TWI436488B - A solar cell having a graded buffer layer - Google Patents

Description

Solar cell with gradient buffer layer

The present invention relates to a photovoltaic element, and more particularly to a solar cell having a graded buffer layer.

Photoelectric elements include many types, such as a light-emitting diode (LED), a solar cell (Solar Cell), or a photodiode (Photo Diode).

Due to the shortage of petrochemical energy and people's awareness of the importance of environmental protection, people have been actively researching and developing technologies related to alternative energy and renewable energy in recent years. Among them, solar cells are attracting the most attention. Mainly because solar cells can directly convert solar energy into electrical energy, and no harmful substances such as carbon dioxide or nitride are generated during power generation, and pollution is not caused to the environment. In the solar cell, the InGaP/GaAs/Ge three-junction solar cell has the greatest development potential. However, the lattice constants of InGaP, GaAs and Ge do not match each other. When the Ge cell is sequentially grown up to the GaAs cell and the InGaP cell, Lattice misalignment occurs between the crystal lattices, stress is generated, the quality of the epitaxial crystal is destroyed, and the energy conversion efficiency of the solar cell is lowered.

Inverted Metamorphic Multijunction (IMM) solar cells are GaInP cells and GaAs cells that are grown with lattice constants on a growing substrate, and then the lattice constants are not matched with GaInP cells and GaAs cells. The InGaAs battery removes the growth substrate by bonding a support substrate to the InGaAs battery to form an inverse metamorphic multi-junction (IMM) solar cell. This improves the epitaxial quality of the GaInP battery and the GaAs battery, and improves the energy conversion efficiency of the solar cell. However, in the InGaAs cell with lower energy gap, lattice misalignment still occurs, which reduces the epitaxial quality of the InGaAs cell.

The photovoltaic element such as a solar cell or the like may include a substrate and an electrode, and the substrate may be further connected to a substrate via a solder bump or a glue to form a light-emitting device or a light-absorbing device. In addition, the pedestal further has at least one circuit electrically connected to the electrodes of the photovoltaic element via a conductive structure, such as a metal line.

The reverse metamorphic multi-junction (IMM) solar cell of the first embodiment includes at least one support substrate; a bottom cell is disposed on the support substrate; a graded buffer layer is disposed on the bottom cell; and an intermediate cell is located in the gradient buffer layer Upper; and a top battery is located above the intermediate battery.

The embodiments of the present invention will be described in detail, and in the drawings, the same or the like

As shown in FIG. 1, an inverse metamorphic multi-junction (IMM) solar cell 1 includes a support substrate 10; a bottom cell 12 is disposed on the support substrate 10; and a gradient buffer layer 14 is disposed on the bottom cell 12; The intermediate battery 16 is located above the graded buffer layer 14; and a top cell 18 is located above the intermediate battery 16. . The energy gap of the top cell 18 is greater than the energy gap of the intermediate cell 16 and the bottom cell 12, and the material thereof comprises InGaP, InGaAs, AlGaAs or AlGaInP. The energy gap of the intermediate battery 16 is greater than the energy gap of the bottom cell 12, and the material thereof includes GaAs, GaInP, InGaAs, GaAsSb or InGaAsN. The material of the bottom cell 12 comprises Ge, GaAs or InGaAs. The top cell 18, the intermediate cell 16 and the bottom cell 12 can absorb light of different spectra and generate current.

As shown in FIG. 2, the gradation buffer layer 14 includes a first buffer layer 141 between the bottom cell 12 and the intermediate battery 16; a plurality of gradual auxiliary layers 142, 144, 146 and 148 are located in the first buffer layer 141 and the intermediate battery. 16; a plurality of erbium doped intermediate layers 143, 145 and 147 are located between a plurality of gradual subsidiary layers 142, 144, 146 and 148 adjacent to each other; and a second buffer layer 149 is located between the gradual auxiliary layer 148 and the middle Between the batteries 16. The gradation auxiliary layer of this embodiment is exemplified by four layers of 142, 144, 146 and 148, but is not limited thereto, and the number of the gradual auxiliary layers may be greater than four or less than four. The erbium-doped intermediate layer of this embodiment is exemplified by three layers of 143, 145 and 147, but is not limited thereto, and the number of the erbium-doped intermediate layer may also be greater than three or less than three. The material of the first buffer layer 141 comprises InGaAs, GaAs, AlGaAs, InGaP or AlGaInP; the material of the second buffer layer 149 comprises GaAs. The material of the plurality of auxiliary graded layers 142, 144, 146 and 148 comprises In _x Ga _(1-x) P, In _x Ga _(1-x) As or (Al _y Ga _(1-y) ) _x In _{(1- x)} As, wherein the In content x of the plurality of graded auxiliary layers is decreased from the support substrate toward the support substrate, and 0<x<1, 0<y<1. Gradient layers 142, 144, a plurality of affiliated with only 148 doped with n-type impurity such as silicon, sulfur or selenium, a concentration of about E17cm ^-3 -E20cm- ^3, is not doped with tellurium (Te). A plurality of germanium-doped intermediate layers 143, 145 and 147 are doped with germanium (Te) and n-type impurities, and have a thickness of about 1 -500 Wherein the n-type impurity is, for example, ruthenium, selenium or sulphur, the concentration is about E17 cm ^-3 -E20 cm ^-3 , and the ruthenium concentration is about E17 cm ^-3 -E20 cm ^-3 . The material of the plurality of erbium-doped intermediate layers 143, 145 and 147 comprises In _x Ga _(1-x) P, InGaAs or AlInGaAs, 0 < x < 1. Taking the erbium-doped intermediate layer 143 as an example, the method of forming the erbium-doped intermediate layer 143 includes continuing to pass the gas forming the graded subsidiary layer 144 after the growth chamber is formed into the graded subsidiary layer 144, and simultaneously introducing the n-type impurity. Si ₂ H ₆ and DETe having germanium impurities form an antimony doped intermediate layer 143, and the above-mentioned simultaneous introduction of the reaction gas having impurities is about 1-90 seconds, and the formation method of the antimony doped intermediate layers 145 and 147 The doped intermediate layer 143 is similar. Since the reverse metamorphic multi-junction (IMM) solar cell 1 is a top cell 18 and an intermediate cell 16 which are sequentially grown with a lattice constant matching on a growth substrate (not shown), the lattice constant is further increased with the top cell 18 The bottom battery 12, which is not matched with the intermediate battery 16, joins the support substrate 10 and the bottom battery 12, and then removes the growth substrate to form an inverse metamorphic multi-junction (IMM) solar cell 1, so the bottom battery 12 and the intermediate battery 16 There will be lattice misalignment between them. The gradient buffer layer 14 can reduce the occurrence of lattice misalignment between the bottom cell 12 and the intermediate cell 16, and can improve the epitaxial quality of the graded subsidiary layers 142, 144, 146 and 148, and help the gradient buffer layer 14 to lower the bottom cell 12 The stress generated by the lattice constant mismatch with the intermediate battery 16 enhances the epitaxial quality of the bottom cell 12.

The above-described embodiments are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Modifications and variations of the above-described embodiments can be made without departing from the spirit and scope of the invention. Therefore, the scope of the invention is as set forth in the appended claims.

1. . . Solar battery

10. . . Support substrate

12. . . Bottom battery

14. . . Gradient buffer layer

141. . . First buffer layer

142, 144, 146, 148. . . Gradient accessory layer

143, 145, 147. . . Antimony doped intermediate layer

149. . . Second buffer layer

16. . . Intermediate battery

18. . . Top battery

The drawings are intended to facilitate an understanding of the invention and are part of the specification. The embodiments of the drawings are described in conjunction with the embodiments to explain the principles of the invention.

Figure 1 is a cross-sectional view showing a first embodiment of the present invention.

Figure 2 is a cross-sectional view of a graded buffer layer in accordance with a first embodiment of the present invention.

14. . . Gradient buffer layer

141. . . First buffer layer

142, 144, 146, 148. . . Gradient accessory layer

143, 145, 147. . . Antimony doped intermediate layer

149. . . Second buffer layer

Claims (13)

a solar cell comprising: a support substrate; a bottom cell on the support substrate; a gradient buffer layer on the bottom cell, comprising: a plurality of In _x Ga _(1-x) P graded auxiliary layers, The In content x of the plurality of In _x Ga _(1-x) P graded auxiliary layers is decreased from the support substrate toward the support substrate, 0<x<1, and the plurality of In _x Ga _{(1-x) a} P-gradient subsidiary layer is not doped with germanium; and a germanium-doped intermediate layer between any two adjacent In _x Ga _(1-x) P graded subsidiary layers; an intermediate cell located in the gradient Above the buffer layer; and a top battery located above the intermediate battery. The solar cell of claim 1, wherein the gradient buffer layer further comprises: a first buffer layer between the bottom cell and the plurality of In _x Ga _(1-x) P graded auxiliary layers; A second buffer layer is disposed between the intermediate cell and the plurality of In _x Ga _(1-x) P graded subsidiary layers. The solar cell of claim 1, wherein the plurality of In _x Ga _(1-x) P graded subsidiary layers comprise n-type impurities. The solar cell of claim 1, wherein the ruthenium-doped intermediate layer comprises an n-type impurity. The solar cell of claim 1, wherein the material of the erbium-doped intermediate layer is selected from the group consisting of In _x Ga _(1-x) P, InGaAs, and AlInGaAs, 0 < x < 1. a solar cell comprising: a support substrate; a bottom battery on the support substrate; a graded buffer layer on the bottom cell, comprising: a plurality of graded auxiliary layers, wherein the plurality of graded subsidiary layers are not doped with germanium; and a germanium doping intermediate a layer between any two of the plurality of graded subsidiary layers adjacent to each other; an intermediate cell positioned over the graded buffer layer; and a top cell positioned over the intermediate cell. The solar cell of claim 6, wherein the plurality of graded subsidiary layers comprise n-type impurities. The solar cell of claim 6, wherein the material of the plurality of graded auxiliary layers is selected from the group consisting of In _x Ga _(1-x) P, In _x Ga _(1-x) As and (Al _y Ga _{(1-y) )} ) The group formed by _x In _(1-x) As, 0<x<1, 0<y<1. The solar cell of claim 8, wherein the In content x of the plurality of graded auxiliary layers decreases from the support substrate toward the support substrate. The solar cell of claim 6, wherein the ruthenium-doped intermediate layer comprises an n-type impurity. The solar cell according to claim 6, wherein the material of the erbium-doped intermediate layer is selected from the group consisting of In _x Ga _(1-x) P, InGaAs, and AlInGaAs, and 0 < x < 1. The solar cell of claim 6, wherein the gradient buffer layer further comprises: a first buffer layer between the bottom cell and the plurality of graded subsidiary layers; and a second buffer layer located in the intermediate battery Between the plurality of gradient auxiliary layers. The solar cell of claim 12, wherein the material of the first buffer layer is selected from the group consisting of InGaAs, GaAs, AlGaAs, InGaP, and AlGaInP. The group; and the material of the second buffer layer comprises GaAs.