Heterojunction Ultraviolet Photodetector Research Articles

A study on the spectral response of back-illuminated p-i-n AlGaN heterojunction ultraviolet photodetector

The spectral responses of back-illuminated p-i-n AlGaN ultraviolet photodetector under different bias voltage are investigated. The device structure is composed of p-GaN/p-Al0.3Ga0.7N/i-Al0.3Ga0.7N/n-Al0.6Ga0.4N and Ohmic contacts, where the p-GaN layer is very thin. There are two peaks in the spectral response of photocurrent located at 350 and 290 nm, respectively. It is found that in some devices the relative intensity and phase of these two peaks may change strongly with applied forward bias. A detailed analysis suggests that the possible Schottky-type-like behavior of metal and p-GaN contact and an unsatisfactory doping of p-GaN and p-AlGaN are responsible for the abnormal phenomenon.

ZnO nanorod arrays as p–n heterojunction ultraviolet photodetectors

Efficient front-illumination ultraviolet photodetectors have been developed using n-type ZnO nanorod arrays grown on p-type Zn0.9Mg0.1O-coated, (0001)-cut sapphire (Al2O3) substrate. Typical diode rectification behaviour and photoresponsivity were measured, revealing the photodetector's good sensitivity to incident UV photons and its new function of efficient light polarisation discrimination.

Backilluminated GaN/AlGaN heterojunction ultraviolet photodetector with high internal gain

We report on a backilluminated GaN/Al0.18Ga0.82N heterojunction ultraviolet (UV) photodetector with high internal gain based on metal-semiconductor-metal structures. A narrow band pass spectral response between 365 and 343 nm was achieved. When operating in dc mode, the responsivity reaches up to the order of 102 A/W under weak UV illumination, which is due to enormous internal gain up to 103. The linear dependence of photocurrent on bias and its square root dependence on optical power are found and explained by a trapping and recombination model. The high photocurrent gain is attributed to trapping and recombination centers with an acceptor character induced by dislocations in GaN.