Summary of the invention
Technical problem to be solved by this invention is that three knot tandem solar cell and preparation method thereof are provided.
In order to address the above problem, the invention provides a kind of three knot tandem solar cell, the substrate that comprises GaAs or Ge, and the first gradual transition layer setting gradually on described substrate, the sub-battery of InGaAs, the second gradual transition layer, the first tunnel junction, the sub-battery of GaAs, the second tunnel junction, the sub-battery of GaInP and GaAs contact layer.
Between the sub-battery of the substrate of described GaAs or Ge and InGaAs, further comprise the 3rd tunnel junction, described the 3rd tunnel junction comprises successively GaInP or GaAs layer, (Al) GaAs layer and the 3rd barrier layer arranging away from substrate direction according to gradually, and described the 3rd barrier layer is AlGaAs or Al (Ga) InP.
The material of described the first gradual transition layer and the second gradual transition layer is Al
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xas, the scope of the first gradual transition layer x is that 0 to 0.27, y scope is 0 to 0.4; The scope of the x of the second gradual transition layer is that 0.27 to 0, y scope is 0.4 to 0.The band gap of described the second gradual transition layer is greater than the band gap of the sub-battery of GaAs.
The sub-power brick of described InGaAs containing successively according to the first back surface field layer, the first base of InGaAs, the first emitter region of InGaAs and the first window layer that are AlGaInAs away from the material of the direction setting of substrate gradually, the material of described first window layer be in GaInP, InGaAlAs and AlInP any one.
Described the first tunnel junction comprises successively GaInP or GaAs layer, (Al) GaAs layer and the first barrier layer arranging away from the direction of substrate according to gradually, and the material of described the first barrier layer is AlGaAs or Al (Ga) InP.
The sub-power brick of described GaAs is containing successively according to the Second Window layer of the second back surface field layer, the second base of GaAs, the second emitter region of GaAs and Al (Ga) InP that are GaInP away from the material of the direction setting of substrate gradually.
Described the second tunnel junction comprises successively according to the GaInP arranging away from the direction of substrate gradually or GaAs layer and (Al) GaAs layer.
The sub-power brick of described GaInP is containing being that the 3rd back surface field layer of Al (Ga) InP is, the 3rd emitter region of the 3rd base of GaInP, GaInP and the 3rd Window layer of AlInP according to the material away from the direction setting of substrate gradually successively.
For solving the problems of the technologies described above, the present invention also provides a kind of preparation method of three knot tandem solar cell described above, and step is on substrate, grow successively the first gradual transition layer, the sub-battery of InGaAs, the second gradual transition layer, the first tunnel junction, the sub-battery of GaAs, the second tunnel junction and the sub-battery of GaInP and GaAs contact layer.
Before the step of described Grown the first gradual transition layer, further comprise step: at described Grown the 3rd tunnel junction, described the 3rd tunnel junction comprises successively according to the GaInP arranging away from substrate direction gradually or GaAs layer, (Al) GaAs layer, the 3rd barrier layer, and the material of described the 3rd barrier layer is AlGaAs or Al (Ga) InP.
The invention provides three knot tandem solar cell and preparation method thereof, advantage is:
1. the sub-battery band gap of the sub-battery of InGaAs, the sub-battery of GaAs and GaInP in this three knots tandem solar cell combines be respectively ~ 1.00 eV, 1.42 eV, 1.90 eV, the currents match of each sub-battery, reduce the heat-energy losses in photoelectric conversion process, improved battery efficiency;
2. this three knots tandem solar cell adopts the growth of formal dress growing method, element manufacturing and standard cell process compatible, avoided being inverted the complicated technology that growth battery structure needs first to remove with other support substrates material bonding GaAs or Ge substrate again, reduced the manufacture difficulty of battery;
3. this three knots tandem solar cell is passed through to select applicable gradual transition layer material, thereby overcomes the mismatch between GaAs and InGaAs.
Embodiment
Below in conjunction with accompanying drawing, the embodiment of three knot tandem solar cell provided by the invention and preparation method thereof is elaborated.
The first embodiment
Figure 1 shows that the structural representation of the first embodiment of three knot tandem solar cell of the present invention.
Present embodiment provides a kind of GaInP/GaAs/InGaAs tri-knot tandem solar cell based on the growth of lattice mutation method, comprise substrate 26, and the sub-battery 02 of the first gradual transition layer 01, the InGaAs that set gradually on described substrate 26, the second gradual transition layer 03, the first tunnel junction 04, the sub-battery 05 of GaAs, the second tunnel junction 06, the sub-battery 07 of GaInP and GaAs contact layer 25.Between three sub-batteries, by tunnel junction, connect.
This three knots tandem solar cell adopts GaAs or Ge as substrate 26, in the mode of formal dress growth, grows.The sub-battery 02 of InGaAs of bottom is InGaAs single junction cell, with GaAs lattice mismatch; GaInP/GaAs binode battery and GaAs Lattice Matching that the sub-battery 05 of the sub-battery 07 of GaInP of top layer and GaAs forms.Mode by lattice mutation growth gradual transition layer between above-mentioned single junction cell and binode battery is cascaded.
Band gap combination be respectively ~ 1.00 eV, 1.42 eV and 1.90 eV of the sub-battery 02 of described InGaAs, the sub-battery 05 of GaAs and the sub-battery 07 of GaInP.
The first back surface field layer 08, the first base 09 of InGaAs, the first emitter region 10 and the first window layer 11 of InGaAs that it is AlGaInAs away from the material of the direction setting of substrate 26 that the sub-battery 02 of described InGaAs comprises successively according to gradually, the material of described first window layer 11 be in GaInP, InGaAlAs and AlInP any one;
Described the first tunnel junction 04 comprises successively GaInP or GaAs layer 12, (Al) GaAs layer 13 and the first barrier layer 14 arranging away from the direction of substrate 26 according to gradually, and the material of described the first barrier layer 14 is AlGaAs or Al (Ga) InP;
Wherein, (Al) GaAs occurring in the application is the meaning of AlGaAs or GaAs; The Al occurring in the application (Ga) InP is the meaning of AlInP or AlGaInP.
The sub-battery 05 of described GaAs comprises successively according to the Second Window layer 18 of the second back surface field layer 15, the second base 16 of GaAs, the second emitter region 17 of GaAs and Al (Ga) InP that are GaInP away from the material of the direction setting of substrate 26 gradually;
Described the second tunnel junction 06 comprises successively according to the GaInP arranging away from the direction of substrate 26 gradually or GaAs layer 19, (Al) GaAs layer 20;
It is that the 3rd back surface field layer 21 of Al (Ga) InP is, the 3rd emitter region 23 of the 3rd base 22 of GaInP, GaInP and the 3rd Window layer 24 of AlInP that the sub-battery 07 of described GaInP comprises successively according to the material away from the direction setting of substrate 26 gradually.
Described the first gradual transition layer 01 and the second gradual transition layer 03 are Al
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xas, in the first gradual transition layer 01, the scope of x is that 0 to 0.27, y scope is 0 to 0.4; In the second gradual transition layer 03, the scope of x is that 0.27 to 0, y scope is 0.4 to 0.The band gap of described the second gradual transition layer 03 is greater than the band gap of the sub-battery of GaAs, i.e. 1.42eV.
As optional execution mode, between the sub-battery 02 of the substrate 26 of described GaAs or Ge and InGaAs, further comprise the 3rd tunnel junction, described the 3rd tunnel junction comprises successively GaInP or GaAs layer, (Al) GaAs layer and the 3rd barrier layer arranging away from substrate 26 directions according to gradually, and described the 3rd barrier layer is AlGaAs or Al (Ga) InP.
As optional execution mode, in the sub-battery 05 of described GaAs, material is the Second Window layer 18 of Al (Ga) InP, also can be used as the barrier layer of the second tunnel junctions 06.
As optional execution mode, in the sub-battery 07 of described GaInP, material is the 3rd back surface field layer 21 of Al (Ga) InP, also can be used as the barrier layer of the second tunnel junctions 06.
Figure 2 shows that the product structure schematic diagram of three knot tandem solar cell the first specific embodiments of the present invention.
As Fig. 2, the product of described GaInP/GaAs/InGaAs tri-knot tandem solar cell, for further comprise top electrode 28, bottom electrode 27 on the architecture basics of Fig. 1, lays respectively on the exposed surface of contact layer 25 and on the exposed surface of substrate 26.
The second embodiment
Present embodiment provides a kind of growth preparation method of GaInP/GaAs/InGaAs described in Figure 1 tri-knot tandem solar cell, adopts formal dress growth pattern on described substrate 26, grow successively the first gradual transition layer 01, the sub-battery 02 of InGaAs, the second gradual transition layer 03, the first tunnel junction 04, the sub-battery 05 of GaAs, the second tunnel junction 06, the sub-battery 07 of GaInP and GaAs contact layer 25.Between three sub-batteries, by tunnel junction, connect.
The preparation method of above-mentioned three knot tandem solar cell, further comprises the preparation process of preparing top electrode 28, bottom electrode 27, and the preparation process of described top electrode 28 for directly preparing top electrode 28 on the exposed surface of described GaAs contact layer 25; The preparation process of described bottom electrode 27 is for adopting preparing bottom electrode 27 on the exposed surface of described substrate 26.
In present embodiment, adopt lattice mutation growth Al
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xthe method of the first gradual transition layer 01 of As discharges stress, realization is by the transition of substrate 26 to the InGaAs batteries 02 of GaAs or Ge, wherein the value of x is changed to 0.4 by 0 value that is changed to 0.27, y by 0, realizes GaAs lattice constant to the transition of InGaAs lattice constant; Overcome the mismatch between the sub-battery 02 of GaAs or Ge substrate 26 and InGaAs.
In present embodiment, adopt lattice mutation growth Al
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xthe method of the second gradual transition layer 03 of As discharges stress, realizes the transition by sub-battery 02 to the GaAs battery 05 of InGaAs, and the value of x is changed to 0 by 0.4, this Al by 0.27 value that is changed to 0, y again
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xthe band gap of the second gradual transition layer 03 of As is greater than the band gap of the sub-battery of GaAs, i.e. 1.42 eV can not absorb the spectrum of the sub-battery 02 of InGaAs, have overcome the mismatch between the sub-battery 05 of GaAs and the sub-battery 02 of InGaAs.
As optional execution mode, material is Al
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xthe first gradual transition layer 01 of As and the second gradual transition layer 03 all can adopt the method growth of In component and Al component linear progression, make Stress Release.
As optional execution mode, material is Al
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xthe first gradual transition layer 01 of As and the second gradual transition layer 03 all can adopt the method growth of In component and the stepping of Al component, by forming a plurality of interfaces, promote Stress Release to suppress threading dislocation arrival active area simultaneously.
As optional execution mode, material is Al
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xthe first gradual transition layer 01 of As all can adopt the method growth that In component and Al component linear progression and stepping combine to make Stress Release with the second gradual transition layer 03, suppresses threading dislocation and arrives active area.
As optional execution mode, Al first grows between the sub-battery 02 of InGaAs and the sub-battery 05 of GaAs
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xthe second gradual transition layer 03 of As, first tunnel junction 04 of then growing.
As optional execution mode, adopt the GaInP/GaAs/InGaAs tri-knot tandem solar cell of lattice mutation method growth to select the GaAs of P type or Ge as substrate 26.First growing P-type Al on the substrate 26 of P type GaAs or Ge
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xthe first gradual transition layer 01 of As, utilizes the first gradual transition layer 01 GaAs lattice constant to be transitioned into the lattice constant of the sub-battery 02 of InGaAs, so that the sub-battery 02 of growth InGaAs; Then adopt N-type Al
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xthe second gradual transition layer 03 of As is transitioned into the lattice constant of InGaAs the lattice constant of the sub-battery 05 of GaAs, so that the sub-battery 05 of growth GaAs and the sub-battery 07 of GaInP are connected by tunnel junction between each sub-battery.
As optional execution mode, adopt the GaInP/GaAs/InGaAs tri-knot tandem solar cell of lattice mutation method growth to select the GaAs of N-type or Ge as substrate 26, before the step of the first gradual transition layer 01 of growing on described substrate 26, further comprise step: growth regulation three tunnel junctions on described substrate 26, described the 3rd tunnel junction comprises successively according to the GaInP of the N-type arranging away from substrate 26 directions gradually or GaAs layer, (Al) GaAs layer of P type, the 3rd barrier layer of P type, and described the 3rd barrier layer material is AlGaAs or Al (Ga) InP.
As optional execution mode, all described growths all adopt mocvd method, the foreign atom of described N-type doping be in Si, Se, S and Te any one, the foreign atom of described P type doping be in Zn, Mg and C any one.
As optional execution mode, all described growths all adopt MBE method growth, the foreign atom of described N-type doping be in Si, Se, S, Sn and Te any one, the foreign atom of described P type doping be in Be, Mg and C any one.
Next provide several embodiments of the present invention.
Embodiment mono-
In the present embodiment, provide a kind of preparation method of GaInP/GaAs/InGaAs tri-knot cascade solar cells of lattice mutation growing method growth, comprise the following steps:
(1) adopt MOCVD(Metal Organic Chemical Vapor Deposition, metallo-organic compound chemical gaseous phase deposition) method growth GaInP/GaAs/InGaAs tri-knot cascade solar cells, its structure as shown in Figure 1:
(1) growing P-type doping 4 * 10 on the substrate 26 of P type GaAs or Ge
17cm
-3the Al of 2.6 microns
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xthe first gradual transition layer 01 of As, to realize GaAs lattice constant to the transition of InGaAs lattice constant;
(2) at Al
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xgrowing P-type doping content approximately 1 * 10 on the first gradual transition layer 01 of As
18cm
-3the AlGaInAs 08 of 0.1 micron as the first back surface field layer 08 of the sub-battery 02 of InGaAs, then growing P-type doping content approximately 3 * 10 on the first back surface field layer 08
17cm
-3the InGaAs of 3.0 microns as the first base 09 of the sub-battery 02 of InGaAs, then the N-type doping content approximately 2 * 10 of growing on the first base 09
18cm
-3the InGaAs of 0.2 micron as the first emitter region 10 of the sub-battery 02 of InGaAs, the highly doped AlGaInAs of 0.05 micron of the N-type of then growing on the first emitter region 10 or GaInP or AlInP are as the first window layer 11 of the sub-battery 02 of InGaAs;
(3) the N-type doping content approximately 4 * 10 of growing on the sub-battery 02 of InGaAs
17cm
-3the Al of 2.6 microns
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xthe second gradual transition layer 03 of As, to realize InGaAs lattice constant to the transition of GaAs lattice constant;
(4) the N-type doping content of growing on the second gradual transition layer 03 is greater than 1 * 10
19cm
-3the GaInP of 0.02 micron or GaAs layer 12, then on GaInP or GaAs layer 12, growing P-type doping content is greater than 1 * 10
19cm
-3(Al) GaAs layer 13 of 0.02 micron, then on (Al) GaAs layer 13 growing P-type doping content approximately 1 * 10
18cm
-3the AlGaAs of 0.05 micron or Al (Ga) InP as the first barrier layer 14 of tunnel junction P type layer, form the first tunnel junction 04;
(5) growing P-type doping content approximately 2 * 10 on the first tunnel junction 04
18cm
-3the GaInP layer of 0.05 micron as the second back surface field layer 15 of the sub-battery 05 of GaAs, prevent that light induced electron from spreading downwards; On the second back surface field layer 15, growing P-type doping content approximately 1 * 10
17cm
-3the GaAs layer of 2.8 microns as the second base 16 of the sub-battery 05 of GaAs, the N-type doping content approximately 2 * 10 of then growing on the second base 16
18cm
-3the GaAs layer of 0.15 micron as the second emitter region 17 of the sub-battery 05 of GaAs;
(6) on the second emitter region 17, grow highly doped Al (Ga) InP of 0.05 micron of one deck N-type as the Second Window layer 18 of the sub-battery 05 of GaAs, to reduce the compound of photo-generated carrier, also can be used as the barrier layer of the N-type layer of the second tunnel junctions 06;
(7) the N-type doping content of growing on the sub-battery 05 of GaAs is greater than 1 * 10
19cm
-3the GaInP of 0.015 micron or GaAs layer 19, on GaInP or GaAs layer 19, growing P-type doping content is greater than 1 * 10
19cm
-3(Al) GaAs layer 20 of 0.015 micron, growing P-type doping content approximately 1 * 10 on (Al) GaAs layer 20 then
18cm
-3al (Ga) InP of 0.05 micron as the barrier layer 21 of tunnel junction P type layer, form the second tunnel junction 06, also can be used as the 3rd back surface field layer 21 of the sub-battery 07 of GaInP;
(8) on the second tunnel junction 06, growing P-type doping content is about 1 * 10
17cm
-3the GaInP of 0.5 micron as the 3rd base 22 of the sub-battery 07 of GaInP, the N-type doping content of then growing on the 3rd base 22 is about 2 * 10
18cm
-3the GaInP of 0.2 micron as the 3rd emitter region 23 of the sub-battery 07 of GaInP;
(9) on the 3rd emitter region 23, grow the highly doped AlInP of 0.02 micron of N-type as the 3rd Window layer 24 of GaInP 07 battery, the N-type doping content of then growing in the 3rd Window layer 24 is about 6 * 10
18cm
-3the GaAs of 0.5 micron as the GaAs contact layer 25 of the sub-battery 07 of GaInP, for realizing ohmic contact layer.
(2) technology for preparing electrode
(10) on N-type GaAs contact layer 25 and on the substrate 26 of P type GaAs or Ge, prepare respectively top electrode 28, bottom electrode 27, described top electrode 28 is N-type electrode, bottom electrode 27 is P type electrode, obtains the product of required solar cell, and its product structure as shown in Figure 2.
In the present embodiment, the foreign atom of N-type doping be in Si, Se, S and Te any one, the foreign atom of described P type doping be in Zn, Mg and C any one.
Embodiment bis-
Figure 3 shows that the structural representation of described three knot tandem solar cell embodiment bis-.
The present embodiment provides a kind of GaInP/GaAs/InGaAs tri-knot tandem solar cell, its structure is on the basis of three knot tandem solar cell structures in Fig. 1, between the substrate 26 of described GaAs or Ge and the first gradual transition layer 01, increase by the 3rd tunnel junction 29, described the 3rd tunnel junction 29 is identical with the structure of the first tunnel junction 04 in Fig. 1, comprise successively according to the GaInP arranging away from substrate 26 directions gradually or GaAs layer 30, (Al) GaAs layer 31, the 3rd barrier layer 32, described the 3rd barrier layer 32 is AlGaAs or Al (Ga) InP.
The present embodiment also provides a kind of preparation method of GaInP/GaAs/InGaAs tri-knot cascade solar cells, comprises following concrete steps:
(1) adopting MBE(Molecular Beam Epitaxy, molecular beam epitaxy) method carries out the growth of described GaInP/GaAs/InGaAs tri-knot tandem solar cell
(1) growth regulation three tunnel junctions 29 on the substrate 26 of N-type GaAs or Ge;
(2) growing P-type Al on the 3rd tunnel junction 29
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xthe first gradual transition layer 01 of As;
(3) the sub-battery 02 of InGaAs of growing on the first gradual transition layer 01;
(4) the N-type Al that grows on the sub-battery 02 of InGaAs
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xthe second gradual transition layer 03 of As, its band gap is greater than 1.42 eV;
(5) first tunnel junction 04 of growing on the second gradual transition layer 03, comprise along the N-type GaInP setting gradually away from the direction of the sub-battery 02 of InGaAs gradually or the heavily doped layer 12 of GaAs, the heavily doped layer 13 of P type (Al) GaAs and P type AlGaAs or Al (Ga) InP barrier layer 14;
(6) the sub-battery 05 of GaAs of growing on the first tunnel junction 04;
(7) second tunnel junction 06 of growing on the sub-battery 05 of GaAs, comprise N-type Al (Ga) the InP barrier layer 19 setting gradually away from the direction of the sub-battery 05 of GaAs along gradually, the heavily doped layer 20 of N-type GaInP or GaAs, the heavily doped layer of P type (Al) GaAs and P type Al (Ga) InP barrier layer 21;
(8) the sub-battery 07 of GaInP of growing on the second tunnel junction 06;
(9) on the sub-battery 07 of GaInP, grow N-type GaAs layer as GaAs contact layer 25, for realizing ohmic contact layer;
Fig. 4 is the product structure schematic diagram of described three knot tandem solar cell embodiment bis-.
(2) technology for preparing electrode
(10) on GaAs contact layer 25 and on GaAs or Ge substrate 26, prepare respectively top electrode 28 and bottom electrode 27, obtain required solar cell.
In the present embodiment, N-type foreign atom be in Si, Se, S, Sn and Te any one, P type foreign atom be in Be, Mg and C any one.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.