High-Performance 4H-SiC p-i-n Ultraviolet Photodiode With p Layer Formed by Al Implantation

In this letter, a high-performance 4H-SiC p-i-n ultraviolet (UV) photodiode (PD) with its p layer formed by Al implantation is designed and fabricated. The dark current density of the PD remains lower than 1 nA/cm2at -100 V in the entire temperature range from room temperature (RT) up to 175 °C. The RT maximum external quantum efficiency of the PD under 0 V bias is 44.4% at 270 nm with a UV/visible rejection ratio larger than 104. The photoresponse characteristics of the PD are studied as the functions of reverse bias and temperature, which suggest that the device is advantageous to detect UV signals in high-temperature harsh environment. Compared with a 4H-SiC p-i-n PD formed entirely by epitaxial growth, the PD formed by Al implantation exhibits larger frequency dispersion in capacitance-voltage measurement, which should be caused by residual structural defects introduced during the ion implantation process.