Characteristics of GaN-based p-i-n photodetector at low temperature and performances of MCT/GaN-based infrared/ultraviolet dual-colour detector

Abstract

The performances of GaN-based p-i-n photodiode at low temperature are studied. The current-voltage characteristics at different temperatures were measured. The turn-on voltage of GaN-based p-i-n detector decreases from 3.7 V to 3.0 V as temperature increases from 91 K to 286 K. The series resistance and ideality factor of the GaN-based detector is calculated. Values of series resistance are 1508 Ω, 453 Ω, 353 Ω and 295 Ω, at 91 K, 174 K, 224 K and 286 K, respectively .The values of ideality factors are 43.7, 15.4, 12.6 and 11.9, respectively. The spectral response of GaN p-i-n photodiode was measured at different temperature .The results show that with the temperature decreasing, the peak response wavelength gets shorter, and the responsibility gets smaller. The structure of ultraviolet/infrared MCT (mercury cadmium tellurium)/ GaN-based dual-colour detector is designed. MCT medium wave photovoltage photodetector is employed in dual-colour detector. The responsivities of GaN-based detector and MCT-based detector were measured. The dual-colour device can realize the detection of the light between 240 nm and 330 nm, and light between 3.2 μm and 5.8 μm.