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Pd/Ti/Al and Ti/Al Ohmic contact materials on Ga-face and N-face surfaces of n-type GaN were investigated by measuring the contact resistivities with respect to annealing temperatures. Pd/Ti/Al contact showed good Ohmic property in contrast to Ti/Al contact on N-face surface of n-type GaN. Cross-sectional transmission electron microscopy results on samples of as-deposited and annealed at 450 °C for 30 s indicated that Pd played an important role in changing the surface state of N-face surface of n-type GaN and less than 50 Å of Pd was required to obtain the best Ohmic contact property. [ABSTRACT FROM AUTHOR]

An electrically injected InGaN/GaN-based distributed Bragg reflector (DBR) laser was demonstrated. Surface grating was formed on both sides of ridge waveguide by chemically assisted ion beam etching technique. The observed threshold current was 375 mA with threshold voltage of 15.1 V for 500x3 μm[sup 2] devices. The emission of the DBR laser occurred in a single longitudinal mode at a wavelength of 401.3 nm. The ratio of sidemode suppression was found to be more than 13 dB until a current injection of 1 A. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]