Analysis of High-Temperature Carrier Transport Mechanisms for High Al-Content Al0.6Ga0.4N MSM Photodetectors

An AlGaN-based solar blind ultraviolet (UV) metal–semiconductor–metal (MSM) photodetector (PD) with a high Al-content of 0.6 has been successfully fabricated. The device exhibits a cutoff wavelength of 255 nm corresponding to the sharp cutoff transmission spectrum of Al
_0.6
Ga
_0.4
N. In addition, dislocations in the Al
_0.6
Ga
_0.4
N epi-layer has been analyzed by high-resolution transmission electron microscope (TEM). The Al
_0.6
Ga
_0.4
N-based solar blind PD exhibits a responsivity of 0.51 A/W at 10 V with a high breakdown voltage of 470 V. Suggesting its potential applications for high-temperature solar blind UV detection, the
${I}$
–
${V}$
–
${T}$
characteristics have been comprehensively investigated to explore its high-temperature carrier transport mechanisms. It is convincingly demonstrated that the bias leakage current across the device is dominated by thermionic-field emission transport at low bias voltages and Poole–Frenkel emission at high bias voltages from room temperature up to 425 K.