Quantum tunneling devices and circuits with lattice-mismatched semiconductor structures
View Patent ↗Structures include a tunneling device disposed over first and second lattice-mismatched semiconductor materials. Process embodiments include forming tunneling devices over lattice-mismatched materials.
1. A method for forming a structure, the method comprising:
forming an opening above a region of a substrate comprising a first crystalline semiconductor material, the opening being defined by a dielectric sidewall and an exposed surface of the substrate, the opening having a width, the dielectric sidewall having a height equal or greater than a predetermined height, the predetermined height being between half of the width and twice the width;
forming in the opening a second crystalline semiconductor material lattice-mismatched to the first crystalline semiconductor material, the second crystalline semiconductor material having a thickness at least the predetermined height; and
defining a tunneling device over at least a portion of the second crystalline semiconductor material.
2. The method of claim 1 , wherein the tunneling device is selected from the group consisting of an Esaki diode (tunnel diode), a single-barrier tunnel diode, resonant tunneling diode (RTD), a triple-barrier or multiple-barrier resonant tunneling diode, a resonant interband tunneling diode (RITD), a single-barrier interband-tunneling, diode, a resonant tunneling transistor (RTT), a resonant tunneling field-effect transistor (RTFET), a double electron layer tunnel transistor (DELTT), a quantum-well-based resonant tunneling transistor (QWBRTT), a resonant tunneling bipolar transistor (RTBT or RBT), and a resonant tunneling hot-electron transistor (RHET).
3. The method of claim 1 , wherein the second crystalline material is formed in the opening by selective epitaxy.
4. The method of claim 1 , wherein the opening is formed above a region of a transistor.
5. The method of claim 1 , wherein the second crystalline semiconductor material comprises at least one of a II-VI compound or a III-V compound.
6. The method of claim 1 , wherein a majority of defects arising from the lattice-mismatch of the first and second crystalline semiconductor materials terminate below the height of the opening.
7. The method of claim 1 , wherein the width of the opening is less than the height of the opening.
8. A method of forming a transistor structure, the method comprising:
forming an opening above a surface of a substrate comprising a first crystalline semiconductor material, the opening having a non-crystalline sidewall;
forming a second crystalline semiconductor material in the opening, the second crystalline semiconductor material being lattice-mismatched to the first crystalline semiconductor material, a majority of defects arising from lattice-mismatch between the first and second semiconductor materials terminating within the opening;
forming a tunneling structure over and in contact with at least a portion of the second crystalline semiconductor material; and
forming first, second, and third terminals of a transistor proximate the tunneling structure.
9. The method of claim 8 , wherein forming the first, the second, and the third terminals comprises removing a portion of the non-crystalline sidewall.
10. The method of claim 8 , wherein forming the tunneling structure comprises epitaxially growing multiple layers of semiconductor material that form quantum wells.
11. The method of claim 8 , wherein forming the tunneling structure comprises forming a superlattice.
12. The method of claim 8 , wherein the second crystalline semiconductor material comprises at least one of a II-VI compound or a III-V compound.
13. The method of claim 8 , wherein the opening having the non-crystalline sidewall is formed in a dielectric layer.