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The effects of reactor pressure on epitaxial lateral overgrowth (ELO) via low-pressure metalorganic vapor phase epitaxy (MOVPE) have been studied in relation to growth temperature. For the ELO GaN on SiO2 stripes along the <1100> direction of the underlying GaN, on decreasing the reactor pressures from 500 to 40 Torr or increasing the growth temperatures from 950 to 1050°C, the (0001) surfaces become broad and the side walls changed from inclined {1122} surfaces to vertical {1120} surfaces. For the ELO GaN on the stripes along the <1120> direction, the shapes with {1101} facets are independent of the reactor pressure and growth temperature. The ELO of GaN is dominated by the diffusion-limited process.

The characterization of Schottky type ultraviolet (UV) detectors with transparent electrode between vacuum ultraviolet (VUV) and visible light region using synchrotron radiation is described. The responsivity spectrum of the detectors at 0 V bias was obtained in the wide range between 2 eV (563 nm) and 25 eV (50 nm). The photoemission current from Au electrode was able to be canceled by improving the measuring circuit, and thus we succeeded in operating the detectors without any photoemission current from Au and GaN. The responsivity of the detectors is about 0.15 A/W at 3.5 eV. These results show that these Schottky type detectors with the transparent electrode are effective to detect VUV-UV light (50-360 nm, 3.4-25 eV) without any photoemission.