Hewlett-packard Company

Other

Timothy D Osentowski

Robert M Fletcher

Chihping Kuo

Chih-Ping Kuo

Virginia M Robbins

Kuo-Hsin Huang

Jiann Yu

A light emitting diode (LED) including a light generation region situated on a light-absorbing substrate also includes a thick transparent layer which ensures that an increased amount of light is emitted from the sides of the LED and only a minimum amount of light is absorbed by the substrate. The thickness of the transparent layer is determined as a function of its width and the critical angle at which light is internally reflected within the transparent layer. The thick transparent layer is located either above, below or both above and below the light generation region. The thick transparent layer may be made of materials and with fabrication processes different from the light generation region.

Light-emitting diode with a thick transparent layer

A high band-gap opto-electronic device is formed by epitaxially growing the device section in a lattice-matched (Al.sub.x Ga.sub.1-x).sub.y In.sub.1-y P-GaAs system. The band-gap of the epitaxial layer increases with x. Instead of growing the device section directly on the GaAs substrate, a layer of (Al.sub.x Ga.sub.1-x).sub.y In.sub.1-y P, graded in x and in temperature while maintaining substantially y=0.5, is grown as a transitional layer. The high band-gap device structures include homojunctions, heterojunctions and particularly a separate confinement quantum well heterostructures. Various embodiments of the invention include devices on absorbing substrates and on transparent substrates, and devices incorporating strained-layer superlattices.

Method of making a high band-gap opto-electronic device

A high band-gap opto-electronic device is formed by epitaxially growing the device section in a lattice-matched (Al.sub.x Ga.sub.1-x).sub.y In.sub.1-y P-GaAs system. The band-gap of the epitaxial layer increases with x. Instead of growing the device section directly on the GaAs substrate, a layer of (Al.sub.x Ga.sub.1-x).sub.y In.sub.1-7 P, graded in x and in temperature while maintaining substantially y=0.5, is grown as a transitional layer. The high band-gap device structures include homojunctions, heterojunctions and particularly a separate confinement quantum well heterostructures. Various embodiments of the invention include devices on absorbing substrates and on transparent substrates, and devices incorporating strained-layer superlattices.

High band-gap opto-electronic device

A light-emitting diode has a semiconductor substrate underlying active p-n junction layers of AlGaInP for emitting light. A transparent window layer of semiconductor different from AlGaInP overlies the active layers and has a lower electrical resistivity than the active layers and a bandgap greater than the bandgap of the active layers, for minimizing current crowding from a metal electrical contact over the transparent window layer. The active layers may be epitaxially grown on a temporary GaAs substrate. A layer of lattice mismatched GaP is then grown on the active layers with the GaP having a bandgap greater than the bandgap of the active layers so that it is transparent to light emitted by the LED. The GaAs temporary substrate is then selectively etched away so that the GaP acts as a transparent substrate. A transparent window layer may be epitaxially grown over the active layers on the face previously adjacent to the GaAs substrate.

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San Jose, CA, United States of America

Timothy D Osentowski