InGaN/GaN multiquantum, well (MQW) p-n junction photodetectors with semi-transparent Ni/Au electrodes were fabricated and characterized. It was found that the fabricated InGaN/GaN MQW p-n junction photodetectors exhibit a 20 V breakdown voltage and a 3.5 V forward 20 mA turn on voltage. It was also found that the photocurrent to dark current contrast ratio is higher than 10(5) when a 0.4 V reverse bias was applied to the InGaN/GaN MQW p-n junction photodetectors. Furthermore, it was found that the maximum responsivity was 1.28 and 1.76 A/W with a 0.1 and 3 V applied reverse bias, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.