Effects of H-termination on Ge film growth on Si(111) surfaces by solid phase epitaxy

Abstract

We have investigated solid phase epitaxy (SPE) of Ge films on H-terminated Si(111) surfaces using scanning tunneling microscopy (STM). In order to clarify the influence of adsorbed H atoms on the initial growth of Ge SPE on Si(111) surfaces, sub-bilayer (BL)-thick Ge films on the H-terminated Si surfaces were grown. It has been found that Ge clusters are formed at room temperature and the cluster shape changes by the existence of H atoms at the Ge/Si interface due to the reduction of interaction between Ge and Si atoms. Moreover, H atoms at the Ge/Si interface suppress the progress of surface reconstruction of Ge films and the crystallization of Ge films occurs with the desorption of H atoms from the Ge/Si interface. Two-dimensional (2D) islands formed by SPE at 500°C contain twinned domains and have irregular shapes while triangular-shaped 2D-islands are formed in Ge epitaxial growth by molecular beam epitaxy (MBE). The irregular shapes observed in the SPE growth are considered to result from the small surface migration of Ge atoms during annealing.