JFET devices with increased barrier height and methods of making same
Devices and methods for providing JFET transistors with improved operating characteristics are provided. Specifically, one or more embodiments of the present invention relate to JFET transistors with a higher diode turn-on voltage. For example, one or more embodiments include a JFET with a doped silicon-carbide gate, while other embodiments include a JFET with a metal gate. One or more embodiments also relate to systems and devices in which the improved JFET may be employed, as well as methods of manufacturing the improved JFET.
1. A memory device, comprising:
a semiconductor substrate comprising a source region and a drain region;
a charge storage device coupled to either the source region or the drain region; and
a gate stack formed directly on the semiconductor substrate between the source region and the drain region, the gate stack comprising one or more layers of metal, wherein the gate stack comprises a semiconductor material formed directly on the semiconductor substrate and at least one of the one or more layers of metal formed directly on the semiconductor material;
wherein the gate stack is configured to form a Schottky barrier, wherein the Schottky barrier is formed between the semiconductor material and the metal.
2. The memory device of claim 1 , wherein the semiconductor material comprises a p-type silicon carbide, and the metal comprises a metal or metal silicide with a work function lower than approximately 4.5 electron volts.
3. A memory device comprising:
a charge storage device; and
a transistor coupled to the charge storage device and comprising:
a semiconductor substrate comprising a source region and a drain region;
a channel region comprising a first semiconductor material having a first bandgap formed in the semiconductor substrate between the source region and the drain region and configured to pass current between the source region and the drain region; and
a gate comprising a second semiconductor material having a second bandgap formed directly on a top surface of the semiconductor substrate over the channel region;
wherein the difference between the first bandgap and the second bandgap produce a barrier height greater than 0.5 electron volts.
4. The memory device of claim 3 , wherein the gate further comprises a contact interface formed on the second semiconductor material, the contact interface comprising a third semiconductor material having a third bandgap.
5. The memory device of claim 4 , wherein the first semiconductor material is silicon, the second semiconductor material is silicon carbide, and the third semiconductor material is silicon germanium carbide.
6. The memory device of claim 3 , wherein the barrier height between the channel region and the gate is approximately 2.0 electron volts.