Biolar transistor
First Claim
1. A bipolar transistor comprising a SiGe base layer and an emitter layer, wherein a non-doped SiGe layer and a non-doped Si layer are provided between the SiGe base layer and the emitter layer, the non-doped SiGe layer is adjacent to the SiGe base layer, and the non-doped Si layer is adjacent to the non-doped SiGe layer and also is adjacent to the emitter layer.
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Accused Products
Abstract
In a bipolar transistor including a base layer made of SiGe, a non-did SiGe layer and a non-doped Si layer are provided between the base layer and an emitter layer. The composition ratio of Ge in the emitter side of SiGe base layer is decreased with increasing proximity to the emitter side, and the composition ratio of Ge in the non-doped SiGe layer is a smaller than the composition ratio of Ge at the emitter layer-side end of the SiGe base layer. In this manner, restriction is put on the diffusion of boron from the base layer to the emitter side, and the base-emitter junction capacitance CBE reduced. Furthermore, the direct-current gain β can be improved by increasing the composition of Ge at the emitter end of the SiGe base layer to more than or equal to a predetermined value.
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Citations
12 Claims
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1. A bipolar transistor comprising a SiGe base layer and an emitter layer,
wherein a non-doped SiGe layer and a non-doped Si layer are provided between the SiGe base layer and the emitter layer, the non-doped SiGe layer is adjacent to the SiGe base layer, and the non-doped Si layer is adjacent to the non-doped SiGe layer and also is adjacent to the emitter layer.
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4. A bipolar transistor comprising:
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a laminated structure composed of a collector layer, a SiGe base layer, a non-doped SiGe layer, a non-doped Si layer and an n-type emitter layer in that order, wherein the composition ratio of Ge gradually decreases with increasing proximity to the emitter layer side in at least a part of the emitter layer side of the SiGe base layer, and the composition ratio of Ge in the non-doped SiGe layer is smaller than the composition ratio of Ge at the emitter-side end of the SiGe base layer.
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5. A bipolar transistor comprising:
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a laminated structure composed of a collector layer, a SiGe base layer, a non-doped SiGe layer, a non-doped Si layer and an n-type emitter layer in that order, wherein the composition ratio of Ge stepwise decreases with increasing proximity to the emitter layer side in at least a part of the emitter layer side of the SiGe base layer, and the composition ratio of Ge in the non-doped SiGe layer is smaller than the composition ratio of Ge at the emitter layer-side end of the SiGe base layer.
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Specification