ABSTRACT
We have seen how the response function F(E) is influenced to an inordinate degree by the physics taking place at the front contact of the semiconductor x-ray detector. Incomplete charge collection (ICC) results from the escape to the contact of what may be termed ‘hot’ electrons (primary Auger and photoelectrons and their immediate progeny), ‘warm’ electrons (the high energy tail to the distribution at the end of the cascade process), and ‘thermal’ electrons in energetic equilibrium with the crystal lattice after the outward diffusion of the charge cloud. Furthermore, ‘hot’ electrons from the metal contact are sprayed into the semiconductor adding background events. All these effects are undesirable from a spectroscopic perspective, so we must address the topic of how to eliminate or reduce them. There have been many theoretical discussions on semiconductor surfaces and interfaces (e.g., see Monch [1]), and the topic of contacts can be as complex and deep as you wish to make it. And yet, we still believe that certain aspects are not well understood. We therefore make the caveat at this point that, in what follows, some of the explanations proposed are the authors’ own ideas based on many years of experimentation with various contacts to silicon, germanium, and CdZnTe.
