U.S. patent application number 14/161255 was filed with the patent office on 2014-05-15 for tandem solar cell.
This patent application is currently assigned to EPISTAR CORPORATION. The applicant listed for this patent is EPISTAR CORPORATION. Invention is credited to Rong-Ren LEE, Shih-Chang LEE, Yung-Szu SU.
Application Number | 20140134783 14/161255 |
Document ID | / |
Family ID | 42318175 |
Filed Date | 2014-05-15 |
United States Patent
Application |
20140134783 |
Kind Code |
A1 |
LEE; Rong-Ren ; et
al. |
May 15, 2014 |
TANDEM SOLAR CELL
Abstract
This application is related to a method of manufacturing a solar
cell device comprising providing a substrate comprising Ge or GaAs;
forming a first tunnel junction on the substrate, wherein the first
tunnel junction comprises a first n-type layer comprising InGaP:Te,
and a first alloy layer comprising AlxGa(1-x)As and having a
lattice constant; adding a material into the first alloy layer to
change the lattice constant; and forming a first p-n junction on
the first tunnel junction.
Inventors: |
LEE; Rong-Ren; (Hsinchu,
TW) ; SU; Yung-Szu; (Hsinchu, TW) ; LEE;
Shih-Chang; (Hsinchu, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EPISTAR CORPORATION |
Hsinchu |
|
TW |
|
|
Assignee: |
EPISTAR CORPORATION
Hsinchu
TW
|
Family ID: |
42318175 |
Appl. No.: |
14/161255 |
Filed: |
January 22, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12686169 |
Jan 12, 2010 |
|
|
|
14161255 |
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Current U.S.
Class: |
438/93 |
Current CPC
Class: |
Y02E 10/50 20130101;
H01L 31/18 20130101; H01L 31/0725 20130101 |
Class at
Publication: |
438/93 |
International
Class: |
H01L 31/18 20060101
H01L031/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 12, 2009 |
TW |
098100992 |
Claims
1. A method of manufacturing a solar cell device, comprising:
providing a substrate comprising Ge or GaAs; forming a first tunnel
junction on the substrate, wherein the first tunnel junction
comprises a first n-type layer comprising InGaP:Te, and a first
alloy layer comprising Al.sub.xGa.sub.(1-x)As and having a lattice
constant; adding a material into the first alloy layer to change
the lattice constant; and forming a first p-n junction on the first
tunnel junction.
2. The method of claim 1, wherein the first alloy layer has a
p-type impurity.
3. The method of claim I, wherein the first n-type layer or the
first p-n junction comprises an element selected from the group
consisting of Gallium, Aluminum, Indium, Arsenic, and
Phosphorous.
4. The method of claim 1, further comprising a step of forming a
second tunnel junction on the first p-n junction, wherein the
second tunnel junction comprises a first element with an atomic
number larger than that of Gallium.
5. The method of claim 4, wherein the first element has a
concentration of 1.about.2%.
6. The method of claim 4, wherein the second tunnel junction
comprises a second alloy layer and a second n-type layer between
the second alloy layer and the substrate.
7. The method of claim 4, further comprising: forming a third
tunnel junction on the second tunnel junction, wherein the third
tunnel junction comprises a third alloy layer having a second
element with an atomic number larger than that of Gallium; and
forming a second p-n junction on the third tunnel junction.
8. The method of claim 7, wherein the second element has a
concentration between 3.5.times.10.sup.21 and
1.7.times.10.sup.22(l/cm.sup.3).
9. The method of claim 1, further comprising a step of forming a
buffer layer between the first tunnel junction and the
substrate.
10. The method of claim 9, wherein the buffer layer, the first
tunnel junction, or the first p-n junction comprises an element
selected from the group consisted of Gallium, Aluminum, Indium,
Arsenic, and Phosphorous.
11. The method of claim 1, wherein the material added into the
first alloy has a concentration between 1.about.2%.
12. The method of claim 1, wherein the material is selected from
the group consisting of Gallium, Aluminum, indium, Arsenic, and
Phosphorous.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application is a division application of a filed U.S.
application Ser. No. 12/686169 filed on Jan. 12, 2010, entitled as
`TANDEM SOLAR CELL".
BACKGROUND
[0002] 1. Technical Field
[0003] This application is related to a tandem solar cell
structure.
[0004] 2. Description of the Related Art
[0005] The solar cell is an energy transferring optoelectronic
device that receives sunlight and transfers it into electrical
energy.
[0006] The tandem solar cell or the multi-junction solar cell
stacks two or more than two p-n junction elements in series with
the same or different energy bandgaps. In general, the p-n junction
element which can absorb higher energy spectrum is formed as the
upper layer; the p-n junction element which can absorb lower energy
spectrum is formed as the bottom layer. By combining the p-n
junction elements of different materials, the photon energy can be
absorbed layer by layer. It can raise the absorbing rate and
efficiency, and decrease the transferring loss.
[0007] FIG. 1 illustrates a cross-sectional view of the
conventional tandem solar cell structure including a substrate 101,
a buffer layer 102, a tunnel junction 103 and a p-n junction 104.
Currently, the wildly used tunnel junction 103 includes a heavily
doped n-type layer (n++) 1031 and a heavily doped p-type layer
(p++) 1032 wherein the heavily doped n-type layer (n++) is
generally doped with Silicon, Tellurium or Selenium. The heavily
doped p-type layer (p++) 1032 is generally doped with Carbon, Zinc,
Magnesium or Beryllium. The lattice constant of the heavily doped
p-type layer (p++) 1032 is decreased after doped with Carbon. It
increases the lattice constant difference of the tunnel junction
103 and the substrate 101 and impairs the epitaxial quality and the
effect of the tunnel junction 103.
SUMMARY
[0008] This application is related to a method of manufacturing a
solar cell device, comprising providing a substrate comprising Ge
or GaAs; forming a first tunnel junction on the substrate, wherein
the first tunnel junction comprises a first n-type layer comprising
InGaP:Te, and a first alloy layer comprising Al.sub.xGa.sub.(1-x)As
and having a lattice constant; adding a material into the first
alloy layer to change the lattice constant; and forming a first p-n
junction on the first tunnel junction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The accompanying drawings are included to provide easy
understanding of the application, and are incorporated herein and
constitute a part of this specification. The drawings illustrate
embodiments of the application and, together with the description,
serve to illustrate the principles of the application.
[0010] FIG. 1 illustrates a cross-sectional view of the
conventional tandem solar cell structure.
[0011] FIG. 2A. illustrates a cross-sectional view of the tandem
solar cell structure in accordance with one embodiment of the
present application.
[0012] FIG. 2B illustrates a cross-sectional view of the tandem
solar cell structure in accordance with another embodiment of the
present application.
[0013] FIG. 3 illustrates the I-V curve of the alloy layer with
different concentration of Indium in the tunnel junction in
accordance with one embodiment of the present application.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Reference is made in detail to the preferred embodiments of
the present application, 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.
[0015] FIG. 2A illustrates a cross-sectional view of the tandem
solar cell structure in accordance with one embodiment of the
present application including a substrate 201, a buffer layer 202,
a first tunnel junction 203 and a first p-n junct on 204. The first
tunnel junction 203 includes a heavily doped n-type layer (n++)
2031 and an alloy layer 2032. In this application, the material of
the substrate 201 can be Silicon, Germanium, Si--Ge, GaAs or InP.
The material of the buffer layer 202, the heavily doped n-type
layer (n-F-F) 2031, the alloy layer 2032 and the first p-n junction
204 contains one or more elements selected from the group
consisting of (Gallium, Aluminum, indium, Arsenic, Phosphorous,
Nitrogen and Silicon, such as
(Al.sub.xGal.sub.1-x).sub.yIn.sub.1-yAs or (Al.sub.xGal.sub.1-x))
.sub.yIn.sub.1-yP.
[0016] The alloy layer 2032 comprises a heavily doped p-type layer
containing an element with atomic number larger than that of
Gallium. A p-type impurity with high. doping concentration and an
element with atomic number larger than that of Gallium are added in
the p-type layer in the epitaxial process to form the alloy layer
2032 having a heavily doped p-type layer with an element with
atomic number larger than that of Gallium. The lattice constant of
the alloy layer 2032 is increased b the content of the added
element with atomic number larger than that of Gallium to decrease
the lattice mismatch of the alloy layer 2032 and the substrate 201
so the quality of the epitaxial layers improved. Besides, the
energy gap of the alloy layer 2032 is decreased by adding the
element with atomic number larger than that of Gallium. The Jp
(current density), and the Jp/Vp (slope of current density to
voltage) of the alloy layer are increased and the tunneling current
of the first tunnel junction 203 is increased. The material of the
element with atomic number larger than that of Gallium can be
selected from Indium, Thallium, Antimony, Bismuth, Tin, Lead,
Bismuth, Polonium, Cadmium, and Mercury The concentration of the
element with atomic number larger than that of Gallium can be
1.about.2%, which is equal to
3.5.times.10.sup.21.about.1.7.times.10.sup.22 (1/cm.sup.3).
[0017] FIG. 2B illustrates a cross-sectional view of the tandem
solar cell structure in accordance with another embodiment of the
present application including a substrate 201, a buffer layer 202,
a first tunnel junction 203, a first p-n junction 204, a second
tunnel junction 205 and a second p-n junction 206. The first tunnel
junction 203 and the second tunnel junction 205 include heavily
doped n-type layers (n++) 2031, 2051 and alloy layers 2032,
2052.
[0018] In this application, the material of the substrate 201 can
be Silicon, Germanium, Si--Ge, GaAs or InP. The material of the
buffer layer 202, the heavily doped n-type layers (n++) 2031, 2051,
the alloy layers 2032, 2052, the first p-n junction 204 and the
second p-n junction 206 contains one or more elements selected from
the group consisting of Gallium, Aluminum, Indium, Arsenic,
Phosphorous, Nitrogen and Silicon, such as
(Al.sub.xGal.sub.1-x).sub.yIn.sub.1-yAs or
(Al.sub.xGal.sub.1-x).sub.yIn.sub.1-yP
[0019] The alloy layers 2032, 2052 comprise a heavily doped p-type
layer containing an element with atomic number larger than that of
Gallium. A p-type impurity with high doping concentration and an
element with atomic number larger than that of Gallium are added in
the p-type layer in the epitaxial process to form the alloy layer
2032, 2052 having a heavily doped p-type layer with an element with
atomic number larger than that of Gallium. The lattice constant of
the alloy layers 2032, 2052 is increased by the content of the
added element with atomic number larger than that of Gallium to
decrease the lattice mismatch of the alloy layers 2032, 2052 and
the substrate 201 so the quality of the epitaxial layers is
improved. Besides, the energy gap of the alloy layers 2032, 2052 is
decreased by adding the element with atomic number larger than that
of Gallium. The Jp (current density), and the Jp/Vp (slope of
current density to voltage) of the alloy layers are increased and
the tunneling current of the first tunnel junction 203 is also
increased. The material of the element with atomic number larger
than that of Gallium can be selected from Indium, Thallium,
Antimony, Bismuth, Tin, Lead, Bismuth, Polonium, Cadmium, and
Mercury. The concentration of the element with atomic number larger
than that of Gallium can be 1.about.2%, which is equal to
3.5.times.10.sup.21.about.1.7.times.10.sup.22 (1/cm.sup.3).
[0020] In one embodiment, the material of the substrate 201 is
Germanium. The material of the heavily doped n-type layers (n++)
2031, 2051 of the first and the second tunnel junction 203, 205 is
InGaP:Te. The material of the alloy layer 2032 2052 is
Al.sub.xGa.sub.(1-x)As: C + and is doped with In to form the
In.sub.yAl.sub.xGa.sub.(1-x)As alloy. The alloy layer can decrease
the lattice mismatch and increase the tunneling current of the
tunnel junction.
[0021] FIG. 3 illustrates the I-V curve of the alloy layer with
different concentration of Indium in the tunnel junction in
accordance with one embodiment of the present application. By
increasing the adding concentration of Indium, the slope of the I-V
curve is increased and the tunnel current through the first and the
second tunnel junction 203, 205 is also increased.
[0022] In other embodiment of this application, a third tunnel
junction can be formed on the second p-n junction 206 and a third
p-n junction can be formed on the third tunnel junction. The tunnel
junctions and the p-n junctions can be stacked repetitively based
on the requirement of the product and there is no need to limit the
number of the p-n junction in the tandem solar cell. The design of
the tunnel junction is substantially the same as the embodiment
mentioned above and can be referred thereto.
[0023] Although the drawings and the illustrations above are
corresponding to the specific embodiments individually, the
element, the practicing method, the designing principle, and the
technical theory can be referred, exchanged, incorporated,
collocated, coordinated except they are conflicted, incompatible,
or hard to be put into practice together.
[0024] Although the present application has been explained above,
it is not the limitation of the range, the sequence in practice,
the material in practice, the method in practice. Any modification
or decoration for present application is not detached from the
spirit and the range of such.
* * * * *