Tilt growth of MnAs on the GaAs(001) substrate

The complete strain tensor in the tilted-grown epilayer is studied based on the linear elastic theory. With the boundary constrain conditions, the tilt angle of an epilayer can be obtained from the minimization of the strain energy. In this way we can also describe the distortion of crystal cells in the epilayer. In this Letter, as an application of our theory, we focus on the growth of the MnAs epilayer on the GaAs(001) substrate. It is shown that the lattice mismatch strain between the MnAs epilayer and the GaAs substrate can be relaxed by two mechanisms. On the one hand, by forming the lattice coincidence construction at the interface, the type A growth can be realized. On the other hand, by tilting the epilayer by about 30° with respect to the substrate, the type B growth is favored. The competition between the two mechanisms is near an equilibrium for this specific system, and depending on the growth conditions, it may lead to either an A type growth or a B type growth. Our theoretical results agree well with the reported experimental observations.