Degradation of AlGaN-based metal-semiconductor-metal photodetectors
Jpn. J. Appl. Phys., vol. 58, no. SC, pp. SCCC21 (2019).
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The degradation of AlGaN-based metal-semiconductor-metal photodetectors under UV illumination has been studied. Oxidation triggered by the presence of moisture and mobile carriers at the semiconductor surface was found to be the degradation mechanism. UVC devices with Al0.5Ga0.5N absorbers show stable performance for more than 1000 h at intensities around 10 mW cm-2 and low dark current when passivated after metallization by SiNx. UVB devices with Al0.25Ga0.75N absorber layers were found to be more sensitive and here additional protection by a thin SiN layer grown in situ in the MOVPE growth chamber against any contamination yielded stable devices. As a result now stable UVB and UVC detectors with high external quantum efficiency, low dark current and no indications for persistent photocurrent are available.
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin, Germany