Nitride-based light emitting diode and photodetector dual function devices with InGaN/GaN multiple quantum well structures

In this paper, a InGaN/GaN multiple quantum well structure commonly used for light emitting diodes has been employed for dual functions of optoelectronics devices exhibiting photodetector properties in reverse bias, while at the same time preserving the distinct identities of LED in forward bias. The turn on voltage in forward bias and the breakdown voltage in reverse bias were about 3.2 V and −30 V, respectively. The higher photo- and dark-current densities were detected for larger size of devices. The contrast ratio calculated between photo- and dark-current densities of large-size device decreases more rapidly as compared to that of a small-size device. Thus, one can easily integrate photodetectors with LEDs using the same epi-structure to realize a GaN-based optoelectronic integrated circuit (OEIC).