Growth, characterization, and spin dynamics of AlSb/GaSb/InAs heterostructures in [100] and [110] orientations

Summary form only given. Molecular beam epitaxial growth on III-V substrates has been optimized for [100] oriented growth. However, spintronic devices may benefit from growth of quantum structures on [110] oriented substrates because the D´yakanov-Perel spin relaxation mechanism is suppressed or absent in this orientation for 2-D systems. Consistent with this hypothesis, we have recently measured a significant enhancement of the spin relaxation time in a [110]-oriented, short period, InAs/GaSb superlattice relative to a similar [001]-oriented structure. The spin dynamics were measured in the two superlattices using 100 fs mid-infrared pulses from a synchronously pumped PPLN optical parametric oscillator and polarization-sensitive, differential transmission. Results at /spl sim/120 K, indicate that the spin relaxation time in the [110] superlattice is twenty times longer than that measured for the [001] structure. We are currently investigating the growth and optimization of 6.1 /spl Aring/ heterostructures on InAs [110] and GaSb [110] oriented substrates. We have noted interesting differences in the growth behavior between the [100] and [110] orientations with respect to group V dependence and antimonide on arsenide terminated interfaces. In addition, the bandgap of corresponding InAs/GaSb superlattices are consistently observed at much lower energies on [110] versus [100] orientations. The origin of these differences will be discussed with reference to band structure calculations.