The High Performance of 4H-SiC for the Photodetector in High-speed Optocoupler

In this letter, a high-performance photodetector was established with the 4H-SiC structure for the high-speed optocoupler. It is found that the band gap of the doped 4H-SiC is reduced, where the electrons can transmit to the conduction band easier. It improves the photoelectric response speed and the light absorption rate of the system is effectively improved. Under the 840nm incident light, the transient response of the optocoupler are 210ns and 155ns, respectively. During the temperature changed, the maximum variation value is 12ns. The response speed of the whole chip is increased and it changed very little with the variation of the input photocurrent and the operation temperature.