InGaP / GaAs Epi Wafer for Solar Cell

InGaP / GaAs Epi Wafer for Solar Cell

Thanks to GaAs tunnel junction technology, we offer epi wafers of single-junction and dual-junction InGaP / GaAs solar cells, with different structures of epitaxial layers (AlGaAs, InGaP) grown on GaAs for solar cell application. And now we offer GaAs epi wafer with InGaP tunnel junction as follows:

InGaP / GaAs Epi Wafer

1. InGaP / GaAs Solar Cell Epi-Structure

AR coating MgF2/ZnS Au Front contact
n+-GaAs 0.3μm
n+-AlInP <2×1018cm-3(Si) Window
InGaP n+-InGaP n
(Eg=1.88eV) p+-InGaP p
top cell p+-InGaP p+
           p+-AlInP BSF,diff.barrier
Tunnel p+-InGaP 0.015μm TN(p+)
junction n+-InGaP TN(n+)
            n+-AlInP 0.05μm Window,diff.barrier
GaAs  (Eg=1.43 eV)  bottom cell n+-GaAs n
p -GaAs p
            p+-InGaP BSF
p+-GaAs 7.0×1018cm-3(Zn)
p+-GaAs substrate       <1.0×1019cm-3(Zn) substrate
Back contact

LEDs, LASERs and InGaP / GaAs-based multi-junction Solar Cells can all employ tunnel junctions to improve performance. Calculating the effects of this junction is tricky, but there are ways to accurately simulate chip characteristics and cost-effectively optimize the design of solar cell structure.

2. Epitaxial Growth of InGaP / GaAs Solar Cell Wafer

With the development of MOCVD and MBE equipment, InGaP / GaAs dual junction solar cell can be grown on GaAs substrates with lattice matching, ensuring the crystal quality of epitaxial thin film. The subcell can use InAIP and AlGaAs materials as the window layer and back field layer, which can effectively reduce the surface and interface recombination speed. Under the condition of certain composition, the band gap of InGaP can be changed between 1.82eV and 1.92eV by adjusting the parameters such as growth temperature and growth rate, depending on the order degree of the crystal structure.

Combined with the design of the thickness of the absorber layer, the photogenerated currents generated by the InGaP and GaAs two-junction sub-cells can be better matched. On the basis of these factors, InGaP/GaAs double junction solar cells have high conversion efficiency. High-efficiency InGaP / GaAs thin-film solar cells can be prepared by substrate transfer technology.

When the GaInP / GaAs dual junction solar cell epitaxial material is grown by low-pressure growth technology, the pressure of the reaction chamber should be maintained at 42torr, and high-purity H2 is used as the carrier gas. The growth of the double-junction solar cell material was started at a constant temperature of 650 °C for 4 minutes. The growth temperature of arsenide and phosphide is both set at 620 °C, but the growth of the highly doped tunnel junction is prone to high temperature diffusion, so it is grown at a low temperature of 560 °C.

3. FAQ about Epitaxial Wafer of InGaP / GaAs

Q: Can you tell us how to cut the solar cell epi of AlGaP/GaAs?

A: The AlGaP/GaAs epi wafer for solar cell can be cut by wafer scriber.

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