Xerox Corporation

Kevin J Beernink

Robert L Thornton

David P Bour

Thomas L Paoli

Ross D Bringans

Jack A Walker

Noble Marshall Johnson

Gregory J Kovacs

G A Connell

David W Treat

Fernando A Ponce

A method for fabricating a multiple layer semiconductor device, such as a laser, using impurity-induced, or vacancy-enhanced, intermixing of semiconductor layers to selectively inactivate quantum well regions in the device.

Semiconductor laser formed by layer intermixing

Methods for defect-free impurity-induced laser disordering (IILD) of AlGaInP and AlGaAs heterostructures. Phosphorus-doped or As-doped films are used in which silicon serves as a diffusion source and silicon nitride acts as a barrier for selective IILD. High-performance, index-guided (AlGa).sub.0.5 In.sub.0.5 P lasers may be fabricated with this technique, analogous to those made in the AlGaAs material system. The deposition of the diffusion source films preferably is carried out in a low pressure reactor. Also disclosed is a scheme for reducing or eliminating phosphorus overpressure during silicon diffusion into III-V semiconducting material by adding a pre-diffusion anneal step. Defects produced during intermixing are also reduced using a GaInP or GaInP/GaAs cap.

Thermally processed, phosphorus- or arsenic-containing semiconductor

This invention relates to a laser array which can produce at least two independently addressable laser beams, each of which has fully index-guided buried optical waveguides. Specifically, the array is formed by a two-step impurity disordering process, which simplifies the fabrication of laser arrays and optoelectronic integrated circuits.

Transversely injected multiple wavelength diode laser array formed by

The polarity of the semiconductor layers in an AlGaInP semiconductor laser fabricated by impurity induced layer disordering (IILD) is reversed to allow n-doping. Thus, the cladding and confinement layers between the substrate and the active layer will have p-type conductivity. The upper confinement, cladding, and contact layers can be either n or p-type conductivity with n-diffused regions formed by IILD extending down from the contact layer to the lower cladding layer. The electrodes can include either a substrate electrode or a lateral electrode.

Alternative doping for AlGaInP laser diodes fabricated by

An index-guided semiconductor laser diode made by impurity-induced layer disordering (IILD) of AlInP, GaInP and AlGaInP heterostructures. Several techniques for reducing parasitic leakage current via the n-type IILD regions, are described. These include removing the upper portions of the material outside the laser stripe, which can be accomplished by wet or dry etching of the material in a self-aligned manner. As an alternative, after formation of the waveguide, appropriately doped layers are grown over the disordered and as-grown regions of the structure to contact the active waveguide and simultaneously block parasitic shunt current from the disordered regions. Another method provides shallow inset insulating regions to replace the n-type disordered regions at the vicinity of a cap layer used to reduce a current barrier.

Index guided semiconductor laser diode with reduced shunt leakage

A fabrication process and several structures for an index-guided laser diode formed by IILD or for a multiple wavelength laser array containing stacked semi-conductive active layers with quantum wells. The laser wavelength is varied laterally by effectively inactivating quantum wells which have transition wavelengths longer than that desired in the selected portion of the device. The quantum wells are inactivated by intermixing them with the surrounding high band gap semiconductor layers. To accomplish this intermixing without affecting the active layer in nearby regions, a finite source of impurity inducing or promoting intermixing is located in proximity to the quantum well to be intermixed, and the sample is annealed under conditions which allow for lateral patterning of the impurity-induced intermixing. Alternatively, the body is capped over the quantum well to be inactivated with a material which induces vacancies in semi-conductive material during thermal annealing, thus promoting vacancy-enhanced intermixing of the undesired quantum well. The intermixing can also be brought about by patterned annealing or selective laser heating which produces local annealing, or by use of two different caps. For the index-guided laser diode, the flanking index-guiding regions are formed by IILD from a buried impurity source, in which surface conditions are controlled to promote impurity diffusion to the flanking regions but not to the active stripe region between the flanking regions.

Semiconductor laser or array formed by layer intermixing

A method of fabricating monolithic arrays having closely spaced laser stripes which output laser beams with large, but well-controlled, wavelength separations. The method begins by depositing on a substrate a lower cladding layer and a plurality of stacked active regions with different bandgaps and which are separated by etch stop layers. The stacked active regions are stacked in order of decreasing energy bandgaps as one moves away from the substrate. One or more stacks are then formed by etching one or more active layers using a patterned mask and the etch stop layers such that the topmost active region that remains in each stack has a bandgap which corresponds to the desired laser beam color from that stack. An upper cladding layer is then grown over the exposed surfaces. Beneficially, a lateral confinement region is then created around the stacks (such as by using impurity-induced layer disordering). Finally, a capping layer and metallic contacts are added to each stack, and a common metallic contact is added to the substrate.

Method of fabricating a stacked active region laser array

Monolithic arrays having closely spaced laser stripes which output laser beams with large, but well-controlled, wavelength separations. The monolithic array uses a plurality of stacked active regions which are stacked in the order of decreasing energy bandgaps as one moves away from the substrate. Those active regions are separated by one or more thin etch stop layers. Between the bottom active regions and the substrate is a lower cladding layer, while over the topmost active region of each stack is an upper cladding layer. Beneficially, an electrical connection is made to each stack using a heavily doped capping layer/metallic contact above each stack and a metallic contact on the substrate (which is shared by all stacks). Lateral carrier and optical confinement is achieved using a confinement layer which surrounds each stack. Beneficially, that confinement layer is formed using layer induced disordering.

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Mountain View, CA, United States of America

Kevin J Beernink