or a given amount of adsorbed dose, irrespective of the radiation source. The radiation effects community has examined this assumption for several important cases, for example, the equivalence of 10 keV x-rays and Co-60 dose and the role of secondary electronic equilibrium at material interfaces. In the following paragraphs, we consider two microdosimetry issues that are specific to proton dose. 3.2.1 Lateral nonuniformities (LNUs): The term LNU in the context of radiation damage in MOS transistors describes the nonuniform distribution of holes in gate oxides. The initial papers addressing the phenomenon are cited in [Frie-88]. This paper describes a detailed investigation of the causes and effects; especially the false indication of interface state production using the subthreshold method when applied under cryogenic conditions. All of the initial work assessed the role of LNUs in gate oxides that were exposed to either Co-60 gamma rays or 10 keV x-rays. In the paper by Frietag, et al., a statistical formalism for the analysis of microscopic fluctuations in dose was introduced and applied to describe the behavior of the subthreshold current. The following year the microdosimetry formalism from [Frie-88] was invoked and modified to treat the problem of LNUs arising from proton damage using a two component model [Xaps-89]. Conceptually, the problem of nonuniform dose deposition from protons might be suspected to cause significant effects when small geometries are considered such as in thin gate oxides. After all, there is a track structure, at least in the initial dose deposition. While the data and analyses presented in [Xaps-89] do demonstrate measurable effects in sub- threshold leakage current stretch-out at 77° K, perhaps the most remarkable result of this body IV-19 of work lies in the fact that, at least to first order, the microdosimetric fluctuations in ionizing dose deposition from protons are unimportant to satellite electronics. 3.2.2 Electron-Hole Recombination: This issue concerns the fate of the ele