Aluminum arsenide eutectic gallium arsenide solar cell
AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorWilliam P. Rahilly
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Abstract
An improved gallium arsenide solar cell is provided by forming a P+ layer on top of a wafer of plural vertical PN junction eutectic gallium arsenide crystal by liquid phase epitaxial growth of P doped GaAs followed by liquid phase epitaxial growth at Al.sub.x AsGa.sub.l-x on the surface of the vertical PN junction substrate. The deposited GaAs layer with P dopant and the Al.sub.x AsGa.sub.l-x layer forms horizontal P-N junctions with the N-type vertical regions. An N+ region is formed on the solar cell backside by ion implantation of an N dopant followed by a pulse electron beam current of the implanted region.
Claims2
A solar cell comprising:
- a. a wafer formed of a crystal of eutectic gallium arsenide having a plurality of alternating P and N doped regions forming a plurality of vertical PN junctions between a top and a bottom surface thereof;
- b. a first liquid phase epitaxial growth region overlying the said upper surface providing a GaAS P+ region adjacent the said upper surface thereby forming substantially horizontal P.sup.+ N junctions perpendicular to said vertical PN junctions;
- c. a second liquid phase epitaxial growth region providing an Al.sub.x AsGa.sub.1-x P+ region overlying the said GaAs P+ region, and providing an operating surface;
- d. an N+ region formed by ion implantation into the said bottom surface;
- e. a metallization contact positioned on the said operating surface;
- and
- f. a metallization contact positioned on the said bottom surface.
The method of forming a solar cell on a wafer of eutectic gallium arsenide substrate having a plurality of vertical PN junctions formed between an upper surface and a lower surface comprising the steps of:
- a. growing by liquid phase epitaxial deposition a layer of GaAs doped with a P type impurity to provide a P+ layer on the said upper surface of the said substrate;
- b. growing by liquid phase epitaxial deposition of a P+ doped Al.sub.x AsGa.sub.1-x layer on the said P doped GaAs layer;
- c. ion implanting an N type impurity on the said lower surface to provide a N+ region;
- d. annealing the said N+ region with a pulsed electron beam;
- e. metallizing a contact on the said Al.sub.x AsGa.sub.1-x ;
- and
- f. metallizing a contact on the said N+ region.
Dependencies are inferred from the claim text.