Structural properties of LT-GaAs(100) and GaMnAs(100) surfaces studied by scanning tunneling microscopy

In English GaAs and GaMnAs compounds grown by low temperature (LT) molecular beam epitaxy (MBE), are promising materials for fabricating novel devices. LT-GaAs has already been used in new devices, as it has subpicosecond carrier lifetimes, good carrier mobility and high dark resistivity. GaMnAs compounds are candidates for integrating ferromagnetic materials into semiconductor devices, as they can become ferromagnetic at around 110 K. We have studied the surface structure of As capped MBE grown LT-GaAs(100) and GaMnAs(100) surfaces as a function of annealing temperature by Scanning Tunneling Microscopy (STM). On LT-GaAs(100) we find an ordered 2×4 phase at 400 C and an ordered 4×6 phase at 600 C. These phases have some similarities with the phases found on ordinary GaAs (100). For GaMnAs (100) we identify a new 4×6 phase after annealing to 600 C, which is observed to be different in morphology and structure from the 4×6 ordered phases found on GaAs(100)