Field-effect bipolar lateral transistor

The application of lateral transistors to silicon integrated circuits has been reported by H. C. Lin et al. The current gain of such a lateral transistor is generally low due to the relatively wide base width as compared to a double-diffused planar transistor. However, under proper conditions, the current gain can be controlled by a field-effect electrode across the base region. This paper describes the characteristics and the mechanism of operation of this device. The structure of the device consists of two diffused junctions side by side and a thin oxide layer which is covered by a metallic layer over the base region between the collector and the emitter. The field-effect electrode controls the surface recombination in the base region which in turn controls the lateral transistor´s current gain. Experimental data on a lateral p-n-p transistor will be given. With this control electrode, high current gain can be obtained without excessively reducing the base width of the lateral transistor. Current gain of a stable single p-n-p transistor as high as fifty has been obtained. Various factors which affect the lateral transistor action such as the physical spacing, surface recombination and collector depletion layer modulation will be discussed. The observed effects can be explained by the surface recombination generation mechanism and the effective surface base width. Relationships between the change of surface potential over the base region and the transistor current gain will be discussed. Comparison of the lateral transistor with and without the control electrode will be discussed also.