Complementary modulation-doped field-effect transistors
AssigneeNorthern Telecom Limited
InventorStephen Joseph Kovacic
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Abstract
Complementary Modulation-Doped Field-Effect Transistors (CMODFETs) using a heterostructure based Silicon and Germanium alloys are described. The design of the Si/Si.sub.1-x Ge.sub.x -based CMODFET is also presented and shown to enable both n-channel or p-channel transport between source and drain implantation regions of the carriers with mobilities enhanced by 1) low ionized dopant scattering phenomena and 2) discretization of the free carrier energy due to quantum confinement.
Claims20
A semiconductor heterostructure enabling the fabrication of both n-channel and p-channel modulation doped field effect transistors (MODFET) comprising in sequence:
- a first undoped or lightly p-doped layer of silicon or silicon alloy;
- a second heavily n-doped layer of silicon or silicon alloy;
- a third silicon alloy layer;
- a fourth heavily n-doped layer of silicon or silicon alloy;
- a fifth undoped or lightly p-doped layer of silicon or silicon alloy;
- wherein a conduction band well exists in the third layer and a valence band hetero-offset exists between the third layer and each of the second and fourth layers.
A semiconductor heterostructure enabling the fabrication of both n-channel and p-channel modulation doped field effect transistors (MODFET) comprising
- a) a sequence of layers comprising:
- a first undoped or lightly p-doped layer of silicon or silicon alloy;
- a second heavily n-doped layer of silicon or silicon alloy;
- a third silicon alloy layer;
- b) for each MODFET to be fabricated
- a heavily doped source region and a heavily doped drain region extending through at least a portion of the third layer, the source region and the drain region being of the same conductivity type;
- a drain electrode on the drain region and a source electrode on the source region;
- a first heavily n-doped mesa structure layer of silicon or silicon alloy between the drain electrode and the source electrode;
- a second undoped or lightly p-doped mesa structure layer of silicon or silicon alloy overlying the first mesa structure layer;
- and
- a gate electrode on the second mesa structure layer;
- wherein a conduction band well exists in the third layer and a valence band hetero-offset exists between the third layer and each of the second layer and the first mesa structure layer.
Dependencies are inferred from the claim text.