Growth of abrupt GaAs/Ge heterointerfaces by atomic hydrogen-assisted molecular beam epitaxy

High-quality epitaxy of GaAs-on-Ge system has been developed at low growth temperatures around 400 degrees C by atomic hydrogen-assisted molecular beam epitaxy (H-MBE). The segregation of Ge is significantly reduced and abrupt GaAs/Ge heterointerface is successfully formed. Using reflection high-energy electron diffraction (RHEED), secondary ion mass spectroscopy (SIMS) and atomic force microscopy (AFM) as characterization tools, it is demonstrated that enhanced layer-by-layer two-dimensional growth mode is realized from the earliest stages of growth and evolution of single domain (2 x 4) GaAs (0 0 1) is achieved on vicinal Ge substrates at 400 degrees C by H-MBE technique. The modification of growth mode and consequent improvement in material quality are explained at the simplest level by the surfactant properties of atomic H in MBE growth of GaAs.