discussed in this paper may be an effective tool to obtain new information on defects in solids.