Gallium arsenide/aluminum gallium arsenide photocell including environmentally sealed ohmic contact grid interface and method of fabricating the cell

A semiconductor structure, comprising:

• a first layer of an environmentally sensitive, semiconductor material;
• a second layer of an environmentally insensitive, electrically conductive material which is formed over and ohmically communicates with a portion of the first layer;
• a third layer of an environmentally insensitive, electrically insulative material which is formed over the first layer such that the second layer sealingly extends through the third layer;
• and
• an ohmic contact which sealingly adheres to the second layer and a portion of the third layer which is contiguous with the second layer.

A method of fabricating a photosensitive cell, comprising the steps of:

• (a) forming a photosensitive layer structure;
• (b) forming a passivation layer of an environmentally sensitive material over the photosensitive layer structure;
• (c) forming a cap layer of an environmentally insensitive, electrically conductive material over the passivation layer;
• (d) removing a first portion of the cap layer to expose an underlying portion of the passivation layer such that a second portion of the cap layer remains over the passivation layer;
• (e) forming an antireflection coating of an environmentally insensitive, electrically insulative material over said exposed portion of the passivation layer such that said second portion of the cap layer extends through the coating and, with the coating and second portion of the cap layer, seals the passivation layer;
• and
• (f) forming an ohmic contact of an electrically conductive material over said second portion of the cap layer, comprising the substeps of:
• (g) forming a mask over said antireflection coating such that a lateral gap is provided between the mask and said second portion of the cap layer;
• (h) forming an ohmic contact material over the mask, over the portion of the antireflection coating in said gap, and over said second portion of the cap layer;
• and
• (i) lifting off the mask and said contact material overlying the mask.