Effects of annealing treatment on the high temperature performance of 4H-SiC metal-semiconductor-metal ultraviolet photodiodes

The high temperature performance plays a crucial role in the high-temperature harsh environment detection. In this paper, the electrical and optical characteristics of 4H-SiC metal-semiconductor-metal (MSM) ultraviolet photodiodes (PDs) were investigated at high temperatures. The C-V measurement indicates that the 4H-SiC Schottky barrier diode is partially depleted at 40 V bias. Analysis of I-V data based on the thermionic emission theory demonstrates that the annealing treatment at 400 degrees C can effectively improve the homogeneity of Ni/4H-SiC Schottky barrier height. Experimental results confirm that the annealing treatment is beneficial not only to reduce the dark current and improve the photoresponse, but also to enhance the sensitivity for 4H-SiC MSM PDs. The sensitivity of 400 degrees C annealed MSM PDs (6.2 x 10(3)) is five times larger than that of as-deposited MSM PDs (1.3 x 10(3)) at 200 degrees C.