Hughes Aircraft Company

Hughes Electronics Corporation

Takyiu Liu

Chanh N Nguyen

Mehran Matloubian

Mark Lui

Linda M Jelloian

Epitaxial growth of a chirped superlattice with constant dopings is achieved with minimal growth interruption time. This is done by doping only one of the two compositions during growth of its layer. For example, in the growth of a plurality of alternating layers of InP and GaInAs to form the superlattice, either the InP layers are doped with an n-type dopant, such as silicon, or the GaInAs layers are doped with a p-type dopant, such as beryllium. Alternatively, InP can equally be doped p-type (with beryllium) and GaInAs can be doped n-type (with silicon). In either case, the doping scheme described herein is easily done during molecular beam epitaxial growth by opening and closing the shutter of the dopant (silicon or beryllium) source cell at the appropriate times. To the electrical carriers, the doping superlattice scheme of the present invention presents a uniform doping without any need to change the doping cell temperature. This in turn allows improved controllability and minimal interface contamination.

Effective constant doping in a graded compositional alloy

An epitaxial structure and method of manufacture for a field-effect transistor capable of high-speed low-noise microwave, submillimeterwave and millimeterwave applications. Preferably, the epitaxial structure includes a donor layer and/or buffer layer made from a semiconductor material having the formula AlP.sub.0.39+y Sb.sub.0.61-y.

Method of making high-speed, low-noise millimeterwave HEMT and

An epitaxial structure and method of manufacture for a field-effect transistor capable of low-noise and power applications. Preferably, the epitaxial structure includes an N-type barrier layer comprising a wide-gap semiconductor material having the formula Al.sub.1-y Ga.sub.y P.sub.0.71+z Sb.sub.0.29-z.

Low-noise and power ALGaPSb/GaInAs HEMTs and pseudomorpohic HEMTs on

An epitaxial structure and method of manufacture for a single heterojunction bipolar transistor capable of being utilized in high-speed and high-power applications. Preferably, the epitaxial structure comprises an N-type collector made from InP, a P-type base made from InP, and an N-type emitter made from a semiconductor material of approximately 39 mole percent AlP and approximately 61 mole percent Sb.

AlPSb/InP single heterojunction bipolar transistor on InP substrate for

Method of making an AlPSb/InP single heterojunction bipolar transistor

A double heterojunction bipolar transistor (DHBT) is provided with a parabolic grade in bandgap at the base-collector junction. The parabolic grade in bandgap is close to parabolic in composition. The parabolic grade in bandgap is achieved by employing a chirped superlattice to mimic the parabolically varying alloy composition. Each period of the superlattice consists of one low-bandgap layer and one high-bandgap layer. The average composition in each period is determined by the relative thicknesses of these two layers. By varying the thickness ratio of these two layers approximately parabolically with (i) the distance from the base for a concave parabola and (ii) the distance from the collector for a convex parabola, the intended parabolic grade is achieved. The exact values may be computed numerically.

Parabolically graded base-collector double heterojunction bipolar

High breakdown voltages for AlInAs layers in InP-based devices, such as a gate layer in an InP HEMT or a collector layer in a heterojunction bipolar transistor, are achieved by growing the AlInAs layer by MBE at a substrate temperature about 70.degree.-125.degree. C. below the temperature at which a 2.times.4 reflective high energy diffraction pattern is observed. This corresponds to a growth temperature range of about 415.degree.-470.degree. C. for a 540.degree. 2.times.4 reconstruction temperature. Preferred growth temperatures within these ranges are 80.degree. C. below the 2.times.4 reconstruction temperature, or about 460.degree. C. Higher breakdown voltages are obtained than when the AlInAs layer is grown at either higher or lower temperatures.

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Newbury Park, CA, United States of America

Takyiu Liu