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True Direct Ohmic Contact to Hydrogenated Amorphous Silicon

IP.com Disclosure Number: IPCOM000040388D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kanicki, J: AUTHOR

Abstract

A technique is described whereby low resistance contact to hydrogenated amorphous silicon is achieved through the use of YxGdy alloys without the need of a heavily doped (n+-type) layer at the metal/a-Si:H interface. Such low resistance/direct ohmic simplifies the fabrication process of various a-Si:H devices, such as thin film transistors, Schottky diodes, p-i-n junctions, etc. True direct ohmic, non-rectifying or low resistance contact to undoped and n-type doped hydrogenated amorphous silicon films has been achieved by using YxGdy alloys without n+-type layers at the metal/a-Si:H interface. The electron concentration is increased in the region near the YxGdy/a-Si:H interface and the highest resistivity region is the bulk semiconductor (a-Si:H) region.

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True Direct Ohmic Contact to Hydrogenated Amorphous Silicon

A technique is described whereby low resistance contact to hydrogenated amorphous silicon is achieved through the use of YxGdy alloys without the need of a heavily doped (n+-type) layer at the metal/a-Si:H interface. Such low resistance/direct ohmic simplifies the fabrication process of various a-Si:H devices, such as thin film transistors, Schottky diodes, p-i-n junctions, etc. True direct ohmic, non-rectifying or low resistance contact to undoped and n-type doped hydrogenated amorphous silicon films has been achieved by using YxGdy alloys without n+-type layers at the metal/a-Si:H interface. The electron concentration is increased in the region near the YxGdy/a-Si:H interface and the highest resistivity region is the bulk semiconductor (a-Si:H) region. Therefore, the current will be determined by the resistance of the a-Si:H bulk region and will be independent of the direction of the applied bias. Consequently, no depletion region is formed in the semiconductor (a-Si:H) and there is no potential barrier for the electron flow, either from the a-Si:H towards the YxGdy or in the opposite direction. The YxGdy alloys deposited by electron beam evaporation at room temperature and the a-Si:H layer can be deposited by various techniques, such as PECVD, CVD, HOMCVD, sputtering, etc. Furthermore, the cross- contamination and generation of the deep gap states in a-Si:H films from PH3 used for the deposition of n+...