Heterojunction bipolar transistors with intrinsic interlayers
View Patent ↗Heterojunction bipolar transistors are provided that include at least one contact (e.g., collector, emitter, and/or base) formed by a heterojunction between a crystalline semiconductor material and a doped non-crystalline semiconductor material layer. An interfacial intrinsic non-crystalline semiconductor material layer is present at the heterojunction between the crystalline semiconductor material and the doped non-crystalline semiconductor material layer. The presence of the interfacial intrinsic non-crystalline semiconductor material layer improves the surface passivation of the crystalline semiconductor material by reducing the interface defect density at the heterojunction.
1. A heterojunction bipolar transistor comprising:
a crystalline semiconductor material; and
at least one contact in direct physical contact with a surface portion of the crystalline semiconductor material, wherein said at least one contact comprises an interfacial intrinsic non-crystalline semiconductor material in direct contact with the surface portion of the crystalline semiconductor material and a doped non-crystalline semiconductor material located on a surface of the interfacial intrinsic non-crystalline semiconductor material, wherein said interfacial intrinsic non-crystalline semiconductor material is hydrogenated, and said doped non-crystalline semiconductor material is non-hydrogenated.
2. The heterojunction bipolar transistor of claim 1 , further comprising another doped non-crystalline semiconductor material located on a surface of said doped non-crystalline semiconductor material, wherein said another doped non-crystalline semiconductor material has a lower band gap than the doped non-crystalline semiconductor material.
3. The heterojunction bipolar transistor of claim 1 , wherein said doped non-crystalline semiconductor material comprises a multilayered stack of alternating wide band gap semiconductor materials and narrow band gap semiconductor materials.
4. The heterojunction bipolar transistor of claim 1 , further comprising an electrode material portion atop the doped non-crystalline semiconductor material.
5. The heterojunction bipolar transistor of claim 4 , wherein said electrode material portion has outermost edges that are vertical coincide to outermost vertical edges of both said interfacial intrinsic non-crystalline semiconductor material and said doped non-crystalline semiconductor material.
6. The heterojunction bipolar transistor of claim 4 , wherein said electrode material portion has outermost edges that are not vertical coincide to outermost vertical edges of both said interfacial intrinsic non-crystalline semiconductor material and said doped non-crystalline semiconductor material.
7. The heterojunction bipolar transistor of claim 1 , further comprising passivation material layer portions located on other surface portions of the crystalline semiconductor material in which said at least one contact is not in direct physical contact with the surface portion of the crystalline semiconductor material of the first conductivity type.
8. The heterojunction bipolar transistor of claim 1 , wherein said at least one contact is selected from a collector contact, an emitter contact, a base contact, and any combination thereof.
9. The heterojunction bipolar transistor of claim 8 , wherein said collector contact and said emitter contact are located on a first side of the crystalline semiconductor material and said base contact is located on a second side of the crystalline semiconductor material which is opposite said first side.
10. The heterojunction bipolar transistor of claim 9 , wherein said doped non-crystalline semiconductor material of said collector contact and said emitter contact is of a conductivity type that is opposite to a conductivity type of said crystalline semiconductor material.
11. The heterojunction bipolar transistor of claim 10 , wherein said doped non-crystalline semiconductor material of said base contact is of a conductivity type that is the same as a conductivity type of said crystalline semiconductor material, and wherein the dopant concentration of said doped non-crystalline semiconductor material of said base contact is greater than the dopant concentration of the crystalline semiconductor material.
12. The heterojunction bipolar transistor of claim 8 , wherein said collector contact, said emitter contact, and said base contact are each located on a first side of the crystalline semiconductor material.
13. The heterojunction bipolar transistor of claim 12 , wherein said doped non-crystalline semiconductor material of said collector contact and said emitter contact is of a conductivity type that is opposite to a conductivity type of said crystalline semiconductor material.
14. The heterojunction bipolar transistor of claim 13 , wherein said doped non-crystalline semiconductor material of said base contact is of a conductivity type that is the same as a conductivity type of said crystalline semiconductor material, and wherein the dopant concentration of said doped non-crystalline semiconductor material of said base contact is greater than the dopant concentration of the crystalline semiconductor material.
15. The heterojunction transistor of claim 1 , wherein said crystalline semiconductor material is an uppermost layer of a semiconductor-on-insulator substrate.