Degradation processes and origin in InGaN-based high-power photodetectors

GaN-based multi-quantum well devices are promising candidates as photodetectors in the UV to visible spectral range. Their complex structure and the extreme input optical power density still poses problems of reliability. In the devices under test, degradation takes place when the optical power density reaches values higher than 44 W/cm(2), and consists in a reduction in the efficiency of the device and in its output current. This degradation process is not sudden and is caused by a gradual increase in the defect concentration, detected by means of photocurrent spectroscopy experiments, that suggest the role of gallium vacancies and/or their complexes as the physical origin. A secondary effect is the reduction in open circuit voltage, likely originating from an improvement in dopant and/or contact quality.