US 2002/0177250 A1 · Current confinement structure for vertical cavity surface emitting laser

Abstract

A vertical cavity surface emitting laser (VCSEL) structure and fabrication method therefor are described in which a subsurface air, gas, or vacuum current confinement method is used to restrict the area of electrical flow in the active region. Using vertical hollow shafts to access a subsurface current confinement layer, a selective lateral etching process is used to form a plurality of subsurface cavities in the current confinement layer, the lateral etching process continuing until the subsurface cavities laterally merge to form a single subsurface circumferential cavity that surrounds a desired current confinement zone. Because the subsurface circumferential cavity is filled with air, gas, or vacuum, the stresses associated with oxidation-based current confinement methods are avoided. Additionally, because the confinement is achieved by subsurface cavity structures, overall mechanical strength of the current-confining region is maintained.

Claims30

Dependent claims

In a vertical cavity surface emitting laser (VCSEL) comprising vertically stacked material layers including a first material layer positioned above a second material layer, an intermediate region being disposed therebetween, electrical current flowing between the first material layer and the second material layer through the intermediate region during operation of the VCSEL, a current confinement structure for laterally restricting the flow of electrical current passing through the intermediate region, comprising:

a central column of semiconductor material vertically extending between the first and second material layers;
a subsurface cavity laterally circumscribing said central column of semiconductor material and vertically extending between the first and second material layers, said subsurface cavity being filled with a non-solid material;
and
an outer support element laterally surrounding said subsurface cavity, said outer support element comprising a non-conducting material, said outer support element mechanically supporting said first and second material layers in conjunction with said central column of semiconductor material, the electrical current being laterally confined to said central column while passing from the first layer to the second layer.

1 more element

A method of fabricating a current confinement structure into a partially-constructed VCSEL, said partially-constructed VCSEL having an active layer disposed between an upper set of material layers thereabove and a lower set of material layers therebelow, said partially-constructed VCSEL further comprising a current confinement layer positioned below the upper set of material layers and immediately above the active layer, comprising:

forming at least three hollow vertical shafts extending downward from a top surface of the upper set of material layers to at least a bottom of the current confinement layer, the vertical shafts being laterally positioned outside a desired current confinement zone;
and
etching with a selective etchant that laterally etches the current confinement layer substantially faster than it etches any of the upper material layers and substantially faster than it etches the active layer, the current confinement layer thereby being etched away outwardly from an axis of each vertical shaft so as to form a subsurface void around each hollow vertical shaft at the current confinement layer, said etching continuing until the subsurface cavities merge together to form a single subsurface circumferential cavity around the desired current confinement zone.

Dependencies are inferred from the claim text.

Current confinement structure for vertical cavity surface emitting laser

Life of this patent

Current confinement structure for vertical cavity surface emitting laser

Life of this patent

Abstract

Claims30