Nanometer-scale InGaN self-assembled quantum dots (QDs) have been prepared by growth stop during the metal-organic chemical vapor deposition growth. With a 12 s growth interruption, We Successfully formed InGaN QDs with a typical lateral size of 25 nm and an average height of 4.1 nm. The QDs density was about 2 x 10(10) cm(-2). Nitride-based QD metal-semiconductor-metal (MSM) photodetectors were also fabricated. It wits found that We Could significantly enhance the photocurrent to dark current contrast ratio of the MSM photodetectors by the use of QD Structure. (C) 2003 Elsevier Ltd. All rights reserved.