PURPOSE: To obtain a pnpn semiconductor element wherein its bias control and its resetting are performed by light and to obtain its drive circuit by a method wherein electrodes are installed in individual pnpn layers having a direct transmission-type pnpn structure and reflecting mirrors composed of a semiconductor multilayer film are formed on their upper and lower parts.

CONSTITUTION: Semiinsulating GaAs is used as a substrate 25 as well as the upper part and the lower part of a p-type, n-type, p-type and n-type AlGaAs/ GaAs laminated structure 11 are sandwiched between multilayer-film reflecting mirrors 12, 14 in which GaAs films and AlAs layers having a thickness of λ/4n have been laminated alternately. An element is formed to be a mesa shape by two etching processes, an anode electrode 21 is formed on a p-type multilayer reflecting mirror, an n-gate electrode 22 is formed on an n-type AlGaAs film and, in addition, a diffused region 26 which reaches a p-type GaAs layer by diffusing p-type impurities is formed on an n-type AlGaAs film. Consequently, when a p-type gate electrode 23 is formed on it and a cathode electrode 24 is formed on an n-type semiconductor multilayer film on a second step, a drive circuit whose bias control and resetting are performed by light can be realized by using a transistor having a pnpn structure.