Lattice mismatched heterojunction structures and devices made therefrom
Semiconductor heterojunction structures comprising lattice mismatched, single-crystalline semiconductor materials and methods of fabricating the heterojunction structures are provided. The heterojunction structures comprise at least one three-layer junction comprising two layers of single-crystalline semiconductor and a current tunneling layer sandwiched between and separating the two layers of single-crystalline semiconductor material. Also provided are devices incorporating the heterojunction structures, methods of making the devices and method of using the devices.
1. A semiconductor heterojunction structure comprising:
a layer of a first single-crystalline semiconductor material;
a layer of a second single-crystalline semiconductor material, the second single-crystalline semiconductor material having a different chemical composition and a different lattice constant than the first single-crystalline semiconductor material; and
a current tunneling layer disposed between and in contact with the upper surface of the layer of the first single-crystalline semiconductor material and the lower surface of the layer of the second single-crystalline semiconductor material, wherein the current tunneling layer comprises an inorganic material, wherein the bandgap of the inorganic material is wider than the bandgaps of the first and second single-crystalline semiconductor materials and further wherein the inorganic material is not a native oxide of the first single-crystalline semiconductor material or a native oxide of the second single-crystalline semiconductor material;
wherein the interfaces between the current tunneling layer and the layers of the first and second single-crystalline semiconductor materials do not have an epitaxial structure.
2. The semiconductor heterojunction structure of claim 1 , wherein the semiconductor materials of the first and second layers of single-crystalline semiconductor material have a lattice constant mismatch of at least 2%.
3. The semiconductor heterojunction structure of claim 1 , wherein the inorganic material is an oxide of a metal element, an oxide of a semiconductor element or an oxide of a metalloid element.
4. The semiconductor heterojunction structure of claim 1 , wherein the inorganic material is aluminum oxide.
5. The semiconductor heterojunction structure of claim 4 , wherein the current tunneling layer has an average thickness of no greater than 5 nm.
6. The semiconductor heterojunction structure of claim 1 , wherein the inorganic material is a nitride of a metal element, a nitride of a semiconductor element or a nitride of a metalloid element.
7. The semiconductor heterojunction structure of claim 1 , wherein the first and second single-crystalline semiconductor materials have a coefficient of thermal expansion mismatch of at least 200%.
8. The semiconductor heterojunction structure of claim 1 , wherein the lower surface of the layer of the first single-crystalline semiconductor material and the upper surface of the layer of the second single-crystalline semiconductor material have an rms roughness of at least 2 nm.
9. The semiconductor heterojunction structure of claim 1 , wherein one of the first and second single-crystalline materials is diamond.
10. The semiconductor heterojunction structure of claim 9 , wherein the inorganic material is aluminum oxide.
11. The semiconductor heterojunction structure of claim 9 , wherein the other of the first and second single-crystalline materials is a different Group IV semiconductor, a Group III-V semiconductor or a Group II-VI semiconductor.
12. The semiconductor heterojunction structure of claim 1 , wherein one of the first and second single-crystalline materials is a Group IV semiconductor and the other of the first and second single-crystalline semiconductor materials is a Group III-V semiconductor or a Group II-VI semiconductor.
13. The semiconductor heterojunction structure of claim 1 , wherein the first single-crystalline semiconductor material is p-type doped and the second single-crystalline semiconductor material is n-type doped; and wherein the structure further comprises a first electrical contact in electrical communication with the layer of the first single-crystalline semiconductor material and a second electrical contact in electrical communication with the layer of the second single-crystalline semiconductor material, such the structure provides a PN diode.
14. The semiconductor heterojunction structure of claim 1 , further comprising a layer of a third single-crystalline semiconductor material disposed on the upper surface of the layer of the second single-crystalline semiconductor material, wherein the layer of the first single-crystalline semiconductor material, the layer of the second single-crystalline semiconductor material and the layer of the third single-crystalline semiconductor material form an npn-type band structure or a pnp-type band structure.
15. The semiconductor heterojunction structure of claim 14 , wherein the first semiconductor material is p-type doped diamond, the second semiconductor material is n-type doped silicon, the third semiconductor material is p-type doped silicon and the inorganic material is aluminum oxide.
16. The semiconductor heterojunction structure of claim 14 , wherein the first semiconductor material is p-type doped diamond, the second semiconductor material is n-type doped germanium, the third semiconductor material is p-type doped silicon and the inorganic material is aluminum oxide.
17. The semiconductor heterojunction structure of claim 14 , wherein the first semiconductor material is n-type doped GaN, the second semiconductor material is p-type doped silicon, the third semiconductor material is n-type doped silicon and the inorganic material is aluminum oxide.
18. The semiconductor heterojunction structure of claim 14 , wherein the first semiconductor material is n-type doped GaN, the second semiconductor material is p-type doped germanium, the third semiconductor material is n-type doped silicon and the inorganic material is aluminum oxide.
19. The semiconductor heterojunction structure of claim 1 , further comprising:
a layer of a third single-crystalline semiconductor material having a different chemical composition and a different lattice constant than the second single-crystalline semiconductor material; and
a second current tunneling layer, disposed between and in contact with the upper surface of the layer of the second single-crystalline semiconductor material and the lower surface of the layer of the third single-crystalline semiconductor material, wherein the second current tunneling layer comprises an inorganic material, wherein the bandgap of the inorganic material of the second current tunneling layer is wider that the bandgaps of the second and third single-crystalline semiconductor materials, and further wherein the inorganic material is not a native oxide of the second single-crystalline semiconductor material or a native oxide of the third single-crystalline semiconductor material;
wherein the interfaces between the second current tunneling layer and the layers of the second and third single-crystalline semiconductor materials do not have an epitaxial structure.
20. The semiconductor heterojunction structure of claim 18 , wherein the layer of the first single-crystalline semiconductor material, the layer of the second single-crystalline semiconductor material and the layer of the third single-crystalline semiconductor material form a pnp-type band structure, an npn-type band structure, a pin-type band structure or a pipi-type band structure or a pin-pin-pin type band structure.
21. The semiconductor heterojunction structure of claim 1 , wherein the current tunneling layer comprises at least two sub-layers, each sub-layer comprising an inorganic material, wherein the bandgaps of the inorganic materials are wider that the bandgaps of the first and second single-crystalline semiconductor materials and further wherein the inorganic materials are not native oxides of the first single-crystalline semiconductor material or native oxides of the second single-crystalline semiconductor material.
22. A heterobipolar transistor comprising:
a collector comprising a layer of a first single-crystalline semiconductor material;
a base comprising a layer of a second single-crystalline semiconductor material, the second single-crystalline semiconductor material having a different chemical composition and a different lattice constant than the first single-crystalline semiconductor material;
a current tunneling layer disposed between and in contact with the upper surface of the layer of the first single-crystalline semiconductor material and the lower surface of the layer of the second single-crystalline semiconductor material, wherein the current tunneling layer comprises an inorganic material, wherein the bandgap of the inorganic material is wider than the bandgaps of the first and second single-crystalline semiconductor materials and further wherein the inorganic material is not a native oxide of the first single-crystalline semiconductor material or a native oxide of the second single-crystalline semiconductor material; and
an emitter comprising a layer of a third single-crystalline semiconductor material.