(1) University of Glasgow, Glasgow, G12 8QQ, Scotland
(2) Rutherford Appleton Laboratory, CCLRC, Didcot, England, UK, OX11 0QX
AlGaN and GaN have been investigated as UV detector materials for applications in protein structure studies. I-V characteristics performed on the material using concentric contacts showed 4 orders of magnitude greater dark current for the Al(0.1)Ga(0.9)N than for the GaN. Subsequently, interdigitated metal-semiconductor-metal (MSM) photodetectors were successfully fabricated on GaN. No changes in levels of dark surrent were recorded using varying metal electrodes with similar work functions (Pd and Au). The unbiased diodes showed a difference of 3 orders of magnitude between dark and photocurrent levels on exposure to UV. The responsivity for diodes with 25 and 100 micron finger separation operated in unbiased mode was around 100mA/W and was flat over the bandgap. These results show a responsivity in agreement with those from previous measurements for biased GaN photodetectors {1}. Using these results, a design for an unbiased GaN detector to be used for protein structure studies is proposed
International Workshop on Radiation Imaging Detectors 2004
25-29 Jul 2004, Glasgow, UK