The authors report an enhanced infrared spectral response of GaAs-based solar cells that incorporate type II GaSb quantum dots ͑QDs͒ formed using interfacial misfit array growth mode. The material and devices, grown by molecular beam epitaxy, are characterized by current-voltage and spectral response characteristics. From 0.9 to 1.36 m, these solar cells show significantly more infrared response compared to reference GaAs cells and previously reported InAs QD solar cells. The short circuit current density and open circuit voltages of solar cells with and without dots measured under identical conditions are 1.29 mA/ cm 2 , 0.37 V and 1.17 mA/ cm 2 , 0.6 V, respectively.
We report and characterize the growth of defect-free AlSb bulk material on Si (001) substrates using a monolithic self-assembled AlSb quantum dot (QD) nucleation layer. During the first few monolayers of AlSb growth on Si, highly crystalline QDs form. With continued deposition, the islands coalesce into a planar material with no detectable defects. The QD nucleation layer facilitates a completely relaxed AlSb within ∼100 ML of deposition according to x-ray diffraction. We attribute the success of AlSb growth on Si to both the large AlSb∕Si lattice mismatch (Δa0∕a0=13.5%) in combination with the strong AlSb atomic bond. We also demonstrate room temperature photoluminescence from an InGaSb QW grown on the AlSb bulk layer.
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