Abstract: A bipolar-type semiconductor device, such as a bipolar transistor, has a heavily doped emitter region, a lightly doped emitter region, a base region, a collector region and a passivation layer or layers on said regions. The passivation layer formed on a surface end of a PN junction between the collector region and the base region is a polycrystalline silicon containing oxygen atoms in a range between 14 and 35 atomic percents. The other passivation layer formed on a surface end of the other PN junction between the base region and the lightly doped emitter region is made of silicon-dioxide, which covers also a surface end of lightly doped and heavily doped (LH) junction between two emitter regions.

Abstract: A Schottky barrier is formed between a semiconductor substrate and a metal contact and stabilized by a polycrystalline silicon layer containing oxygen in the range between 2 and 45 atomic percent and surrounding a peripheral portion of the metal contact to improve the breakdown voltage characteristics of the device. The invention is applicable to Schottky barrier type diodes, bipolar transistors, field effect transistors and so on.

Abstract: A semiconductor device such as a transistor, has a heavily doped emitter, a lightly doped emitter, a base, a collector, an insulating layer covering the lightly doped emitter and a conductive layer extending on the insulating layer covering an L - H junction which is formed by the lightly doped and heavily doped emitters.The L-H junction and the insulating layer is located at the distance from an emitter-base junction within the diffusion length of minority carriers in the lightly doped emitter.The above insulating layer is formed before the forming of the heavily doped emitter so that the surface recombination velocity in the emitter is reduced.

Abstract: A transistor circuit comprising a bipolar transistor with high input impedance is disclosed. The transistor has low emitter-base conductance, and especially has a low conductance component caused by the recombination of minority carriers in an emitter. The emitter capacitance caused by stored minority carriers is low because of the low conductance component. These enable emitter-grounded operation at high current gain and high frequency.