1. A high electron mobility transistor (HEMT) comprising:
a channel layer being composed of a II-VI compound semiconductor zinc oxide (ZnO);
a gate contact disposed in proximity to, but not in contact with, said channel layer; and
a gate insulating layer disposed between and in contact with said gate contact and said channel layer and composed of at least one of a Group-III nitride compound semiconductor and a magnesium zinc oxide (MgZnO) quantum well structure, said gate insulating layer having side walls, said gate contact positioned between the sidewalls of said gate insulating layer so that sides of said gate contact face the side walls of said gate insulating layer.
2. A HEMT according to claim 1 wherein said gate insulating layer is composed of at least one of an epitaxially grown Group-III nitride compound semiconductor and a MgZnO quantum well structure.
3. A HEMT according to claim 2 wherein said channel layer is composed of an epitaxially grown Group-II-VI zinc oxide compound semiconductor.
4. A HEMT according to claim 1 wherein said gate insulating layer is composed of a Group-III compound semiconductor expressed by a chemical formula AlxGa1\u2212xN (0.3<x\u22661) or MgxZn1\u2212xO (0.1<x<0.4).
5. A HEMT according to claim 1 wherein said channel layer is formed on a substrate comprising at least one of zinc oxide (ZnO), silicon carbide (SiC), sapphire (Al2O3), and silicon (Si) and has a bulk resistivity higher than 105 ohm-centimeter (\u03a9-cm).
6. A HEMT according to claim 1 wherein the thickness of said gate insulating layer ranges from 0.30 nanometer (nm) to 50 nm.
7. A HEMT according to claim 1 wherein said HEMT employs piezoelectric doping created by strain due to lattice mismatch between the channel layer and the gate insulating layer that produces a two-dimensional electron gas (2DEG) near an interface between the channel layer and the gate insulating layer to avoid usage of a conventional doping method.
8. A HEMT according to claim 1 wherein said gate contact is selected from the group consisting of titanium (Ti), platinum (Pt), silver (Ag), gold (Au), chromium (Cr), alloys of titanium(Ti) and tungsten (W), and platinum silicide (PtSi).
9. A HEMT according to claim 1 wherein source and drain contacts to said channel layer comprise an alloy of titanium (Ti), silicon (Si), aluminum (Al) and nickel (Ni).
10. A HEMT according to claim 1 and further comprising a passivation layer on said gate contact and said source and drain contacts to said channel layer.
11. A HEMT according to claim 1 wherein an area of said gate contact with said gate insulating layer is decreased due to the presence of said sidewalls.
12. A HEMT according to claim 1 wherein the channel layer is composed of ZnO and is grown by metal organic chemical vapor deposition (MOCVD).
13. A HEMT according to claim 1 wherein gate insulating layer is grown by metal organic chemical vapor deposition (MOCVD) and sequentially laminated on said channel layer, the HEMT further comprising:
a substrate composed of ZnO, the channel layer laminated onto the substrate.
14. A HEMT according to claim 13 wherein the substrate is a c-surface substrate.
15. A method comprising the steps of:
defining a channel layer composed of a II-VI compound semiconductor zinc oxide (ZnO);
forming a gate insulating layer in contact with said channel layer and composed of at least one of a Group-III nitride compound semiconductor and a magnesium zinc oxide (MgZnO) quantum well structure, said gate insulating layer formed with side walls; and
forming a gate contact disposed on and in contact with said gate insulating layer and positioned between said side walls, said gate contact formed to have sides facing said side walls of said gate insulating layer, said gate contact formed in proximity to, but not in contact with, said channel layer.
16. A method according to claim 15 wherein the gate insulating layer is formed by metal organic chemical vapor deposition (MOCVD).
17. A method according to claim 15 wherein the channel layer is formed on a c-surface ZnO substrate.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An inclination sensor to be mounted to a target device subjected to inclination detection, the sensor comprising:
a case provided with a vacant space; and a rolling member movably accommodated in the vacant space; the inclination sensor being configured to detect an inclination of the target device based on a positional change of the rolling member within the vacant space due to a change in gravitational direction as the target device is caused to incline, the sensor further comprising:
a substrate mounted to a rear surface of the case, the rear surface being parallel to a rolling plane along which the rolling member is movable, the substrate including a first surface that faces the vacant space and is provided with a pair of light receiving elements spaced from each other and a light emitting element for emitting light to be received by the light receiving elements;
wherein the vacant space of the case is configured to cause the rolling member to be brought to a pair of light shielding positions and a neutral position due to the change in gravitational direction, the light shielding positions corresponding in location to the light receiving elements respectively, and the neutral position corresponding in location to the light emitting element and being located out of the light receiving elements;
wherein the substrate includes a second surface opposite to the first surface provided with the light receiving elements and the light emitting element, the second surface being provided with a plurality of terminals extending in parallel to the rolling plane for surface-mounting;
wherein a reflection surface is provided for reflecting light emitted from the light emitting element, the reflection surface being arranged at a location opposite from the substrate across the vacant space of the case; and
wherein the reflection surface of the case is made of a thin film.
2. The inclination sensor according to claim 1, wherein the rolling member has a columnar shape having a central axis extending perpendicularly to the plane along which the rolling member moves.
3. The inclination sensor according to claim 1, further comprising a wiring pattern formed on the first surface of the substrate for bonding the light emitting element and the light receiving elements, the wiring pattern extending to the second surface of the substrate and connected to the terminals for surface mounting.
4. A combination of an inclination sensor and a circuit board, the circuit board having a mount surface on which the inclination sensor is attached for inclination detection of the circuit board, the inclination sensor comprising: a case provided with a vacant space; and a rolling member movably accommodated in the vacant space; the inclination sensor being configured to detect an inclination of the circuit board based on a positional change of the rolling member within the vacant space due to a change in gravitational direction as the target device is caused to incline, the sensor further comprising:
a substrate mounted to a rear surface of the case, the substrate including a first surface that faces the vacant space and is provided with a pair of light receiving elements spaced from each other and a light emitting element for emitting light to be received by the light receiving elements;
wherein the vacant space of the case is configured to cause the rolling member to be brought to a pair of light shielding positions and a neutral position due to the change in gravitational direction, the light shielding positions corresponding in location to the light receiving elements respectively, and the neutral position corresponding in location to the light emitting element and being located out of the light receiving elements;
wherein the substrate includes a second surface opposite to the first surface provided with the light receiving elements and the light emitting element;
wherein the mount surface of the circuit board is parallel to the rolling plane along which the rolling member is movable; and
wherein the second surface of the substrate is provided with a plurality of terminals extending in parallel to the rolling surface for surface-mounting to the mount surface of the circuit board.
5. An inclination sensor to be mounted to a target device subjected to inclination detection, the sensor comprising:
a case provided with a vacant space; and a rolling member movably accommodated in the vacant space; the inclination sensor being configured to detect an inclination of the target device based on a positional change of the rolling member within the vacant space due to a change in gravitational direction as the target device is caused to incline, the sensor further comprising:
a substrate mounted to a rear surface of the case, the rear surface being parallel to a rolling plane along which the rolling member is movable, the substrate including a first surface that faces the vacant space and is provided with a pair of light receiving elements spaced from each other and a light emitting element for emitting light to be received by the light receiving elements;
wherein the vacant space of the case is configured to cause the rolling member to be brought to a pair of light shielding positions and a neutral position due to the change in gravitational direction, the light shielding positions corresponding in location to the light receiving elements respectively, and the neutral position corresponding in location to the light emitting element and being located out of the light receiving elements;
wherein the substrate includes a second surface opposite to the first surface provided with the light receiving elements and the light emitting element, the second surface being provided with a plurality of terminals extending in parallel to the rolling plane for surface-mounting;
wherein the inclination sensor further comprises a cover bonded to the case and having a reflection film for reflecting light emitted from the light emitting element toward the light receiving elements.
6. An inclination sensor to be mounted to a target device subjected to inclination detection, the sensor comprising:
a case provided with a vacant space; and a rolling member movably accommodated in the vacant space; the inclination sensor being configured to detect an inclination of the target device based on a positional change of the rolling member within the vacant space due to a change in gravitational direction as the target device is caused to incline, the sensor further comprising:
a substrate mounted to a rear surface of the case, the rear surface being parallel to a rolling plane along which the rolling member is movable, the substrate including a first surface that faces the vacant space and is provided with a pair of light receiving elements spaced from each other and a light emitting element for emitting light to be received by the light receiving elements;
wherein the vacant space of the case is configured to cause the rolling member to be brought to a pair of light shielding positions and a neutral position due to the change in gravitational direction, the light shielding positions corresponding in location to the light receiving elements respectively, and the neutral position corresponding in location to the light emitting element and being located out of the light receiving elements;
wherein the substrate includes a second surface opposite to the first surface provided with the light receiving elements and the light emitting element, the second surface being provided with a plurality of terminals extending in parallel to the rolling plane for surface-mounting;
wherein the inclination sensor further comprises a wiring pattern formed on the first surface of the substrate for bonding the light emitting element and the light receiving elements, the wiring pattern extending to the second surface of the substrate and connected to the terminals for surface mounting.