Aluminum arsenide eutectic gallium arsenide solar cell

• US 4,070,205 A
• Filed: 12/08/1976
• Issued: 01/24/1978
• Est. Priority Date: 12/08/1976
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Rahilly, William P.
• Primary Examiner(s): Mack, John H.
• Assistant Examiner(s): Weisstuch, Aaron
• Application Number:
  US05/748,578
• Time in Patent Office: 412 Days
• Field of Search: 136/89 SG, 136/89 SJ, 136/89 CC, 29/572, 357/30, 357/90, 357/91, 148/1.5, 148/171
• US Class Current: 136/255
• CPC Class Codes: H01L 31/03529 Shape of the potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/047 PV cell arrays including PV cells having multiple vertical junctions or multiple V-groove junctions formed in a semiconductor substrate
• CPC Class Codes: H01L 31/1844 comprising ternary or quaternary compounds, e.g. Ga Al As, In Ga As P
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials
• CPC Class Codes: Y10S 148/046 Electron beam treatment of devices
• CPC Class Codes: Y10S 148/084 Ion implantation of compound devices
• CPC Class Codes: Y10S 438/929 Eutectic semiconductor
• CPC Class Codes: Y10S 438/965 Shaped junction formation

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_x AsGa_l-x on the surface of the vertical PN junction substrate. The deposited GaAs layer with P dopant and the Al_x AsGa_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.

Claims

1. 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⁺ N junctions perpendicular to said vertical PN junctions;

c. a second liquid phase epitaxial growth region providing an Al_x AsGa_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.

2. 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_x AsGa_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_x AsGa_1-x ; and

f. metallizing a contact on the said N+ region.