Optoelectronic characterization of Au/Ni/n-AlGaN photodiodes after annealing at different temperatures

The optoelectronic characteristics of Ni/Au Schottky photodiodes based on Al0.35Ga0.65N were investigated. The transmission of the Ni (50Å)/Au (50Å) layer was determined by evaporating it on a quartz substrate. As evaporated, the transmission coefficient in the 200–350nm wavelength range was found t...

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Bibliographic Details
Published in:Physica. B, Condensed matter Condensed matter, 2012-05, Vol.407 (10), p.1628-1630
Main Authors: Ngoepe, P.N.M., Meyer, W.E., Diale, M., Auret, F.D., van Schalkwyk, L.
Format: Article
Language:English
Subjects:
AlGaN
Annealing
Coefficients
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Evaporation
Exact sciences and technology
Gold
Nickel
Optoelectronics
Photodiodes
Physics
Schottky photodiode
Surface double layers, schottky barriers, and work functions
Wavelengths
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Summary:The optoelectronic characteristics of Ni/Au Schottky photodiodes based on Al0.35Ga0.65N were investigated. The transmission of the Ni (50Å)/Au (50Å) layer was determined by evaporating it on a quartz substrate. As evaporated, the transmission coefficient in the 200–350nm wavelength range was found to be 43 to 48%. Annealing at temperatures of up to 400°C did not influence the transmission coefficient. After annealing at 500°C, the transmission coefficient increased from 50 to 68% over the 200–350nm range. The reverse bias current was optimised in terms of annealing temperature and was found to be as low as 1.94×10−13A after annealing at 400°C for a 0.6mm diameter contact. The Schottky barrier heights increased with annealing temperature reaching as high as 1.46 and 1.89eV for I–V and C–V measurements, respectively. The quantum efficiency was measured to be 20.5% and the responsivity reached its peak of 0.046A/W at 275nm. The cut-off wavelength was 292nm.
ISSN:0921-4526
1873-2135
DOI:10.1016/j.physb.2011.09.102