The transmission enhancement of microwave radiation through subwavelength apertures in metallic structures with double-sided gratings was analyzed. It was observed that the structures displayed enhanced transmission around surface plasmon resonance frequencies. It was also observed that the normalized transmission decreased sharply with increased reception angle. It was found that the grating structures exhibited best results with ∼50% transmission at 20.7 mm, enhancement factor of ∼25 and ±4° angular divergence

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Changing the ratio of carbon to silicon during the epitaxial 4H–SiC growth is expected to alter the dominant deep level trap, which has been attributed to a native defect. The C∕Si ratio was changed from one to six during epitaxial growth of SiC. Diodes fabricated on the epitaxial layer were then characterized using current-voltage and deep level transient spectroscopy. The single peak at 340K (Z1/Z2 peak), was deconvolved into two traps, closely spaced in energy. The concentration of one of the Z1/Z2 traps decreased with increasing C∕Si ratio. This result opposes theoretical predictions of carbon interstitial components, and supports assignment to a silicon antisite or carbon vacancy relationship. The concentration of the second component of the peak at 340K did not depend on the C∕Si ratio, which would indicate an impurity in an interstitial site.

A series of n-ZnO/p-6H–SiC heterostructures have been grown by molecular-beam epitaxy, and electrical and optical properties of the mesa diodes have been studied. Current versus voltage (I–V) characteristics of the samples revealed a good rectifying behavior of all samples with a typical leakage current less than 10-7 A at -8, and with forward currents changing from sample to sample and at 8 V lying in the range 0.8–10 mA. Capacitance–voltage (C–V) profiles and double pulse deep level transient spectroscopy (DDLTS) indicate interface states in the 1012–1013/cm2 eV range, sharply peaked below 0.5 eV. Under forward bias electroluminescence (EL) emission was observed from most of the samples in yellow and violet regions with maxima at ∼2.1 and ∼2.92 eV, which attributed to the SiC side of the n-ZnO/p-6H–SiC heterojunction, from the comparison with the photoluminescence spectra of n-ZnO and p-SiC.

High-quality Schottky junctions have been fabricated on n-type 4H SiC epitaxial layers grown by chemical-vapor deposition on C-and Si-face substrates in order to understand the effect of growth direction on the growth mechanism and formation of defects. Atomic force microscopy analysis showed dramatic differences between the surfaces of SiC epilayers grown on C and Si faces. There was a significant step bunching in the SiC grown on Si-face substrates. Current-voltage, capacitance-voltage, and deep-level transient spectroscopy ͑DLTS͒ measurements were carried out on the Schottky junctions to analyze the junction characteristics. The Schottky junctions on C-face SiC showed larger barrier heights than those on Si-face SiC, showing that each face has a different surface energy. The barrier heights of Ni Schottky junctions were found to be 1.97 and 1.54 eV for C-face and Si-face materials, respectively. However, the deep-level spectra obtained by DLTS were similar, regardless of the increased surface roughness of the Si-face 4H SiC.