Silicon carbide (SiC) has shown considerable potential for ultraviolet (UV) photodetectors due to its properties such as wide band gap (3.26 eV for 4H-SiC), high break down electric field and high thermal stability. 4H-SiC-based UV photodetectors such as Schottky, metal-semiconductor-metal (MSM), metal-insulator-semiconductor (MIS) and avalanche have been presenting excellent performance for UV detection application in flame detection, ozone-hole sensing, short-range communication, etc. Generally, the most widely used antireflection coating and passivation layer for 4H-SiC-based photodetectors are native SiO2 grown by heating 4H-SiC in O2 in order to improve the absorption and passivation of photodetectors. Nevertheless, the thermally grown SiO2 single layer suffers from high reflection, large absorption and inaccurate thickness. Therefore, in this chapter, UV antireflection coatings were designed, fabricated and applied in order to reduce optical losses and improve the quantum efficiency (QE) of 4H-SiC-based photodetectors. The important results will be introduced as follows:
Part of the book: Advanced Silicon Carbide Devices and Processing