Lattice constant grading in the Al[sub y]Ga[sub 1[minus]y]As[sub 1[minus]x]Sb[sub x] alloy system
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 growing layer. 3 figs.
- Assignee:
- Varian Associates, Inc., Palo Alto, CA (United States)
- Patent Number(s):
- US 4195305; A
- Application Number:
- PPN: US 5-945653
- OSTI ID:
- 7247759
- Country of Publication:
- United States
- Language:
- English
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