THEORETICAL-MODEL FOR HOLE CAPTURE AT ACCEPTORS IN GERMANIUM

Experimental results on hole capture in germanium are reviewed. good agreement is found not only among various investigators for the same center, but among different acceptors regardless of charge state. For these acceptors, the capture cross section depends only on temperature (is-proportional-to T-1). Collision theory is used to transform temperature dependence to wave-vector dependence, sigma = pi/k2. This is equal to the s-wave component of the incident plane wave decomposed into polar coordinates by partial wave analysis. It is proposed that direct capture into the ground state exceeds cascade capture for T > 3 K for capture at singly ionized acceptors and for T > 11 K for capture at doubly ionized ones.