The spectral response of metal-semiconductor-metal (MSM) and Schottky barrier photodiodes have been studied in the near- and vacuum ultraviolet (VUV). Devices were fabricated on micro-epitaxial lateral overgrowth GaN layers, which presented dislocation densities as low as Experimental results indicate that the surface properties become critical for the optical response at short wavelengths. Schottky barrier photodiodes showed a lower VUV sensitivity than MSMs as a result of the radiation absorption in the semitransparent Au top-layer. However, Schottky photodiodes yielded a better time stability operating in photovoltaic mode. For photon energies above 10.5 eV, the quantum efficiency of the MSM photodiodes was enhanced as a consequence of the different nature of light-semiconductor interactions, which provoke a decrease of the absorption coefficient and the generation of multiple electron-hole pairs for each impinging photon. The ionization energy for GaN has been also estimated.
Response of ultra-low dislocation density GaN photodetectors in the near- and vacuum-ultraviolet
J. L. Pau, C. Rivera, E. Muñoz, E. Calleja, U. Schühle, E. Frayssinet, B. Beaumont, J. P. Faurie, P. Gibart; Response of ultra-low dislocation density GaN photodetectors in the near- and vacuum-ultraviolet. J. Appl. Phys. 15 June 2004; 95 (12): 8275–8279. https://doi.org/10.1063/1.1748855
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