Optoelectronic device

An optical receiver including an optoelectronic semiconductor device comprising:

• a first epitaxial layer grown on a semiconductor substrate,
• a second epitaxial layer grown on said first layer, said second epitaxial layer having a higher refractive index than that of the first layer and an optical input/outputs and
• a third epitaxial layer in the form of a ridge structure selectively grown on or over said second layer,
• wherein said first epitaxial layer is of a first conductivity types said third epitaxial layer is of a second conductivity type and a p-n junction is formed in said second epitaxial layer between a region of material of said second conductivity types which is aligned beneath said ridge structure, and adjacent regions of said first conductivity type of said second layer, and having an electrical output/input across said p-n junction.

A method of fabricating an optoelectronic device, the method comprising the steps of:

• (i) growing a first epitaxial layer of a first conductivity type on a semiconductor substrate;
• (ii) growing a second epitaxial layer of said first conductivity type on said first layer;
• (iii) forming a dielectric layer on or over said second layer;
• (iv) derming a pattern in said dielectric layer by selective removal of parts thereof;
• using selective epitaxy to grow a third epitaxial layer on semiconductor exposed by the patterned dielectric, said third epitaxial layer including at least one ridge structure;
• and
• (v) diffusing a dopant of a second conductivity type from said third epitaxial layer into said second layer thereby selectively type-converting regions of said second layer and forming a p-n junction therein without type converting underlying parts of said first epitaxial layer.

A method of fabricating an optoelectronic device, the method comprising the steps of:

• i) growing a planar structure which is all of a first conductivity type and comprises a waveguiding layer and an active layer overlying said waveguiding layer;
• ii) forming an inorganic dielectric layer on said planar;
• iii) patterning said dielectric layer to expose underlying semiconductor;
• iv) using selective epitaxial growth to grow material of a second conductivity type on said exposed semiconductor, the selective epitaxial growth including at least one ridge;
• and
• v) simultaneously with step iv) diffusing dopant from said material of a second conductivity type into the planar to form a predetermined arrangement of p-n junctions therein, including a lateral p-n junction aligned with said ridge.