Fast Switching 4H-SiC P-i-n Structures Fabricated by Low Temperature Diffusion of Al

Abstract

P-i-n 4H-SiCAl diode structures are fabricated by a new approach which is low temperature diffusion of aluminium (Al) in SiC using flow of vacancy defects from surface into volume of crystal. In conventional diffusion in SiC, the operating temperature is usually >2050°C while, in this approach, the diffusion temperature is between 1150 and 1300°C. As the conditions of formation of junction in this method essentially differ from conventional diffusion (low temperature and process of diffusion are accompanied by forming structure defects), it is interesting to identify the advantages and disadvantages of a new method of diffusion. Fabricated p-i-n structures have low breakdown voltage between 80 and 140 V (due to the influence of dislocations and micropipes) and are capable of operating at temperatures up to 300°C. Structure has fast switching time and duration of the reverse recovery current less than 10 ns. We believe that because of low diffusion temperature, the concentration of nitrogen related trapping levels is relatively low and as a result the fast switching time is observed in our samples. It has been shown that this low temperature diffusion technology can be used to fabricate p-region and high resistive i-region of SiC diode in single-step process.