Bell Telephone Laboratories

At&t Bell Laboratories

Richard W Dixon

Louis A Koszi

Bertram Schwartz

Maria A Argiriadi

Jonathan P Belk

Carolyn A Cuff

Richard C Miller

Shankar Kumar

Yan Chen

Chengbin Wu

Paul R Hinton

Hua Ying

William Baxter Joyce

Franklin R Nash

Joseph F Svacek, Iii

Semiconductor light emitting devices, lasers and LEDs, are described in which the current flow channel is narrower near the top surface of the device and wider at its bottom near the active region. Also, described are several attenuation masks for fabricating the channels of these devices by particle bombardment.

Method of forming current confinement channels in semiconductor devices

Current confinement in semiconductor light emitting devices

This invention is a semiconductor junction laser which operates in a transverse mode, other than the fundamental mode, parallel to the p-n junction. An undesired transverse mode parallel to the p-n junction may be suppressed by introducing a lossy region within the laser where this mode has at least one of its maxima. The zero order transverse mode parallel to the p-n junction may be suppressed in a double heterostructure stripe geometry laser by introducing an optically or electrically lossy region in the current flow path of the laser where the zero order mode has its maximum. This double heterostructure stripe geometry laser operates linearly with respect to current in the first order transverse mode parallel to the p-n junction.

Semiconductor lasers with stable higher-order modes parallel to the

The apparent differential output power or quantum efficiency of a semiconductor laser, such as a double heterostructure laser diode, is reduced by means of a circuit which shunts the laser and includes a threshold device. The I-V characteristic of the shunt circuit intersects that of the laser at V.sub.x such that at voltages below V.sub.x the current through the laser exceeds that through the shunt, and conversely above V.sub.x. Specific embodiments of the shunt circuit include a resistor in series with either a zener diode or one or more forward-biased conventional diodes.

Circuit for controlling the differential output power of a semiconductor

Current confinement in semiconductor devices by means of buried high resistivity zones is described. For example, in a stripe geometry, semiconductor, junction laser the laterally separate, high resistivity zones, which confine current flow in a narrow channel between the upper and lower electrical contacts, are buried below the upper contact. This configuration permits current to flow from the upper contact into the body of the semiconductor over greatly increased area before it enters the channel. The current density at the interface between the upper contact and the semiconductor body is thereby reduced, making the quality of that interface less important. Several processes which employ proton bombardment for fabricating the laser are also described: (1) in one the normal sequence of Zn diffusion and proton bombardment is reversed, and (2) in the other the profiles of Zn doping and proton damage are suitably tailored.

Current confinement in semiconductor lasers

Described is a technique for generating directly certain derivatives of device parameters by measuring the device response to ac modulation under conditions of constant modulation index. In particular, the technique as it applies to measuring directly idF/di and i.sup.2 d.sup.2 F/di.sup.2 for AlGaAs DH p-n junction lasers is described for two cases: where the generalized function F equals either voltage V across the laser or the light intensity output L of the laser, and i equals current through the laser. For p-n junction lasers this technique permits measurement of the series resistance R.sub.s, lasing current threshold i.sub.th and the exponential factor .beta. = q/nkT.

Constant modulation index technique for measuring the derivatives of

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Bernardsville, NJ, United States of America

Richard W Dixon