Semicoherent growth of Bi2Te3 layers on InP substrates by hot wall epitaxy

We search for optimum growth conditions to realize flat Bi2Te3 layers on InP(111) B by hot wall epitaxy. The substrate provides a relatively small lattice mismatch, and so (0001)-oriented layers grow semicoherently. The temperature window for the growth is found to be narrow due to the nonzero lattice mismatch and rapid re-evaporation of Bi2Te3. The crystalline qualities evaluated by means of x-ray diffraction reveal deteriorations when the substrate temperature deviates from the optimum not only to low temperatures but also to high temperatures. For high substrate temperatures, the Bi composition increases as Te is partially lost by sublimation. We show, in addition, that the exposure of the Bi2Te3 flux at even higher temperatures results in anisotropic etching of the substrates due, presumably, to the Bi substitution by the In atoms from the substrates. By growing Bi2Te3 layers on InP(001), we demonstrate that the bond anisotropy on the substrate surface gives rise to a reduction in the in-plane epitaxial alignment symmetry.