Precise control and modulation of fluorescent sunlamps are necessary for ecologically valid simulation of solar UV‐B (280‐320 nm) radiation enhancement which would correspond to ozone reduction. A control system is described which allows lamp emittance to be modulated over a large dynamic range (50:1), permits stable lamp operation and starting at low temperatures, and provides a sensitive feedback loop to compensate for both atmospheric conditions, such as cloud cover, as well as changes in radiant emittance from the lamps resulting from factors such as temperature and lamp age.

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In this work, a deep level transient spectroscopy (DLTS) study on n-type epitaxial cubic silicon carbide grown on Si substrates has been performed. The results of this study indicate the presence of at least two majority-carrier traps. One trap (SCE1) is located 0.34 eV from the conduction-band edge; the other trap (SCE2) is located 0.68 eV from the conduction-band edge. These two traps have concentrations of approximately 1×1015 cm−3. The DLTS spectrum as a function of the surface treatment of the SiC has been investigated. The results of this investigation indicate that one of the levels (SCE2) appears to be formed as a result of high-temperature thermal oxidation.