| 摘要 |
PURPOSE:To obtain a device structure suitable to form a collector layer into a thin film and effective for reducing the sheet resistivity of a base by a method wherein the base layer of a two-dimensional electron gas heterojunction bipolar transistor (2DEG-HBT) is formed in a three-layer structure with two-dimensional electron gas (2DEG). CONSTITUTION:For example, a P<+> GaAs layer 41 (collector layer) containing Be of 1X10<19>cm<-3>, an undoped GaAs collector layer 42, an N-type AlxGa1-xAs (x-0.3) layer 43' containing Si of 3X10<18>cm<-3>, an undoped GaAs layer 42, an N-type AlGaAs layer 43 containing Si of 3X10<18>cm<-3>, a P-type AlGaAs layer 45 containing Be of 1X19<19>cm<-3> and a P-type GaAs layer 45' are respectively formed on a semi-insulative GaAs substrate 40 in 4000 Angstrom , 700 Angstrom , 60 Angstrom , 100 Angstrom , 200 Angstrom , 1500 Angstrom and 2000 Angstrom using an MBE (molecular beam epitaxy) method. Then, an emitter region, a base region and an interelement isolation are formed by mesa etching and a metal emitter electrode 25, a metal base electrode 24 and a metal collector electrode 26 are each formed.
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