Comparison of InGaSb/InAs superlattice structures grown by MBE on GaSb, GaAs, and compliant GaAs substrates

This paper contains the characterization results for indium arsenide/indium gallium antimonide (InAs/lnGaSb) superlattices (SL) that were grown by mol ecular beam epitaxy (MBE) on standard gallium arsenide (GaAs), standard GaS b, and compliant GaAs substrates. The atomic force microscopy (AFM) images, peak to valley (P-V) measurement, and surface roughness (RMS) measurements are reported for each sample. For the 5 mu m x 5 mu m Images, the P-V heig ht and RMS measurements were 37 Angstrom and 17 Angstrom, 12 Angstrom and 2 Angstrom, and 10 Angstrom and 1.8 Angstrom for the standard GaAs, standard GaSb, and compliant GaAs respectively. The high resolution x-ray diffracti on (HRXRD) analysis found different 0(th) order SL peak to GaSb peak spacin gs for the structures grown on the different substrates. These peak separat ions are consistent with different residual strain states within the SL str uctures. Depending on the constants used to determine the relative shift of the valance and conduction bands as a function of strain for the individua l layers, the change in the InAs conduction band to InGaSb valance band spa cing could range from +7 meV to -41 meV for a lattice constant of 6.1532 An gstrom. The cutoff wavelength for the SL structure on the compliant GaAs, c ontrol GaSb, and control GaAs was 13.9 mu m, 11 mu m, and no significant re sponse, respectively. This difference in cutoff wavelength corresponds to a pproximately a -23 meV change in the optical gap of the SL on the compliant GaAs substrate compared to the same SL on the control GaSb substrate.