Method of making an infrared detector

A method of passivating a junction in a semiconductor device comprising the steps of:

• forming a first semiconductor device layer of a first conductivity type on a substrate;
• forming a second semiconductor device layer of a second conductivity type opposite said first type on said first layer to form a junction therebetween;
• grading the composition of said second layer to vary the bandgap of said second layer between said junction and an upper surface of said second layer;
• etching selectively each of said first layer and said second layer to form a mesa wherein said mesa has an edge wall, said junction having a lateral edge exposed along said wall;
• doping said edge wall to produce a diffused junction in said second layer, wherein said doping maintains the crystalline structure of said second layer;
• and
• forming a passivation layer on said second layer and said edge wall.

A method of fabricating a semiconductor device comprising:

• forming an optically absorbent first semiconductor device layer of a first conductivity type on an optically transparent substrate;
• forming a second semiconductor device layer of a second conductivity type opposite said first type on said first device layer to form a PN junction therebetween;
• etching selectively each of said first layer and said second layer to form a mesa wherein said mesa has an edge wall, and further wherein said junction has a lateral edge exposed along said wall;
• metallizing said wall with a metal selected to form an ohmic contact with said first layer and a Schottky barrier with said second layer so that said Schottky barrier extends upwardly from said PN junction to an upper surface of said second layer;
• forming a passivation layer over said second layer and said metal with an opening in said passivation layer to expose a portion of said upper surface;
• forming a first metal electrode in ohmic contact with said portion of said upper surface;
• and
• forming a second metal electrode in ohmic contact with said substrate.

A method of fabricating a semiconductor device comprising:

• forming an optically absorbent first semiconductor device layer of HgCdTe possessing a first conductivity type on an optically transparent substrate;
• loading said substrate with said first layer formed thereupon into a liquid layer epitaxy furnace;
• epitaxially growing a HgCdTe second semiconductor device layer possessing a second conductivity type opposite said first type upon said first device layer;
• growing said second layer in a tellurium solution until said second layer reaches a preselected thickness, thereby forming a PN junction between said first and second layers;
• grading a composition of cadmium between said junction and an upper surface of said second layer;
• etching selectively each of said first layer and said second layer to form a mesa wherein said mesa has an edge wall, and further wherein said junction has a lateral edge exposed along said wall;
• metallizing said wall with a metal forming an ohmic contact with said first layer an forming a Schottky barrier with said second layer so that said Schottky barrier extends upwardly from said PN junction to an upper surface of said second layer;
• forming a passivation layer over said second layer and said metal with an opening in said passivation layer to expose a portion of said upper surface;
• forming a first metal electrode in ohmic contact with said portion of said upper surface;
• and
• forming a second metal electrode in ohmic contact with said substrate.

A method of fabricating a semiconductor device comprising:

• forming an optically absorbent first semiconductor device layer of a first conductivity type on an optically transparent substrate;
• forming a second semiconductor device layer of a second conductivity type opposite said first type on said first device layer to form a PN junction therebetween;
• grading the composition of said second layer to vary the bandgap of said second layer between said junction and an upper surface of said second layer;
• etching selectively each of said first layer and said second layer to form a mesa wherein said mesa has an edge wall, and further wherein said junction has a lateral edge exposed along said wall;
• metallizing said wall with a metal forming an ohmic contact with said first layer and forming a Schottky barrier with said second layer so that said Schottky barrier extends upwardly from said PN junction to an upper surface of said second layer;
• forming a passivation layer over said second layer and said metal with an opening in said passivation layer to expose a portion of said upper surface;
• forming a first metal electrode in ohmic contact with said portion of said upper surface;
• and
• forming a second metal electrode in ohmic contact with said substrate.

A method for passivating a junction in a semiconductor device comprising the steps of:

• forming a first semiconductor device layer on a substrate;
• forming a second semiconductor device layer to form a junction between said first device layer and said second device layer;
• grading the composition of said second layer to vary the bandgap of said second layer between said junction and an upper surface of said second layer;
• etching selectively each of said first layer and said second layer to form a mesa wherein said means has an edge wall, said junction having a lateral edge exposed along said wall;
• and
• metallizing said wall and passivating said junction.