TWI625865B - Solar cell structure and method for manufacturing the same - Google Patents

Abstract

A solar cell structure and a method of manufacturing the same. The solar cell structure includes a germanium substrate, a first passivation structure, and a second passivation structure. The crucible substrate has opposing first and second surfaces. The first passivation structure is overlying the first surface of the germanium substrate, wherein the first passivation structure comprises a first amorphous germanium dioxide passivation layer and a first intrinsic amorphous germanium passivation layer sequentially stacked on the first surface. The second passivation structure is overlying the second surface of the germanium substrate, wherein the second passivation structure comprises a second amorphous ceria passivation layer and a second intrinsic amorphous germanium passivation layer sequentially stacked on the second surface.

Description

Solar cell structure and manufacturing method thereof

The present invention relates to a photoelectric conversion device, and more particularly to a solar cell structure and a method of fabricating the same.

In solar cells, passivation structures and processes are indispensable for important structures and processes. Whether it is a traditional Back Surface Field (BSF) solar cell, or a Passiveated Emitter and Rear Cell (PERC) solar cell, or a Heterojunction with Intrinsic Thin Layer (HIT) ) Solar cells, all with a passivation layer. In order to make the passivation layer of these solar cells, a low pressure chemical vapor deposition (LPCVD) process is adopted, and the equipment of the low pressure chemical vapor deposition process is a vacuum device, so the equipment is expensive and the material selection is not satisfactory.

Therefore, the current process and materials of the passivation layer still have considerable room for improvement.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a solar cell structure and a method of fabricating the same that are provided with an amorphous ceria passivation layer and an intrinsic amorphous germanium passivation layer on opposite surfaces of the germanium substrate. Layer passivation layer structure. Since the amorphous ceria passivation layer can effectively passivate the surface of the ruthenium substrate, the problem of the ruthenium substrate interface defect can be solved, and the intrinsic amorphous ruthenium passivation layer with small energy gap and low impedance can be used to enhance the double passivation. The carrier conduction efficiency of the layer structure can effectively increase the open circuit voltage of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

Another object of the present invention is to provide a method for fabricating a solar cell structure which can form an amorphous ceria passivation layer on the surface of a tantalum substrate by a wet process in which a tantalum substrate is immersed in a solution having a nitric acid component. . Since the wet process for forming the amorphous ceria passivation layer can be performed in the same machine immediately after the other wet process and the wet cleaning process of the ruthenium substrate, the ruthenium substrate can be prevented from being contaminated by the external environment. In addition, the wet process allows the amorphous ceria passivation layer to be fully grown on the surface of the tantalum substrate. Therefore, the application of the method can greatly improve the passivation effect of the surface of the substrate.

According to the above object of the present invention, a solar cell structure is proposed. The solar cell structure includes a germanium substrate, a first passivation structure, and a second passivation structure. The crucible substrate has opposing first and second surfaces. The first passivation structure is overlying the first surface of the germanium substrate, wherein the first passivation structure comprises a first amorphous germanium dioxide passivation layer and a first intrinsic amorphous germanium passivation layer sequentially stacked on the first surface. The second passivation structure is overlying the second surface of the germanium substrate, wherein the second passivation structure comprises a second amorphous ceria passivation layer and a second intrinsic amorphous germanium passivation layer sequentially stacked on the second surface.

According to an embodiment of the invention, the material of the germanium substrate is a single crystal germanium or a polycrystalline germanium.

According to an embodiment of the invention, each of the first amorphous ceria passivation layer and the second amorphous ceria passivation layer has a thickness of from about 0.5 nm to about 3 nm.

According to an embodiment of the invention, each of the first intrinsic amorphous germanium passivation layer and the second intrinsic amorphous germanium passivation layer has a thickness of from about 0.5 nm to about 10 nm.

According to an embodiment of the invention, the refractive index of each of the first amorphous ceria passivation layer and the second amorphous ceria passivation layer at a wavelength of 500 nm is from about 1.40 to about 1.55.

According to an embodiment of the invention, the solar cell structure further includes a first doped germanium layer, a transparent conductive layer, a first electrode, a second doped germanium layer, and a second electrode. The first doped germanium layer is disposed on the first intrinsic amorphous germanium passivation layer. The transparent conductive layer is disposed on the first doped germanium layer, and the first electrode is disposed on a portion of the transparent conductive layer. The second doped germanium layer is disposed on the second intrinsic amorphous germanium passivation layer. The second electrode covers the second doped germanium layer.

According to an embodiment of the invention, the germanium substrate comprises a first doped region disposed adjacent to the first surface of the germanium substrate, and a second doped region disposed adjacent to the second surface of the germanium substrate. Moreover, the solar cell structure described above further includes a first electrode and a second electrode. The first electrode is disposed on the first passivation structure and the first passivation structure passing through the portion is in contact with the first doped region. The second electrode is disposed on the second passivation structure and the second passivation structure passing through the portion is in contact with the second doped region.

According to the above object of the present invention, a method of manufacturing a solar cell structure is further proposed. In this method, a germanium substrate is provided, wherein the germanium substrate has opposing first and second surfaces. Forming a first passivation structure overlying the first surface of the germanium substrate, wherein forming the first passivation structure comprises sequentially forming a first amorphous germanium passivation layer and a first intrinsic amorphous germanium passivation layer on the first surface. Forming a second passivation structure overlying the second surface of the germanium substrate, wherein forming the second passivation structure comprises sequentially forming a second amorphous germanium passivation layer and a second intrinsic amorphous germanium passivation layer on the second surface.

According to an embodiment of the invention, each of the first amorphous ceria passivation layer and the second amorphous ceria passivation layer has a thickness of from about 0.5 nm to about 3 nm.

According to an embodiment of the invention, each of the first intrinsic amorphous germanium passivation layer and the second intrinsic amorphous germanium passivation layer has a thickness of from about 0.5 nm to about 10 nm.

According to an embodiment of the invention, the method for fabricating the solar cell structure described above further comprises the following steps. A first doped germanium layer is formed on the first intrinsic amorphous germanium passivation layer. A transparent conductive layer is formed on the first doped germanium layer. The first electrode is formed on a portion of the transparent conductive layer. Forming a second doped germanium layer on the second intrinsic amorphous germanium passivation layer. Forming a second electrode overlying the second doped germanium layer.

According to an embodiment of the invention, forming each of the first amorphous ceria passivation layer and the second amorphous ceria passivation layer comprises immersing the ruthenium substrate in a solution having a nitric acid component.

According to an embodiment of the invention, each of the first amorphous ceria passivation layer and the second amorphous ceria passivation layer are formed by chemical vapor deposition or annealing.

100‧‧‧Solar cell structure

110‧‧‧矽 substrate

112‧‧‧ first surface

112a‧‧‧Rough structure

114‧‧‧ second surface

114a‧‧‧Rough structure

120‧‧‧First passivation structure

122‧‧‧First amorphous cerium oxide passivation layer

124‧‧‧First essential amorphous passivation layer

130‧‧‧Second passivation structure

132‧‧‧Second amorphous yttria passivation layer

134‧‧‧Second essential amorphous passivation layer

140‧‧‧First doped layer

150‧‧‧Second doped layer

160‧‧‧First electrode

170‧‧‧second electrode

180‧‧‧Transparent conductive layer

200‧‧‧ solar cell structure

210‧‧‧矽 substrate

212‧‧‧ first surface

212a‧‧‧Rough structure

214‧‧‧ second surface

216‧‧‧First doped area

218‧‧‧Second doped area

220‧‧‧First passivation structure

222‧‧‧First amorphous cerium oxide passivation layer

224‧‧‧First essential amorphous passivation layer

230‧‧‧Second passivation structure

232‧‧‧Second amorphous yttria passivation layer

234‧‧‧Second essential amorphous passivation layer

240‧‧‧first electrode

250‧‧‧second electrode

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; FIG. 2 is a schematic cross-sectional view showing a solar cell structure according to an embodiment of the present invention; and FIG. 3A to FIG. 3D are diagrams showing a solar cell according to an embodiment of the present invention. Schematic diagram of the process profile of the structure.

Please refer to FIG. 1 , which is a cross-sectional view showing a structure of a solar cell according to an embodiment of the present invention. In the present embodiment, the solar cell structure 100 is a heterojunction thin intrinsic layer solar cell structure. In some embodiments, the solar cell structure 100 can primarily include a germanium substrate 110, a first passivation structure 120, and a second passivation structure 130. The material of the germanium substrate 110 may be, for example, a single crystal germanium or a polycrystalline germanium. The 矽 substrate 110 has a first surface 112 and a second surface 114, wherein the first surface 112 and the second surface 114 are respectively located on opposite sides of the 矽 substrate 110. In some demonstration examples, 矽基 The first surface 112 and the second surface 114 of the plate 110 have rough structures 112a and 114a, respectively. For example, the roughness structures 112a and 114a can be pyramidal structures.

The first passivation structure 120 overlies the first surface 112 of the germanium substrate 110 to passivate the first surface 112. In the present embodiment, the first passivation structure 120 is a two-layer stacked structure. In some embodiments, the first passivation structure 120 includes a first amorphous ceria passivation layer 122 and a first intrinsic amorphous germanium passivation layer 124, wherein the first amorphous ceria passivation layer 122 covers the germanium substrate 110 On the first surface 112, a first intrinsic amorphous germanium passivation layer 124 is stacked on the first amorphous ceria passivation layer 122. Therefore, the first amorphous ceria passivation layer 122 is interposed between the first surface 112 of the germanium substrate 110 and the first intrinsic amorphous germanium passivation layer 124.

The first surface 112 of the germanium substrate 110 may have a plurality of floating bonds, and the first amorphous germanium passivation layer 122 may provide oxygen ions to bond with the floating bonds of the first surface 112 to achieve the effect of passivating the first surface 112. . Considering the energy gap and impedance of the first amorphous ceria passivation layer 122, the thickness of the first amorphous ceria passivation layer 122 should not be too thick, so that electrons and holes cannot be transmitted or the transfer efficiency is not good. On the other hand, since the first amorphous ceria passivation layer 122 cannot be too thick due to electrical considerations, in order to ensure the passivation effect of the first surface 112 of the tantalum substrate 110, the present embodiment is passivated in the first amorphous ceria. The first intrinsic amorphous germanium passivation layer 124 is additionally overlying the layer 122 to utilize the double passivation layer structure to achieve the effect of effectively passivating the first surface 112 and extending the life cycle of the carrier. Therefore, the open circuit voltage and conversion efficiency of the solar cell structure 100 can be effectively improved. In some exemplary examples, the first amorphous cerium oxide The passivation layer 122 may have a thickness of from about 0.5 nm to about 3 nm, and the first intrinsic amorphous germanium passivation layer 124 may have a thickness of from about 0.5 nm to about 10 nm. In addition, the refractive index of the first amorphous ceria passivation layer 122 at a wavelength of 500 nm is from about 1.40 to about 1.55.

As shown in FIG. 1, a second passivation structure 130 overlies the second surface 114 of the germanium substrate 110 to passivate the second surface 114. In the present embodiment, the second passivation structure 130 is also a two-layer stacked structure. In some embodiments, the second passivation structure 130 includes a second amorphous ceria passivation layer 132 and a second intrinsic amorphous passivation layer 134, wherein the second amorphous ceria passivation layer 132 covers the germanium substrate 110 On the second surface 114, a second intrinsic amorphous germanium passivation layer 134 is stacked on the second amorphous ceria passivation layer 132. Therefore, the second amorphous ceria passivation layer 132 is interposed between the second surface 114 of the tantalum substrate 110 and the second intrinsic amorphous passivation layer 134.

The second surface 114 of the germanium substrate 110 may also have a plurality of floating bonds, and the second amorphous germanium passivation layer 132 may provide oxygen to bond with the second surface 114 to passivate the second surface 114. Similarly, considering the energy gap and impedance of the second amorphous ceria passivation layer 132, the thickness of the second amorphous ceria passivation layer 132 should not be too thick to affect the transfer of electrons and holes. Since the second amorphous ceria passivation layer 132 cannot be too thick due to electrical considerations, in order to ensure the passivation effect of the second surface 114 of the germanium substrate 110, the present embodiment is also on the second amorphous ceria passivation layer 132. A second intrinsic amorphous germanium passivation layer 134 is overlying to utilize the dual layer intrinsic passivation layer structure to effectively passivate the second surface 114 and extend the carrier lifetime. In some exemplary examples, the thickness of the second amorphous ceria passivation layer 132 may range from about 0.5 nm to The thickness of the second intrinsic amorphous germanium passivation layer 134 may be from about 0.5 nm to about 10 nm, about 3 nm. In addition, the second amorphous ceria passivation layer 132 has a refractive index at a wavelength of 500 nm of from about 1.40 to about 1.55.

Cerium oxide is more stable than the common passivation material amorphous germanium hydride (a-Si:H), and unlike hydrogen in amorphous hydrazine hydride, it is easily removed due to temperature rise or sun exposure. Therefore, the first amorphous ceria passivation layer 122 and the second amorphous ceria passivation layer 132 can provide a better passivation effect of the first surface 112 and the second surface 114 of the germanium substrate 110.

Referring to FIG. 1 again, in some embodiments, the solar cell structure 100 further includes a first doped germanium layer 140, a second doped germanium layer 150, a first electrode 160, and a second electrode 170. The first doped germanium layer 140 is overlaid on the first intrinsic amorphous germanium passivation layer 122. The second doped germanium layer 150 is overlying the second intrinsic amorphous germanium passivation layer 132, and the first doped germanium layer 140 is located on opposite sides of the germanium substrate 110, respectively. The first doped germanium layer 140 is different from the second doped germanium layer 150 in conductivity type. The first type doped silicon layer 140 and 150 wherein one of the second conductivity type doping type is n-type silicon layer or n ⁺ type, and the other p-type or p ⁺ type. In some exemplary examples, the germanium substrate 110 is p-type, the first doped germanium layer 140 is n-type, and the second doped germanium layer 150 is p ⁺ -type.

The first electrode 160 is disposed on a portion of the first doped germanium layer 140. In some embodiments, the solar cell structure 100 further selectively includes a transparent conductive layer 180, wherein the transparent conductive layer 180 is first covered on the first doped germanium layer 140, and the first electrode 160 is disposed on a portion of the transparent conductive layer. On the layer 180, the first electrode 160 can be connected to the first doping type via the transparent conductive layer 180. The germanium layer 140 is electrically connected. The arrangement of the transparent conductive layer 180 can increase the current transfer efficiency, thereby improving the performance of the solar cell structure 100. The material of the transparent conductive layer 180 may be, for example, a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). As shown in FIG. 1, the second electrode 170 is overlaid on the second doped germanium layer 150.

Referring to FIG. 2, a cross-sectional view of a solar cell structure in accordance with an embodiment of the present invention is shown. In the present embodiment, the solar cell structure 200 is an emitter and back electrode passivated solar cell structure. In some embodiments, solar cell structure 200 can primarily include germanium substrate 210, first passivation structure 220, and second passivation structure 230. The material of the germanium substrate 210 may be, for example, a single crystal germanium or a polycrystalline germanium. The germanium substrate 210 has a first surface 212 and a second surface 214 that are opposite each other. In some exemplary examples, the first surface 212 of the germanium substrate 210 has a roughness 212a to increase the amount of light incident on the germanium substrate 210. The roughness 212a can be, for example, a pyramid structure.

The first passivation structure 220 overlies the first surface 212 of the germanium substrate 210 to passivate the first surface 212. The first passivation structure 220 is a two-layer stacked structure. In some embodiments, the first passivation structure 220 includes a first amorphous ceria passivation layer 222 and a first intrinsic amorphous passivation layer 224. The first amorphous germanium passivation layer 222 is overlying the first surface 212 of the germanium substrate 210, and the first intrinsic amorphous germanium passivation layer 224 is stacked on the first amorphous germanium passivation layer 222, ie, first. The amorphous ceria passivation layer 222 is interposed between the first surface 212 and the first intrinsic amorphous passivation layer 224.

The first surface 212 of the germanium substrate 210 may have a plurality of floating bonds, and the oxygen in the first amorphous germanium dioxide passivation layer 222 may be bonded to the floating bonds of the first surface 212, thereby achieving passivation of the first surface 212. effect. Since the first amorphous ceria passivation layer 222 has a large energy gap and a large impedance, the thickness of the first amorphous ceria passivation layer 222 cannot be too thick, so that electrons and holes cannot be transmitted or the transfer efficiency is not high. good. Since the first amorphous ceria passivation layer 222 is not too thick, the first amorphous ceria passivation layer 222 is further coated on the first amorphous ceria passivation layer 222 to strengthen the counter substrate. The passivation effect of the first surface 212 of 210. Therefore, with such a two-layer intrinsic passivation layer structure, not only the passivation effect on the first surface 212 but also the carrier life cycle can be enhanced. In some exemplary examples, the first amorphous ceria passivation layer 222 may have a thickness of from about 0.5 nm to about 3 nm, and the first intrinsic amorphous germanium passivation layer 224 may have a thickness of from about 0.5 nm to about 10 nm. In addition, the refractive index of the first amorphous ceria passivation layer 222 at a wavelength of 500 nm is from about 1.40 to about 1.55.

A second passivation structure 230 overlies the second surface 214 of the germanium substrate 210 to passivate the second surface 214. The second passivation structure 230 is also a two-layer stacked structure. In some embodiments, the second passivation structure 230 includes a second amorphous ceria passivation layer 232 and a second intrinsic amorphous passivation layer 234. The second amorphous germanium passivation layer 232 is overlying the second surface 214 of the germanium substrate 210, and the second intrinsic amorphous germanium passivation layer 234 is stacked on the second amorphous germanium passivation layer 232. Thus, the second amorphous ceria passivation layer 232 is interposed between the second surface 214 of the tantalum substrate 210 and the second intrinsic amorphous passivation layer 234.

The second surface 214 of the tantalum substrate 210 also has a plurality of floating bonds. The oxygen in the second amorphous ceria passivation layer 232 can be bonded to the floating bonds of the second surface 214 to passivate the second surface 214. Since the second amorphous ceria passivation layer 232 has a large energy gap and a large impedance, the thickness of the second amorphous ceria passivation layer 232 cannot be too thick to affect the transfer of carriers. The present embodiment covers a second intrinsic amorphous germanium passivation layer 234 on the second amorphous ceria passivation layer 232. By utilizing the two-layer intrinsic passivation layer structure, both the passivation quality of the second surface 214 and the extension of the carrier life cycle can be achieved. In some exemplary examples, the second amorphous ceria passivation layer 232 may have a thickness of from about 0.5 nm to about 3 nm, and the second intrinsic amorphous germanium passivation layer 234 may have a thickness of from about 0.5 nm to about 10 nm. In addition, the second amorphous ceria passivation layer 232 has a refractive index at a wavelength of 500 nm of from about 1.40 to about 1.55.

Referring again to FIG. 2 , in some embodiments, the germanium substrate 210 includes a first doped region 216 and a second doped region 218 . The first doped region 216 and the second doped region 218 are both disposed in the germanium substrate 210, wherein the first doped region 216 is adjacent to the first surface 212, and the second doped region 218 is adjacent to the second surface 214. . The first doped region 216 is different from the doped region 218 in conductivity type. The first doped region 216 and 218 wherein one of the second conductivity type region is doped n-type or n ⁺ type, and the other p-type or p ⁺ type. In some exemplary examples, the germanium substrate 210 is p-type, the first doped region 216 is n-type, and the second doped region 218 is p ⁺ -type.

The solar cell structure 200 may further include a first electrode 240 and a second electrode 250. The first electrode 240 is disposed on the first intrinsic amorphous passivation layer 224 of the first passivation structure 220, and sequentially passes through a portion of the first intrinsic amorphous passivation layer 224 and a portion of the first amorphous Cerium oxide The passivation layer 222 is in contact with the first doped region 216 to form an electrical connection. The second electrode 250 is disposed on the second intrinsic amorphous germanium passivation layer 234 of the second passivation structure 230, and sequentially passes through a portion of the second intrinsic amorphous germanium passivation layer 234 and a portion of the second amorphous dioxide. The passivation layer 232 is in contact with the second doped region 218 to form an electrical connection.

The fabrication of the passivation structure of the solar cell structure of the present invention will be described below by taking the manufacturing process of the solar cell structure 100 of FIG. 1 as an example.

Please refer to FIG. 3A to FIG. 3D , which are schematic cross-sectional views showing a process of a solar cell structure according to an embodiment of the present invention. In some embodiments, when the solar cell structure 100 shown in FIG. 1 is fabricated, the germanium substrate 110 may be provided first. The crucible substrate 110 has a first surface 112 and a second surface 114 opposite to each other. Next, as shown in FIG. 3A, a portion of the germanium substrate 110 may be selectively etched using, for example, a wet etching method, thereby forming rough structures 112a and 114a on the first surface 112 and the second surface 114 of the germanium substrate 110, respectively. .

Since the rough structures 112a and 114a are fabricated in a wet process, after the rough structures 112a and 114a are completed, the germanium substrate 110 can be wet-cleaned in-situ to remove residual etchant on the germanium substrate 110. Next, as shown in FIG. 3B, the first passivation structure 120 and the second passivation structure 130 may be formed to cover the first surface 112 and the second surface 114 of the germanium substrate 110, respectively. In some embodiments, when the first passivation structure 120 is formed, the first amorphous ceria passivation layer 122 may be formed on the first surface 112 of the germanium substrate 110, and then the first essence is formed by, for example, chemical vapor deposition. The amorphous passivation passivation layer 124 is on the first amorphous ceria passivation layer 122. same When the second passivation structure 130 is formed, the second amorphous ceria passivation layer 132 may be formed on the second surface 114 of the germanium substrate 110, and then the second intrinsic amorphous germanium is formed by, for example, chemical vapor deposition. The passivation layer 134 is on the second amorphous ceria passivation layer 132.

In some exemplary examples, the first amorphous ceria passivation layer 122 and the second amorphous ceria passivation layer 132 may each have a thickness of from about 0.5 nm to about 3 nm. The thickness of the first intrinsic amorphous germanium passivation layer 124 and the second intrinsic amorphous germanium passivation layer 134 may each be from about 0.5 nm to about 10 nm.

In some embodiments, when the first amorphous ceria passivation layer 122 and the second amorphous ceria passivation layer 132 are formed, the tantalum substrate 110 may be immersed in a solution having a nitric acid component. The surface portion of the ruthenium substrate 110 is oxidized by the nitric acid component in the solution, and ruthenium dioxide is formed on the surface of the ruthenium substrate 110, whereby the first surface 112 and the second surface 114 of the ruthenium substrate 110 can be simultaneously formed. An amorphous ceria passivation layer 122 and a second amorphous ceria passivation layer 132.

In such an embodiment, since the process of immersing the ruthenium substrate 110 in the solution having the nitric acid component is a wet process, the immersion of the ruthenium substrate can be performed in the original place after the wet etching and the wet cleaning of the ruthenium substrate 110. Process, no need to switch to other process machines. Therefore, before the germanium substrate 110 contacts the external environment, the first surface 112 and the second surface 114 of the germanium substrate 110 are respectively covered with the first amorphous germanium dioxide passivation layer 122 and the second amorphous germanium dioxide passivation layer, respectively. 132. In this way, the ruthenium substrate 110 can be prevented from being contaminated during the conversion process. Further, when the cerium oxide is grown by soaking the solution having the nitric acid component, the solution can easily enter the recesses of the rough structures 112a and 114.a of the ruthenium substrate 110, so that the first surface of the ruthenium substrate 110 can be made. 112 and the second surface 114 are subjected to comprehensive oxidation, thereby further growing the first amorphous ceria passivation layer 122 and the second amorphous ceria passivation layer 132 on the first surface 112 and the second surface 114, respectively. on. Therefore, the passivation quality of the first amorphous ceria passivation layer 122 and the second amorphous ceria passivation layer 132 can be greatly improved.

In other examples, the first amorphous ceria passivation layer 122 and the second amorphous ceria passivation layer 132 may also be formed by chemical vapor deposition (CVD) or annealing. In the example of the chemical vapor deposition method, the first amorphous ceria passivation layer 122 and the second amorphous ceria passivation layer 132 are not formed at the same time, and the order in which they are formed may be adjusted according to process requirements. In the example of the annealing mode, the first amorphous ceria passivation layer 122 and the second amorphous ceria passivation layer 132 may be simultaneously formed.

As shown in FIG. 3C, after the first passivation structure 120 and the second passivation structure 130 are completed, the first doped germanium layer 140 is formed on the first intrinsic amorphous germanium passivation layer 124 by, for example, chemical vapor deposition. Also, the second doped germanium layer 150 is formed on the second intrinsic amorphous germanium passivation layer 134 by, for example, chemical vapor deposition.

As shown in FIG. 3D, in some embodiments, a transparent conductive layer 180 may be selectively formed by physical vapor deposition (PVD) to cover the first doped germanium layer 140. The first electrode 160 is formed on the portion of the transparent conductive layer 180 by, for example, a screen printing method. In addition, the second electrode 170 is formed on the second doped germanium layer 150 by, for example, physical vapor deposition, and the fabrication of the solar cell structure 100 is substantially completed.

It can be seen from the above embodiments that one of the advantages of the present invention is that the present invention provides a double passivation layer structure composed of an amorphous ceria passivation layer and an intrinsic amorphous germanium passivation layer on opposite surfaces of the germanium substrate. . Since the amorphous ceria passivation layer can effectively passivate the surface of the ruthenium substrate, the problem of the ruthenium substrate interface defect can be solved, and the intrinsic amorphous ruthenium passivation layer with small energy gap and low impedance can be used to enhance the double passivation. The conductivity of the layer structure can effectively increase the open circuit voltage of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

From the above embodiments, another advantage of the present invention is that the present invention can form an amorphous ceria passivation layer on the surface of the tantalum substrate by a wet process in which the tantalum substrate is immersed in a solution having a nitric acid component. Since the wet process for forming the amorphous ceria passivation layer can be performed in the same machine immediately after the other wet process and the wet cleaning process of the ruthenium substrate, the ruthenium substrate can be prevented from being contaminated by the external environment. In addition, the wet process allows the amorphous ceria passivation layer to be fully grown on the surface of the tantalum substrate. Therefore, the application of the method can greatly improve the passivation effect of the surface of the substrate.

While the present invention has been described above by way of example, it is not intended to be construed as a limitation of the scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

Claims (4)

A method of fabricating a solar cell structure, comprising: providing a germanium substrate, wherein the germanium substrate has a first surface and a second surface; forming a first passivation structure overlying the first surface, wherein the first surface is formed a passivation structure includes sequentially forming a first amorphous germanium dioxide passivation layer and a first intrinsic amorphous germanium passivation layer on the first surface; and forming a second passivation structure overlying the second surface, Forming the second passivation structure includes sequentially forming a second amorphous ceria passivation layer and a second intrinsic amorphous passivation layer on the second surface, wherein each of the first amorphous dioxide is formed The tantalum passivation layer and the second amorphous ceria passivation layer comprise immersing the tantalum substrate in a solution having a nitric acid component. The method of manufacturing a solar cell structure according to claim 1, wherein each of the first amorphous ceria passivation layer and the second amorphous ceria passivation layer has a thickness of from 0.5 nm to 3 nm. The method of manufacturing a solar cell structure according to claim 1, wherein each of the first intrinsic amorphous passivation layer and the second intrinsic amorphous passivation layer has a thickness of from 0.5 nm to 10 nm. The method for manufacturing a solar cell structure according to claim 1 of the patent scope further includes: Forming a first doped germanium layer on the first intrinsic amorphous germanium passivation layer; forming a transparent conductive layer on the first doped germanium layer; forming a first electrode in the portion of the transparent conductive layer Forming a second doped germanium layer on the second intrinsic amorphous germanium passivation layer; and forming a second electrode overlying the second doped germanium layer.