Reduced Defect Density in Single-Crystalline-like GaAs thin Film on Flexible Metal Substrates by using Superlattice Structures

High quality epitaxial and single-crystalline-like GaAs thin films grown by metal-organic chemical vapor deposition (MOCVD) on ion-beam textured buffers on flexible metal substrates have been reported earlier. Here we report significant reduction in defect density of the GaAs films by employing several techniques such as elevated temperature annealing/thermal cycling, low temperature GaAs growth and insertion of single In
l-x
Ga
x
As, In
l-x
Ga
x
As/GaAs superlattice (SL) structures. The GaAs films were thoroughly investigated by transmission electron microscopy (TEM). Further, the flexible GaAs films were used to grow single-junction GaAs solar cells which exhibited improved device performances with efficiencies reaching 5 % at AM1.5. The results show promise for low-cost, flexible, lightweight and high-performance III-V multijunction solar cells which can be a potentially game-changing technology in the photovoltaic market.