Coupled-well structure for transport channel in field effect transistors
First Claim
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1. A modulation-doped field-effect transistor (MODFET), comprising multiple layers of:
- a semi-insulating substrate;
a first p-doped layer grown over said substrate;
a not-intentionally-doped (NID) well grown over said first p-doped layer, said non-intentionally-doped (NID) well having at least two coupled sub-wells sandwiching a barrier layer;
an undoped spacer layer grown over said NID well;
an electron supply layer grown over said spacer layer;
a cap layer grown over said electron supply layer;
a source diffusion through said cap layer to said first p-doped layer to form the source of said MODFET;
a drain diffusion through said cap layer to said first p-doped layer to form the drain of said MODFET; and
a gate deposited over said cap layer between said drain and said source to from the gate of said MODFET.
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Abstract
Two or more coupled sub-wells are inserted in the quantum well region of a MODFET to move the electron/hole gas away from the interface between the spacer layer and the well region. The channel can be constructed with a wire cross-section to confine the electron/hole gas in two dimensions, thereby reducing the scattering and improving the device performance. Structures with supply layer contacts, along with their application are described. Laterally coupled quantum wire MODFETs are also disclosed. The insertion of a coupled-well transport channel is applicable for Si MOSFETs in improving the high frequency performance.
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Citations
27 Claims
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1. A modulation-doped field-effect transistor (MODFET), comprising multiple layers of:
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a semi-insulating substrate;
a first p-doped layer grown over said substrate;
a not-intentionally-doped (NID) well grown over said first p-doped layer, said non-intentionally-doped (NID) well having at least two coupled sub-wells sandwiching a barrier layer;
an undoped spacer layer grown over said NID well;
an electron supply layer grown over said spacer layer;
a cap layer grown over said electron supply layer;
a source diffusion through said cap layer to said first p-doped layer to form the source of said MODFET;
a drain diffusion through said cap layer to said first p-doped layer to form the drain of said MODFET; and
a gate deposited over said cap layer between said drain and said source to from the gate of said MODFET. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification