Patent Application
20110120549
This application claims the priority benefits of Taiwan patent application serial no. 98139580, filed on Nov. 20, 2009, and application serial no. 98139550, filed on Nov. 20, 2009. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of specification.
1. Field of Invention
The present invention relates to a solar cell and a manufacturing method thereof, and more generally to a thin film solar cell with higher photoelectric conversion efficiency and a manufacturing method thereof.
2. Description of Related Art
Solar cells using monocrystalline silicon or polycrystalline silicon account for more than 90% in the solar cell market. However, these solar cells are made from silicon wafers of 150 μm to 350 μm thick, and the process cost thereof is higher. In addition, the raw materials of solar cells are silicon ingots with high quality. The silicon ingots face the shortage problem as the usage quantity thereof is increased significantly in recent years. Therefore, the thin film solar cell has been the new focus due to the advantages of low cost, easy for large-area production and simple module process, etc.
Generally speaking, in a conventional thin film solar cell, an electrode layer, a photovoltaic layer and another electrode layer are sequentially blanket-stacked on a substrate. During the process of stacking these layers, these layers are patterned by performing laser cutting processes, so as to form a plurality of sub cells connected in series. When a light enters the thin film solar cell from outside, free electron-hole pairs are generated in the photovoltaic layer by the solar energy, and the internal electric field formed by the PN junction makes electrons and holes respectively move toward two layers, so as to generate a storage state of electricity. Meanwhile, if a load circuit or an electronic device is connected, the electricity can be provided to drive the circuit or device.
However, the conventional thin film solar cell still has room for improving the whole photoelectric conversion efficiency thereof. Accordingly, more attention has been drawn on how to improve the photoelectric conversion efficiency and electrical performance of the conventional thin film solar cell so as to enhance the whole competitiveness of the products.
The present invention provides a thin film solar cell, in which the light utilization rate is effectively enhanced and the recombination of electron-hole pairs on the surface is lowered, so as to achieve higher photoelectric conversion efficiency.
The present invention provides a manufacturing method to form the above-mentioned thin film solar cell.
The present invention further provides a method for increasing carrier mobility in a semiconductor device, in which a neutron treatment step is performed to the silicon substrate with boron dopants, so as to increase the carrier mobility and further enhance the performance of the device.
The prevent invention also provides a semiconductor device with higher carrier mobility.
The present invention provides a thin film solar cell including a substrate, a first conductive layer, a photovoltaic layer and a second conductive layer. The first conductive layer is doped with boron atoms so as to have a texture structure. Isotope B10 doped in the first conductive layer accounts for more than 19.9% relative to the total boron atoms. The first conductive layer is disposed on the substrate. The photovoltaic layer is disposed on the first conductive layer. The second conductive layer is disposed on the photovoltaic layer.
According to an embodiment of the present invention, the first conductive layer includes at least one of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), zinc oxide, aluminium tin oxide (ATO), aluminium zinc oxide (AZO), cadmium indium oxide (CIO), cadmium zinc oxide (CZO), gallium zinc oxide (GZO) and fluorine tin oxide (FTO).
According to an embodiment of the present invention, the photovoltaic layer is a Group IV thin film, a III-V compound semiconductor thin film, a II-VI compound semiconductor thin film or an organic compound semiconductor thin film. In an embodiment, the Group IV thin film comprises at least one of an amorphous silicon (a-Si) thin film, a microcrystalline silicon (μc-Si) thin film, an amorphous silicon germanium (a-SiGe) thin film, a microcrystalline silicon germanium (μc-SiGe) thin film, an amorphous silicon carbide (a-SiC) thin film, a microcrystalline silicon carbide (μc-SiC) thin film, a tandem silicon thin film and a triple silicon thin film. In an embodiment, the III-V compound semiconductor thin film comprises gallium arsenide (GaAs) or indium gallium phosphide (InGaP). In an embodiment, the II-VI compound semiconductor thin film includes copper indium diselenide (CIS), copper indium gallium diselenide (CIGS), cadmium telluride (CdTe) or a combination thereof. In an embodiment, the organic compound semiconductor thin film includes a mixture of poly(3-hexylthiophene) (P3HT) and PCBM.
According to an embodiment of the present invention, the first conductive layer is a transparent conductive layer, and the second conductive layer includes at least one of a reflective layer and a transparent conductive layer.
The present invention provides a manufacturing method of a thin film solar cell. A substrate is provided. A first conductive layer is formed on the substrate. Boron atoms are doped in the first conductive layer so as to form a texture structure on a surface of the first conductive layer, wherein isotope B10 doped in the first conductive layer accounts for more than 19.9% relative to the total boron atoms. A photovoltaic layer is formed on the first conductive layer. A second conductive layer is formed on the photovoltaic layer.
According to an embodiment of the present invention, the method of doping the boron atoms includes an ion implantation process or a plasma doping process.
According to an embodiment of the present invention, the manufacturing method further includes performing a neutron treatment process to the first conductive layer doped with the boron atoms.
According to an embodiment of the present invention, the manufacturing method further includes performing a laser process to pattern the first conductive layer, so as to form a plurality of openings therein to expose the substrate.
According to an embodiment of the present invention, the manufacturing method further includes performing a laser process to pattern the photovoltaic layer, so as to form a plurality of openings therein to expose the first conductive layer.
According to an embodiment of the present invention, the manufacturing method further includes performing a laser process to pattern the second conductive layer, so as to form a plurality of openings therein to expose the first conductive layer.
According to an embodiment of the present invention, the method of forming the photovoltaic layer includes performing a radio frequency plasma enhanced chemical vapour deposition (RF PECVD) process, a vary high frequency plasma enhanced chemical vapour deposition (VHF CVD) process or a microwave plasma enhanced chemical vapour deposition (MW PECVD) process.
According to an embodiment of the present invention, the method of forming the second conductive layer includes forming at least one of a transparent conductive layer and a reflective layer on the photovoltaic layer, and the first conductive layer is a transparent conductive layer.
The present invention provides a method for increasing carrier mobility in a semiconductor device. A silicon substrate is provided. A boron doping step is performed to the silicon substrate. A neutron treatment step is performed to the silicon substrate.
According to an embodiment of the present invention, the material of the silicon substrate includes amorphous silicon or microcrystalline silicon.
According to an embodiment of the present invention, the boron doping step includes an boron ion implantation process.
According to an embodiment of the present invention, the neutron treatment step includes providing a neutron source, and directing neutrons generated from the neutron source to the silicon substrate.
According to an embodiment of the present invention, the neutron source includes a neutron generator.
According to an embodiment of the present invention, the boron doping step forms a doped region in the silicon substrate.
According to an embodiment of the present invention, the doped region is a source/drain region in a P-type metal oxide semiconductor (PMOS) transistor.
According to an embodiment of the present invention, the doped region is a source/drain region in a non-volatile memory device.
According to an embodiment of the present invention, the silicon substrate is a semiconductor layer in a solar cell.
According to an embodiment of the present invention, the silicon substrate is a P-type polysilicon gate.
The present invention further provides a semiconductor device including a silicon substrate and a boron doped region. The boron doped region is disposed in at least a portion of the silicon substrate, wherein neutrons are absorbed to the boron doped region.
According to an embodiment of the present invention, the material of the silicon substrate includes amorphous silicon or microcrystalline silicon.
According to an embodiment of the present invention, the boron doped region is a source/drain region in a P-type metal oxide semiconductor (PMOS) transistor.
According to an embodiment of the present invention, the boron doped region is a source/drain region in a non-volatile memory device.
According to an embodiment of the present invention, the silicon substrate is a semiconductor layer in a solar cell.
According to an embodiment of the present invention, the silicon substrate is a P-type polysilicon gate.
In view of the above, in the thin film solar cell of the present invention, the first conductive layer is doped with boron atoms so as to have a texture structure, and isotope B10 doped in the first conductive layer accounts for more than 19.9% relative to the total boron atoms. Therefore, the utilization rate of the light incident to the interior of the thin film solar cell is enhanced, the dangling bonds between the first conductive layer and the photovoltaic layer is decreased, and possibility of the recombination of electron-hole pairs on the surface is avoided. In addition, the present invention further provides a manufacturing method to form the above-mentioned thin film solar cell.
Moreover, in the present invention, a neutron treatment step is performed to the silicon substrate with boron dopants to increase carrier mobility, and thus, the operation speed of the device is enhanced and the performance of the device is further improved.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, a preferred embodiment accompanied with figures is described in detail below.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The first conductive layer 120 is doped with boron atoms so as to have a texture structure 122, and isotope B10 doped in the first conductive layer 120 accounts for more than 19.9% relative to the total boron atoms. The first conductive layer 120 is disposed on the substrate 110, as shown in
In details, the first conductive layer 120 is doped with boron atoms, so that the texture structure 122 as shown in
Referring to
That is, the thin film solar cell 100 can at least include the film layer structure of an amorphous silicon thin film solar cell, a microcrystalline silicon thin film solar cell, a tandem thin film solar cell, a triple thin film solar cell, a CIS thin film solar cell, a CIGS thin film solar cell, a GdTe thin film solar cell or an organic thin film solar cell. In other words, the photovoltaic layer 130 of this embodiment is provided only for illustration purposes, and can be decided according to the users' requirements. The thin film solar cell 100 can also include the film layer structure of another suitable thin film solar cell. In an embodiment, when the photovoltaic layer 130 of the thin film solar cell 100 is a tandem structure, it can be a stacked layer of amorphous silicon and microcrystalline silicon.
In this embodiment, a plurality of dangling bonds are present on the contact surface between the first conductive layer 120 and the photovoltaic layer 130. Besides, isotope B10 doped in the first conductive layer 120 of this embodiments accounts for more than 19.9% relative to the total boron atoms, and neutrons are absorbed to isotope B10. Accordingly, after a neutron treatment process is performed to the first conductive layer 120, the amount of the dangling bonds between the first conductive layer 120 and the photovoltaic layer 130 can be effectively decreased. Therefore, the possibility of the recombination of electron-hole pairs on the surface of the photovoltaic layer 130 is lowered, and the electrical performance and photoelectric conversion efficiency of the thin film solar cell 100 are further improved.
In other words, in this embodiment, the texture structure 120 is formed mainly by depositing boron atoms on the first conductive layer 120, and thus, the efficiency of the light incident to the thin film solar cell 100 is enhanced, the whole conductivity of the first conductive layer 120 is increased, and the whole electrical performance of the thin film solar cell 100 is further improved. Meanwhile, isotope B10 doped in the first conductive layer 120 accounts for more than 19.9% relative to the total boron atoms, so that after a neutron treatment is performed to the first conductive layer 120, the dangling bonds between the first conductive layer 120 and the photovoltaic layer 130 is reduced, and the electrical performance and photoelectric conversion efficiency of the thin film solar cell 100 is further improved.
Referring again to
In view of the above, the thin film solar cell 100 is irradiated by light (not shown) to generate electron-hole pairs. The first conductive layer 120 of the thin film solar cell 100 is doped with boron atoms so as to form the texture structure 122, and isotope B10 doped in the first conductive layer 120 accounts for more than 19.9% relative to the total boron atoms. Accordingly, the efficiency of the light incident to the thin film solar cell 100 is enhanced, the whole conductivity of the first conductive layer 120 is increased. Further, a neutron treatment process can be performed to the first conductive layer 120 to lower the dangling bonds between the first conductive layer 120 and the photovoltaic layer 130, so as to improve the photoelectric efficiency of the thin film solar cell 100.
In addition, the present invention also provides a manufacturing method to form the above-mentioned thin film solar cell 100, which is described in the following.
Referring to
Thereafter, boron atoms are doped in the first conductive layer 120, so as to form a texture structure 122 on the surface 120a of the first conductive layer 120, and isotope B10 doped in the first conductive layer 120 accounts for more than 19.9% relative to the total boron atoms, as shown in
Referring to
Referring to
Referring to
Referring to
Referring to
In this embodiment, the second conductive layer 140 is a stacked structure of a transparent conductive layer and a reflective layer, and the first conductive layer 120 is a transparent conductive layer, for example. Herein, a transparent conductive layer is formed on the photovoltaic layer 130, and a reflective layer is formed on the transparent conductive layer, so as to form the second conductive layer 140. Accordingly, a thin film solar cell with one-sided illumination is formed.
It is noted that a neutron treatment process can be performed to the first conductive layer 120 in any step after the photovoltaic layer 130 is formed on the first conductive layer 120, so as to reduce the dangling bonds present between the first conductive layer 120 and the photovoltaic layer 130, and further improve the photoelectric conversion efficiency of the thin film solar cell 100.
In addition, another thin film solar cell 200 is provided, as shown in
Thereafter, a boron doping step is performed to the silicon substrate in the step 402. The boron doping step is a boron ion implantation process to implant boron ions in the silicon substrate, for example. In addition, a heating process can be optionally performed after the boron doping step, so as to further diffuse the boron ions in the silicon substrate. In an embodiment, a doped region is formed in the silicon substrate after the boron doping step. Specifically, when the silicon substrate is a substrate of a P-type metal oxide semiconductor (PMOS) transistor, a P-type source/drain region is formed in the silicon substrate in the boron doping step. When the silicon substrate is a substrate of a non-volatile memory device, a source/drain region is formed in the silicon substrate in the boron doping step. In another embodiment, the boron doping step can be performed to the whole silicon substrate. For example, a P-type semiconductor layer in a solar cell can be formed by the boron doping step. Further, in another embodiment, the silicon substrate can be a P-type polysilicon gate in a MOS transistor or a memory device.
Afterwards, a neutron treatment step is performed to the silicon substrate in the step 404, so that neutrons are absorbed to the boron dopants in the silicon substrate. In details, when the neutrons are absorbed to the boron dopants, the dangling bonds are saturated to increase carrier mobility and further enhance the operation speed of the device. The neutron treatment step includes providing a neutron source, and then directing neutrons generated from the neutron source to the silicon substrate. In an embodiment, the neutron source is a neutron generator, for example.
In summary, the thin film solar cell of the present invention and the manufacturing method thereof at least have the following advantages. First, boron atoms are disposed on the first conductive layer so as to form a texture structure. Therefore, the utilization rate of the light incident to the interior of the thin film solar cell is enhanced, the whole conductivity of the first conductive layer is increased, and the whole electrical performance of the thin film solar cell is further improved. In addition, isotope B10 doped in the first conductive layer accounts for more than 19.9% relative to the total boron atoms, and after a neutron treatment is performed to the first conductive layer, the dangling bonds between the first conductive layer and the photovoltaic layer are reduced, and the electrical performance and whole photoelectric conversion efficiency of the thin film solar cell are further improved.
Besides, in the manufacturing method of the present invention, a simple process step can be performed to form the above-mentioned texture structure, so as to form the above-mentioned thin film solar cell. Moreover, by performing a neutron treatment step to the first conductive layer, the dangling bonds between the first conductive layer and the photovoltaic layer are reduced to further improve the whole photoelectric conversion efficiency of the thin film solar cell.
Also, in the present invention, a neutron treatment step can be performed to the silicon substrate with boron dopants, so as to saturate the dangling bonds. Accordingly, the operation speed of the device is enhanced and the performance of the device is further improved.
The present invention has been disclosed above in the preferred embodiments, but is not limited to those. It is known to persons skilled in the art that some modifications and innovations may be made without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 98139550 | Nov 2009 | TW | national |
| 98139580 | Nov 2009 | TW | national |
