A MOLECULAR-BEAM STUDY OF DESORPTION-KINETICS OF GEO FROM GE(111) SURFACES

The desorption kinetics of GeO, formed in the reaction of O2 and NO with Ge(111) surfaces at temperatures between 800 and 1000 K, has been investigated by a pulsed molecular beam technique. The gaseous GeO product was detected above 750 k, using a mass spectrometer set to m/e = 90. The waveform of the signal intensity changed with surface temperature. The relaxation waveforms were analyzed by computer simulation, and it was found that all waveforms obtained in the experimental temperature range were well fitted with the curves synthesized from a gate function and a decay curve with a single exponential term, exp(-kt). The rate constants were obtained as follows: k = (10(15.2+/-0.4) s-1)exp(-2.0 +/- 0.1 eV/k(B)T), for O2, and k = (10(15.4+/-0.7) s-1) exp(-2.0 +/- 0.2 eV/k(B)T), for NO. The reaction probability for each O atom in O2 was about 1%, and that for NO was about half of this.