| 摘要 |
PURPOSE:To make a junction area between base and collector electrodes small by etching the third and fourth layers in the form of an inverted taper to make eaves and by forming selectively the fifth layer having the second conductivity type below these eaves. CONSTITUTION:An n-type InP layer 2, a p-type GaAsP layer 3, the n-type InP layer 4, and an n-type InGaAsP layer 5 perform an epitaxial growth one after another on a semi-insulation InP substrate 1. And an insulating film 11 is formed and then layers 5 and 4 are selectively etched with the insulating film 11 as a mask and are removed partially in the form of an inverted taper and eaves 14 are formed. As an interval between the n-type layer 4 and a base electrode 9 is determined by the eaves 14, it comes to extremely short one, that is, only 0.2-0.3mum. While the p-type InGaAsP layer 3 and the base electrode 9 are etched with the same mask consisting of insulating film 7, the interval between an edge of the p-type InGaAsP layer 3 and the base electrode 9 is almost zero. This configuration makes an junction area between base and collector electrodes drastically small.
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