Low-energy ion bombardment of the Ge(001)-(2×1) surface produces surface point defects, which are detected and quantified using in situ reflection high-energy electron diffraction. Surface defect production rates are determined for a range of ion energies and ion masses. At low substrate temperatures (T≊−100 °C), copious production of surface defects is observed, with defect yields as high as 20–30 defects per ion for 500 eV Ar and Xe bombardment. The observed He surface defect yields exceed the surface yield predicted by binary collision simulations, indicating that defects created in the subsurface region migrate to the surface for these conditions. The observed surface defect yield is reduced at elevated substrate temperatures. Based on a simple model this reduction is attributed to surface recombination of point defects created within the same cascade. A constant surface defect yield is reached at temperatures greater than 100 °C which is consistent with the net defect production due to the vacancies left by sputtering. However, even at elevated temperatures, significantly larger populations of mobile point defects than can be accounted for by sputtering may reside transiently on the surface, which can modify the overall surface morphology.

No abstract

We have measured surface roughening kinetics during low energy Xe ion sputtering of Ge (001) surfaces. The results are interpreted in terms of an instability theory developed by Bradley and Harper [l]. Although the calculated magnitude of the roughening rate does not agree with the measured value, the variation of the rate with ion flux and energy is in agreement with the theory.

No abstract

The adsorption and desorption kinetics of diethylsilane (DES) and diethylgermane (DEG) on a Ge(100) (2×1) surface have been studied using temperature-programmed desorption (TPD), Auger electron spectroscopy (AES), and high-resolution electron energy-loss spectroscopy. DES and DEG adsorb at room temperature in a self-limiting fashion. Data indicate that both precursors dissociatively chemisorb, producing a hydrogen- and ethyl-terminated surface. TPD of DES-saturated and DEG-saturated surfaces revealed only two desorbing species, ethylene and hydrogen. The ethylene signal results from the decomposition of the ethyl groups via β-hydride elimination, with a desorption peak temperature of ∼616 K for both precursors. The hydrogen TPD spectra were also similar for both precursors and consisted of two peaks: a low-temperature peak corresponding to hydrogen desorption from the monohydride state and a high-temperature peak corresponding to desorption of hydrogen produced by β-hydride elimination of the ethyl groups. Using the total hydrogen TPD peak area, DES saturation exposure (30 langmuir) led to 0.42 ML Si atom coverage and DEG saturation exposure (30 langmuir) led to 0.35 ML Ge atom coverage, assuming complete β-hydride elimination of the ethyl groups. 0.44 ML of Si was measured by AES following saturation DES exposure. No carbon contamination of the Ge surface was detected by AES for up to four exposure and TPD cycles of either DES or DEG.