Scaling and Modeling of High Temperature 4H-SiC p-i-n Photodiodes

4H-SiC p-i-n photodiodes with various mesa areas (40 000 μm2, 2500 μm2, 1600 μm2, and 400 μm2) have been fabricated. Both C-V and I-V characteristics of the photodiodes have been measured at room temperature, 200 °C, 400 °C, and 500 °C. The capacitance and photo current (at 365 nm) of the photodiodes are directly proportional to the area. However, the dark current density increases as the device is scaled down due to the perimeter surface recombination effect. The photo to dark current ratio at the full depletion voltage of the intrinsic layer (-2.7 V) of the photodiode at 500 °C decreases ~7 times as the size of the photodiode scales down 100 times. The static and dynamic behavior of the photodiodes are modeled with SPICE parameters at the four temperatures.