Epitaxially grown p-type diffusion source for photodiode fabrication
AssigneeSensors Unlimited, Inc.
InventorAlan Richard Sugg
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Abstract
A p-i-n photodiode included a heavily dopes epitaxially grown layer of semiconductor. The photodiode is comprised of heterojunctions of epitaxial material grown on an InP semiconductor substrate (12, 14). A heavily doped layer (20) is patterned on top of an InP layer (18) to define the source of p-type diffusion for the definition of the active region (22) of the p-n junction. The epitaxially grown source layer (20) may be comprised of ternary or quaternary III-V semiconductor alloys, typically InxGa1−xAs. The principle can be extended to alloy layers that are not lattice-matched to the InP substrate. The p-type dopant is typically Zn, but may also consist of other commonly used p-type dopants such as Be.
Claims8
A photodiode apparatus on a semiconductor substrate comprising:
- a first layer region (14) located adjacent to said substrate and comprising a layer of indium phosphate doped n-type material at a level of between 1×1017/cm3 and 2×1018/cm3;
- a second layer region (16) consisting of an indium gallium arsenide layer which is nominally lattice-matched to said first layer region (14) and having a thickness of between 0.5 and 5 μm and is not intentionally doped;
- a third layer region (18) consisting of a layer of indium phosphide approximately 1 μm thick and doped at a level of about 4×1016/cm3;
- a fourth layer region (20) comprising a patterned p-type layer of indium gallium arsenide doped p-type with dopant at a level of approximately 2×1019/cm3 and with a thickness of approximately 0.15 μm;
- and,
- a fifth region (22) comprising a dopant diffused region which extends from said third layer region (18) into said second layer region (16).
Dependencies are inferred from the claim text.