Multiband GaN/AlGaN UV Photodetector
K.P. Korona, A. Drabińska, K. Pakuła and J.M. Baranowski
Institute of Experimental Physics, Warsaw University, Hoża 69, 00-681 Warsaw, Poland
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Received: 17 06 2006;
We present optical and electrical measurements made on GaN/AlGaN photodetector structure capable to detect three UV ranges, tuned by external voltage. The highest band at energy of about 3.85 eV is nearly independent of bias applied to the Schottky contact. Photosensitivity of the second band at about 3.65 eV changes strongly with the bias. Signal in this range increases about 20 times when the bias changes from 0 V to -4 V. Photosensitivity of the third band (3.4 eV) appears for strong reverse bias (-3 V). Characteristics of the detector are in qualitative agreement with numerical model, however deep centers present in the AlGaN layers cause quantitative discrepancies. The concentration of defects of the order of 1016 cm-3 was estimated from current transients.
DOI: 10.12693/APhysPolA.110.211
PACS numbers: 72.40.+w, 73.61.Ey, 73.40.Kp