AVS 46th International Symposium
    Electronic Materials and Processing Division Monday Sessions
       Session EM-MoA

Paper EM-MoA1
GaN-Based Diode Structures for Optoelectronic Applications in the Near Ultraviolet Range of the Spectrum

Monday, October 25, 1999, 2:00 pm, Room 608

Session: Nitride Processing and Characterization
Presenter: D. Starikov, University of Houston
Authors: D. Starikov, University of Houston
I.E. Berishev, University of Houston
N. Badi, University of Houston
N. Medelci, University of Houston
J.-W. Um, University of Houston
A. Bensaoula, University of Houston
Correspondent: Click to Email
We have previously reported that spectrally matched n-SiC and n-GaN-based Shottky barrier diode structures with semi-transparent Au electrodes can be employed for optoelectronic applications in the UV range of the spectrum. Both n-SiC-based and n-GaN-based structures indicated photosensitivity in the range down to 220 nm. The SiC- based structures exhibited optical emission in the avalanche mode at reverse bias down to 300 nm. The avalanche emission from the n-GaN-based samples was unstable and lasted only few seconds. In addition, high dark current and low thermal stability have been observed due to the absence of good ohmic contacts and satisfactory insulation, and poor mechanical and thermal stability of the gold layers. In this work Schottky barrier diode structures were fabricated on p-type GaN layers grown on sapphire using solid metal electrodes. The structures exhibit blue and wide-spectrum optical emissions at forward and reverse bias, respectively, and photo sensitive properties at no bias. Spectra of wide-spectrum optical emission and photo sensitivity measured through the sapphire substrate and 1.5 mm GaN film are matched in the range of 365-400 nm. The Lambertian radiant UV power of the blue emission is 466 mW at 22 V. Employment of wide-band gap oxide semiconductors In@sub 2@O@sub 3@ and SnO@sub 2@ for rectifying contact fabrication in our diode structures should extend the spectral range of our devices beyond 365 nm (the wavelength corresponding to the band gap of GaN) and improve their mechanical and thermal stability. We have incorporated these UV-transparent and electrically-conductive oxide semiconductor materials in our device structures. Our results from the various processing steps (patterning, etching, isolation and contact deposition), as well as from the diode structures characterization will be presented. Perspectives for applications of these structures in chemical sensors are discussed.