Session B11 - Optical Spectroscopy of Semiconductors - II.
ORAL session, Monday midday, March 22
510D, Palais des Congres
Collective impact ionization has been used to explain lock-on, an optically-triggered electrical breakdown occurring in some photoconductive semiconductor switches (PCSS's). One aspect of lock-on is that it occurs in GaAs and InP PCSS's, but, so far, it has not been observed in Si or GaP PCSS's. In this presentation, a rate equation implementation of collective impact ionization is discussed which leads to new insights both about intrinsic electrical breakdown in insulating materials in general and about lock-on specifically. In this approach, lock-on and electrical breakdown are steady state processes controlled by competition between carrier generation and recombination. This leads to theoretical definitions for both the lock-on field and the breakdown field. Our results show that lock-on is a carrier-density dependent form of electrical breakdown which exists in principle in all semiconductors. We show that its observation or the lack thereof is dependent on the difference between the breakdown and lock-on fields. Results for GaAs, InP, Si, and GaP will be discussed.