Batteries: thermoelectric and photoelectric – Photoelectric – Cells
Reexamination Certificate
2000-03-16
2001-06-05
Diamond, Alan (Department: 1753)
Batteries: thermoelectric and photoelectric
Photoelectric
Cells
C136S256000, C136S258000, C257S458000, C257S461000, C257S464000, C257S431000, C438S087000, C438S088000, C438S096000, C438S097000, C438S057000, C438S061000
Reexamination Certificate
active
06242687
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present application relates to a process for providing photovoltaic thin film semiconductor devices, in particular solar cells and other devices obtainable by such a process. This film semiconducting devices have a wide variety of applications. For example, solar cells incorporating amorphous silicon, microcrystalline silicon or polycrystalline silicon are employed to generate electricity from incident irradiation.
2. Background of the Prior Art
U.S. Pat. No. 4,721,535 discloses a solar cell wherein the p-type layer consists of three layers, which all comprise carbon and of which the middle layer is doped with Boron. As the composition is varied step wise, such layers can not be produced in a continuous process.
In the article “Fabrication of single pin type solar cells with high conversion efficiency of 13.0%” by K. Miyachi et al., a p-type layer is disclosed, which consists of two graded layers. In the first layer, the Carbon concentration is increased by increasing the proportion of dimethyl relative to silane. In the second layer this proportion in decreased. In this publication no doping of the layers is disclosed.
In the European patent application EP-A-0 437 767 a a-SiGe:H is disclosed, wherein a high band gap in the n-type layer is achieved by adding Carbon or Nitrogen. This will cause problems regarding alignment of the bands and a barrier between which the layer will be generated.
SUMMARY OF THE INVENTION
The present invention provides a process in which all the layers of a solar cell, including p-type and/or n-type graded layers are formed in a continuous way. Further the present invention provides a solar cell with high efficiency and produced according to this process.
According to the present invention a process for producing a thin film semiconductor solar cell, said solar cell at least comprising:
a p-type layer; and
an n-type layer, which are deposited on carrier material,
wherein the composition of the p-type layer, especially the optical band gap and/or the specific conductivity, and/or the composition of the n-type layer, especially the optical band gap and/or the specific conductivity thereof, are varied in a continuous way in time and/or space, by controlling the composition and/or flow of predetermined gasses at the location where the respective semiconductor layer is formed.
Further the present invention provides a thin film semiconductor solar cell, comprising:
a substrate of carrier material;
a p-type layer provided on the substrate; and
an n-type layer provided above the p-type layer, wherein the optical band gap and/or the specific conductivity of either the p-type layer or the n-type layer vary spatially.
REFERENCES:
patent: 4160678 (1979-07-01), Jain et al.
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patent: 4598164 (1986-07-01), Tiedje et al.
patent: 4680607 (1987-07-01), Fukatsu et al.
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patent: 4721535 (1988-01-01), Itoh et al.
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patent: 0437767 (1991-07-01), None
K. Miyachi et al., “Fabrication of Single Pin Type Solar Cells with a High Conversion Efficiency of 13.0% Photovoltaic Solar Energy Conference,” Oct. 1992, pp. 88-91.
M.W.M. van Cleef et al., “Microcrystalline-Crystalline Silicon Heterojunction Solar Cells Using Highly Conductive Thin P-Type Microcrystalline Silicon Window Layers,” 25th PVSC; May 1996; pp. 42-43.
J.K. Rath et al., “Development of Amorphous Silicon Based P-I-N Solar Cell in A Superstrate Structure Wtih P-Microcrystalline Silicon as Window Layer,” 25th PVSC; May 1996; pp. 1101-1104.
R.E.I. Schropp et al., “Bandgap-, dopant-, and defect-graded dual-junction amorphous silicon solar cells”, European Photovoltaic Solar Energy Conference, Apr. 1994, pp. 699-702.
Diamond Alan
Universiteit van Utrecth
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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