Hughes Aircraft Company

Thomas C Hasenberg

Lawrence E Larson

April S Brown

David H Chow

Juan F Lam

William E Stanchina

William J Gignac

A mid-IR laser is provided having novel AlAs/Al.sub.x Ga.sub.1-x Sb or InAs/Al.sub.x Ga.sub.1-x Sb superlattice cladding regions. The arsenide layers of the n-type cladding region are doped n-type, utilizing silicon, and may be used with conventional active region materials, such as InAs.sub.z Sb.sub.1-z and In.sub.w Ga.sub.1-w As.sub.y Sb.sub.1-y. The novel cladding regions can be deposited without the use of Group VI elements, such as Te, which are not preferred source materials for MBE growth. Furthermore, the need for quaternary layers, such as Al.sub.x Ga.sub.1-x As.sub.y Sb.sub.1-y, used in the prior art devices, is eliminated; consequently, the need for precise control of two Group V fluxes (As and Sb) is eliminated.

Superlattice cladding layers for mid-infrared lasers

High speed Group III-Sb materials are n-doped in a molecular beam epitaxy process by forming a superlattice with n-doped strained layers of a Group III-V compound upon Group III-Sb base layers. The base layers have lower conduction band energy levels than the strained layers, and allow doping electrons from the strained layers to flow into the base layers. The base layers preferably comprise Al.sub.x Ga.sub.1-x Sb, while the strained layers preferably comprise a binary or ternary compound such as Al.sub.y Ga.sub.1-y As having a single Group V component, where x and y are each from 0 to 1.0. The strained layers can be n-doped with silicon or tin, which would produce p-type doping if added directly to the base layers.

Method of fabricating n-type antimony-based strained layer superlattice

N-type antimony-based strained layer superlattice

A heterojunction bipolar transistor (HBT) (10,30) includes an indium-gallium-arsenide (InGaAs), indium-phosphide (InP) or aluminum-indium-arsenide (AlInAs) collector layer (14) formed over an indium-phosphide (InP) substrate (12). A base layer (16,32) including gallium (Ga), arsenic (As) and antimony (Sb) is formed over the collector layer (14), and an AlInAs or InP emitter layer (18) is formed over the base layer (16,32). The base layer may be ternary gallium-arsenide-antimonide (GaAsSb) doped with beryllium (Be) (16), or a strained-layer-superlattice (SLS) structure (32) including alternating superlattice (32b,32a) layers of undoped gallium-arsenide (GaAs) and P-doped gallium-antimonide (GaSb). The GaSb superlattice layers (32a) are preferably doped with silicon (Si), which is much less diffusive than Be.

NPN heterojunction bipolar transistor including antimonide base formed

A short-period, strained superlattice structure includes two coupled quantum well layers separated by a barrier layer. The quantum well layers are preferably formed of indium arsenide and are 2 monolayers thick. The barrier layer is preferably formed of gallium arsenide and is 2 to 10 monolayers thick. The quantum well layers have a lattice parameter or constant which is sufficiently different from that of the barrier layer that a permanent strain exists in the surface. The layers are sufficiently thin that they remain in an unrelaxed state, thereby precluding the formation of misfit dislocations. As an alternative, the superlattice structure may include more than two quantum well layers, each adjacent two of which are separated by a barrier layer. As another alternative, a plurality of structures, each including two quantum well layers separated by a barrier laser may be provided, with each structure separated by a gallium arsenide buffer layer on the order of 170 to 204 angstroms thick. Where incorporated into a semiconductor diode layer as an active region, the strained superlattice structure is capable of exhibiting optical bistability.

Coupled quantum well strained superlattice structure and optically

A type II staggered alignment multiple quantum well (MQW) is integrated into a laser cavity to implement an active Q-switched device. The MQW initially absorbs and stores energy to prevent the device from lasing. In response to an applied electric field, the MQW experiences a sudden charged carrier population inversion and emits a strong, short duration pulse having a directionality conincident with that of the beam within the lasing cavity. A generalization of the invention involves optical amplification in which photon energy is first stored in a type II staggered alignment MQW, followed by the simultaneous application of an electric field and an optical beam to the MQW, such that the stored energy is released in a sudden pulse which is amplified with respect to the applied optical beam, and is co-directional with the applied beam.

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Agoura Hills, CA, United States of America

Thomas C Hasenberg