Abstract: Logic circuits using a heterojunction field effect transistor structure having vertically stacked complementary devices is provided. A P-channel quantum well and an N-channel quantum well are formed near each other under a single gate electrode and separated from each other by a thin layer of barrier material. P-source and P-drain regions couple to the P-channel. N-source and N-drain regions couple to the N-channel. The P-source/drain regions are electrically isolated from the N-source/drain regions so the P-channel and N-channel devices may be interconnected to provide many logic functions.

Abstract: A heterojunction field effect transistor structure having a plurality of vertically stacked field effect devices. Two or more devices having electrically independent source and drain regions are formed such that a single gate electrode controls current flow in each of the devices. Each of the vertically stacked FETs have electrically isolated channel regions which may be controlled by a single gate electrode. Vertically stacked devices provide greater device packing density.

Abstract: A method of fabricating heterojunction structures includes providing a semiconductor substrate and forming a plurality of semiconductor layers thereon. Ohmic and gate contacts are then formed on the plurality of semiconductor layers and portions of at least one of the semiconductor layers disposed between the ohmic and gate contacts are removed. Gate metal is then formed on the gate contacts. Source and drain regions are formed in the semiconductor layers and the formation is self-aligned to the gate metal. Following the formation of the source and drain regions, ohmic metal is formed on the ohmic contacts.

Abstract: A GaAs complementary HFET structure having an anisotype layer formed underneath the P-channel device gate is provided. The anisotype layer is heavily doped N-type and is formed in contact with a semi-insulating AlGaAs barrier of the P-channel FET. A pre-ohmic layer is formed over the anisotype layer and a gate electrode is formed over the pre-ohmic layer. In a first embodiment, the pre-ohmic layer comprises undoped gallium arsenide amd the gate electrode forms a Schottky diode with the pre-ohmic layer. The anisotype layer forms a semiconductor junction with the semi-insulating AlGaAs barrier wherein the semiconductor junction replaces or augments a conventional Schottky junction. In a second embodiment, the pre-ohmic layer comprises heavily doped InGaAs and the gate electrode forms an ohmic contact to the doped InGaAs. The semiconductor junction at the P-channel device gate results in higher built in potential barrier and improved P-channel gate turn on voltage.

Abstract: A complementary (Al,Ga)As/GaAs heterostructure insulated gate field-effect transistor (HIGFET) approach is described in which both the n-channel and p-channel transistors utilize a two-dimensional electron (hole) gas in undoped high mobility channels to form planar, complementary GaAs-based integrated circuits.

Abstract: A low power complementary (Al,Ga)As/GaAs heterostructure insulated gate field-effect transistor (HIGFET) approach is described in which the n-channel transistor utilizes an In.sub.x Ga.sub.1-x As semiconductor gate to reduce threshold voltage (V.sub.t) of the n-channel FET to allow low power circuit operation.

Abstract: A method of modulation doping GaAs, (Al,Ga)As and related compounds with silicon ions during molecular beam epitaxy (MBE) growth.