Nanometer-scale InGaN self-assembled quantum dots (QDs) have been prepared by growth interruption during metalorganic 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 QD density was about 2 x 10(10)cm(-2). In contrast, much larger InGaN QDs were obtained without growth interruption. InGaN metal-semiconductor-metal photodiodes with and without QDs were also fabricated. It was found that the QD photodiode with lower dark current could operate in the normal incidence mode, and exhibit a stronger photoresponse. (C) 2004 American Vacuum Society.