A beneficial radiation response is observed in CMOS devices fabricated in-an inherently degraded silicon heteroepitaxy layer grown upon sapphire substrates. The lattice mismatch between the layer and the substrate is sufficiently different as to result in defects in the layer near the silicon/sapphire substrate. Because of this, silicon-on-sapphire (SOS) architectures are often selected to fabricate radiation-hardened integrated circuits, such as very large scale static random access memories. The defect level of the silicon overlayer can be characterized and controlled by means of ultraviolet (UV) light reflectance, an indirect quantification of the defect twins which produces the favorable response. An identified range of defect densities has been found to aid in reducing the post irradiation leakage of the N-channel transistor and is characterized by a relatively high ultraviolet reflectance (UVR) index or number. Integrated circuit designs such as static RAMs which employ a predominance of N-channel transistors enjoy a significant reduction in leakage current in a radiation environment. On the other hand, this same level of crystal quality produces a correspondingly inferior increase in P-channel transistor leakage. Because of this apparent disparity, a compromise between N and P-channel device leakage is usually encountered. Such a compromise necessarily favors suppression of leakage in the N channel transistor, often allowing the P-channel leakage component to become excessive.