Although most theoretical calculations of quantum wells with non-square profiles assume that material composition is varied continuously, it is more common in experiment to grow digital alloys. We compare the Rashba spin-orbit interaction of triangul
ar wells using continuous, discrete, and digital alloying profiles in (001)-grown triangular InSb/Al_f(z)In_(1-f(z))Sb, finding a very large difference between digital alloying and the others, including a sign change in the Rashba spin-orbit coupling. We find that the interface contribution to the Rashba spin-orbit coupling is much larger in the continuously- and discretely-alloyed triangular quantum wells than in the digitally-alloyed triangular wells, in which it is almost completely absent. The electric field contribution, however, is quite similar in all three systems. Due to a much stronger doping dependence in all three systems, the electric field contribution dominates at higher dopings, although the very large offset due to the near absence of interface contribution in digitally-alloyed wells persists.
The effect of an electric field on spin precession in In0.5Ga0.5As/GaAs self-assembled quantum dots is calculated using multiband real-space envelope-function theory. The dependence of the Lande g tensor on electric fields should permit high-frequenc
y g tensor modulation resonance, as well as direct, nonresonant electric-field control of the hole spin. Subharmonic resonances have also been found in g tensor modulation resonance of the holes, due to the strong quadratic dependence of components of the hole g tensor on the electric field.
We predict it is possible to achieve high-efficiency room-temperature spin injection from a mag- netic metal into InAs-based semiconductors using an engineered Schottky barrier based on an InAs/AlSb superlattice. The Schottky barrier with most metals
is negative for InAs and positive for AlSb. For such metals there exist InAs/AlSb superlattices with a conduction band edge perfectly aligned with the metals Fermi energy. The initial AlSb layer can be grown to the thickness required to produce a desired interface resistance. We show that the conductivity and spin lifetimes of such superlattices are sufficiently high to permit efficient spin injection from ferromagnetic metals.
We calculate the dependence on an applied electric field of the g tensor of a single electron in a self-assembled InAs/GaAs quantum dot. We identify dot sizes and shapes for which one in-plane component of the g tensor changes sign for realistic elec
tric fields, and show this should permit full Bloch-sphere control of the electron spin in the quantum dot using only a static magnetic field and a single vertical electric gate.
