GB841847A - Improvements in or relating to semi-conductor devices - Google Patents

Abstract

841,847. Semiconductor devices. PHILIPS ELECTRICAL INDUSTRIES Ltd. April 18, 1956 [April 21, 1955], No. 11796/56. Drawings to Specification. Class 37. In a semiconductor device comprising two semiconductor regions of different conductivity types separated by a rectifying junction, one of which regions comprises a buffer layer not thicker than half the diffusion length therein but thicker than twice the Debye Huckel length, a reflector layer is provided on the side of the buffer layer remote from the junction at least twice as thick as the buffer layer and having a resistivity at least three times less than that of the buffer layer. A connection is provided to the buffer-layer but the reflector is free of connections. The Specification shows that such a rectifying junction exhibits an emitter efficiency comparable with that of a normal junction between an emitter consisting of material of the same resistivity as the reflector layer and a base zone of the same material as the other zone. At the same time it possesses the low capacity and high breakdown voltage associated with a junction between an emitter or collector of material of the same resistivity as the buffer layer and a base zone of the same material as the other zone. The reflector layer may be of the same conductivity type as the buffer or of the opposite type. In the embodiment a junction transistor comprises an N type base zone and emitter and collector zones each consisting of a buffer layer and reflector layer with dimensions and resistivities as specified above. The emitter and collector connections are made to the respective buffer layers of the zones and the reflectors left floating. The invention is also said to be applicable to rectifier and photoelectric cells.