High quality photovoltaic semiconductor material and laser ablation method of fabrication same
US5231047A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 1991 |
| Grant date | Jul 27, 1993 |
| Priority date | — |
| Expiry date | Dec 19, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/909
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A high quality, narrow band gap, hydrogenated amorphous germanium or amorphous silicon alloy material characterized by a host matrix in which all hydrogen is incorporated therein in germanium monohydride or silicon monohydride form, respectively; their mobility-lifetime product for non-equilibrium charge carriers is about 10.sup.-8 and about 10.sup.-7, respectively; their density of defect states in the band gap thereof is less than about 1.times.10.sup.17 and about 2.times.10.sup.16 /cm.sup.3, respectively; and their band gap is about 1.5 and about 0.9 eV, respectively. There is also disclosed a structure formed from a plurality of very thin layer pairs of hydrogenated amorphous germanium and amorphous silicon alloy material, each layer pair of which cooperates to provide narrow band gap material. From about 3 to about 7 atomic percent fluorine is added to the germanium and/or silicon alloy material so as to provide a strong bond (as compared to hydrogen) so as to provide reduced sensitivity to Stabler/Wronski degradation. The preferred method of fabricating such improved narrow band gap materials is through a laser ablation process in which hydrogen or fluorine gas is introduced …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.