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U.S. Department of Energy
Office of Scientific and Technical Information

Lattice constant grading in the Al[sub y]Ga[sub 1[minus]y]As[sub 1[minus]x]Sb[sub x] alloy system

Patent ·
OSTI ID:7005366
Liquid phase epitaxy is employed to grow a lattice matched layer of GaAsSb on GaAs substrates through the compositional intermediary of the III-V alloy system AlGaAsSb which acts as a grading layer. The Al constituent reaches a peak atomic concentration of about 6% within the first 2.5[mu]m of the transition layer, then decreases smoothly to about 1% to obtain a lattice constant of 5.74 A. In the same interval the equilibrium concentration of Sb smoothly increases from 0 to about 9 atomic percent to form a surface on which a GaAsSb layer having the desired energy bandgap of 1.1 eV for one junction of an optimized dual junction photovoltaic device. The liquid phase epitaxy is accomplished with a step cooling procedure whereby dislocation defects are more uniformly distributed over the surface of the growing layer. 2 figs.
Assignee:
Varian Associates, Inc., Palo Alto, CA (United States)
Patent Number(s):
A; US 4246050
Application Number:
PPN: US 6-059705
OSTI ID:
7005366
Country of Publication:
United States
Language:
English