The invention provides a double-injection
avalanche transistor and a preparation method thereof, which can solve the problems that the conduction
voltage drop and loss of the existing
avalanche transistor are relatively high because the existing
avalanche transistor needs to maintain a
high field intensity collision
ionization region, and the performance of the existing avalanche
transistor is influenced by temperature rise caused by
conduction loss under repetition frequency operation. The
transistor comprises a collector region n + substrate layer, a collector region n0 epitaxial layer, a p-type base region layer, an n + emitter region layer, a plurality of p + field rings and a collector region p + injection layer arranged between the collector region n + substrate layer and the collector region n0 epitaxial layer, a plurality of first ring grooves are formed in the top of the collector region n0 epitaxial layer, the p + field rings are arranged in the first ring grooves, and the tops of the p + field rings are flush with the top of the collector region n0 epitaxial layer. The p +
doping concentration of the collector region p + injection layer is greater than the n +
doping concentration of the collector region n + substrate layer, the n +
doping concentration of the n + emitter region layer is greater than the p-type doping concentration of the p-type base region layer, and the n + doping concentration of the n + emitter region layer and the p + doping concentration of the p + field ring are the same
order of magnitude as the n + doping concentration of the collector region n + substrate layer.