Rockwell International Corporation

David L Miller

Peter M Asbeck

Mau-Chung Frank Chang

Keh-Chung Wang

A heterostructure complementary transistor switch (HCTS) is fabricated using epitaxial layers on a substrate to form the desired P-N-P-N (or N-P-N-P) complementary structure in III-V compound semiconductor materials. Two HCTS are formed on a single substrate to form a memory cell. A collector and a base on one of the HCTs are connected to a base and a collector, respectively, on the other HCTS to form the memory cell.

Static memory cell using a heterostructure complementary transistor

The crystallographic plane-dependent, amphoteric nature of Si-doped AlGaAs is used to provide a low threshold semiconductor laser. An active layer of AlGaAs is sandwiched between an injection layer and a current confining layer of AlGaAs. The injection layer is doped to be n-type conductivity. The confining layer is amphoterically doped with Si to be n-type in a (100) plane and p-type in a (111)A plane. The resulting p-n junctions, heterostructure, and geometry provide the current and the optical confinement for the semiconductor laser.

Heterostructure semiconductor laser

Silicon doping of GaAs provides n conductivity in {100} planes and p conductivity in {111} A planes. A split level of Si-doped GaAs utilizes this phenomena to provide a bipolar transistor. In one embodiment, the emitter is one level of the layer in the {100} planes, and the collector is another level of the layer in the {100} planes. These n conductivity levels are joined by {111} A planes to form a p conductivity base. The junctions in the layer between the {100} planes and the {111} A planes form an npn transistor.

Lateral bipolar transistor

A method is provided for selectively doping a compound semiconductor such as GaAs in situ by molecular beam epitaxy. The surface of the GaAs is coated with a thin layer of As by exposing it to an arsenic flux within a molecular beam epitaxy chamber. Selected areas of the surface are irradiated with a laser beam or a beam of photons, electrons, or ions in order to desorb As and form a mask of As on the surface. Dopant material such as tin is then deposited over the surface and As mask. The semiconductor is then heated to desorb the As mask while leaving the dopant in the unmasked areas. An epitaxial layer of GaAs is then grown over the surface by molecular beam epitaxy.

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Thousand Oaks, CA, United States of America

David L Miller