Bipolar transistor and method for producing the same
AssigneeMurata Manufacturing Co., Ltd.
InventorsYasunari Umemoto, Shigeki Koya, Atsushi Kurokawa
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Abstract
A bipolar transistor has a subcollector layer and a stack of collector, base, and emitter layers on the subcollector layer. On the subcollector layer are collector electrodes. On the base layer are base electrodes. The collector layer includes multiple doped layers with graded impurity concentrations, higher on the subcollector layer side and lower on the base layer side. Of these doped layers, the one having the highest impurity concentration is in contact with the subcollector layer and has a sheet resistance less than or equal to about nine times that of the subcollector layer.
Claims20
A bipolar transistor comprising:
- a subcollector layer having first and second subcollector layer surfaces on opposite sides, and collector electrodes on the first subcollector layer surface;
- a base layer having first and second base layer surfaces on opposite sides, and base electrodes on the first base layer surface;
- a collector layer including a plurality of doped layers, and having first and second collector layer surfaces on opposite sides, with the first and second collector layer surfaces in contact with the second base layer surface and the first subcollector layer surface, respectively, the plurality of doped layers including a first doped layer that has a highest impurity concentration thereamong and is on a side of or in contact with the first subcollector layer surface;
- and
- an emitter layer on the first base layer surface,
- wherein the plurality of doped layers excluding the first doped layer has an impurity concentration at least about an order of magnitude smaller than that in the first doped layer.
A bipolar transistor comprising:
- a subcollector layer having first and second subcollector layer surfaces on opposite sides, and collector electrodes on the first subcollector layer surface;
- a base layer having first and second base layer surfaces on opposite sides, and base electrodes on the first base layer surface;
- a collector layer including a plurality of doped layers, and having first and second collector layer surfaces on opposite sides, with the first and second collector layer surfaces in contact with the second base layer surface and the first subcollector layer surface, respectively, the plurality of doped layers including a first doped layer that has a highest impurity concentration thereamong and is on a side of or in contact with the first subcollector layer surface;
- and
- an emitter layer on the first base layer surface,
- wherein the first doped layer has a two-dimensional shape that extends beyond edges of a two-dimensional shape of the other doped layer or layers when viewed in a direction in which the plurality of doped layers are stacked.
Dependencies are inferred from the claim text.