InGaN photodiodes using CaF2 insulator for high-temperature UV detection

The authors report on a thermally‐stable ultraviolet‐A photodiode using CaF2 as the insulation layer in the metal‐insulator‐semiconductor (MIS) structure based on a high‐quality InGaN film. Compared to the Schottky photodiode (SPD) without the insulator, the MIS‐SPD device maintains a low reverse leakage current, a high photo‐to‐dark current ratio and fast response at the temperature as high as 523 K, indicating CaF2 as a good candidate for the III‐Nitride devices. The overall photoresponse properties of the MIS‐SPD are governed by the metal/insulator/semiconductor interfaces. The photocurrent gain at reverse biases from room‐temperature to 463 K is interpreted in term of thermionic‐field emission (TFE) and field emission mechanism, while TFE becomes the dominant mechanism at higher temperatures (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)