Modification of H-terminated Ge surface in hydrochloric acid

Various amounts of H-termination on a Ge surface were prepared by dipping a Ge wafer in differentially diluted hydrofluoric acid solutions for different periods of time. Formation of GeHx in hydrofluoric acid and its disappearance in hydrochloric acid (HCl) were directly measured by using multiple internal reflection Fourier transform infrared spectroscopy (MIR FT-IR). Peak intensity of GeHx vibration mode was increased with diluted hydrofluoric acid (DHF) treatment time and the concentration of HF solution. Therefore, it is suggested that microroughness of a Ge surface changes depending on the concentration of HF. Peak intensity of GeHx vibration mode was reduced when the GeHx surface was treated in HCl solution. With an increase in HCl treatment time, peak intensity of GeHx vibration mode was reduced. Ge surfaces treated in a more diluted HF solution were barely modified, because it was thought to have fewer kink sites, dihydrides and trihydrides.