Modulation doped field effect transistor
AssigneeMotorola, Inc.
InventorsCharles E. Weitzel, Neal Mellen, Kenneth L. Davis, Paige Holm
Life of this patent
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Abstract
A modulation doped field effect transistor (10) is formed to have a drain (28, 12, 11) that is vertically displaced from the source (16, 17) and channel (20, 21) regions. The transistor (10) has the source (16, 17), channel (20, 21) and a portion of the drain (28) arranged laterally so that current (27) flows from the source (16, 17) laterally to the drain (28, 12, 11). A heterojunction layer (18) on the channel region (20, 21) facilitates forming a two dimensional electron gas in the channel (20, 21) region which provides the transistor (10) with a high transconductance.
Claims17
A modulation doped field effect transistor comprising:
- a substrate having a first surface;
- a drift layer of a first conductivity type having a first band gap and a first surface on the first surface of the substrate;
- a first blocking region of a second conductivity type on the second surface of the drift layer wherein the first blocking region is a doped region of the drift layer;
- a first source region of the first conductivity type within the first blocking region;
- a heterojunction layer on the drift layer, the heterojunction layer covering a portion of the first blocking region that is between an edge of the first blocking region and an edge of the source region wherein the heterojunction layer is formed from a material having a band gap that is larger than the first band gap;
- a charge supply region in the heterojunction layer, the charge supply region overlaying the first blocking region and adjacent to the first blocking region wherein the charge supply region has a doping concentration that is higher than a doping concentration within the first blocking region;
- and
- a Schottky gate on the heterojunction layer.
A semiconductor device comprising:
- a source region;
- a channel region laterally displaced from the source region, the channel region having a first band gap;
- a heterojunction layer on the channel region and on the source region, the heterojunction layer having a second band gap that is larger than the first band gap;
- and
- a charge supply region in the heterojunction layer and adjacent to the channel region, the charge supply region having a doping concentration that is higher than a doping concentration of the channel region.
Dependencies are inferred from the claim text.