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用超高真空中对样品进行闪烁加热的方法,测量了Si(100)清洁表面吸附氢以后的热脱附谱。得到在室温下暴露氢时,低暴露量下只有一个脱附峰A,暴露量增大后,出现第二个脱附峰B。升高温度暴露氢,如在230℃以上暴露,热脱附谱中不出现B峰;在530℃以上暴露,则A,B峰均不出现。在室温下吸附氢后再加热退火,温度超过350℃,则热脱附谱中B峰不再存在;在530℃退火,则A峰也消失。热脱附的这些规律,使我们相信A峰和B峰分别对应于Si(100)表面的单氢化相和双氢化相的脱附。测量了它们的脱附活化能分别为52.9kcal/mol和14.5kcal/mol。从级数图证实了A峰的脱附属于一级脱附,但其机理并不与一般的一级或二级脱附机理相同。
Thermal desorption spectra of Si (100) -based clean surfaces after hydrogen adsorption were measured by flash heating samples in ultra-high vacuum. When exposed to hydrogen at room temperature, there was only one desorption peak A at a low exposure and a second desorption peak B after the exposure was increased. If hydrogen is exposed at an elevated temperature, no peak B appears in the thermal desorption spectrum when exposed at a temperature above 230 ° C. When the temperature is above 530 ° C, no peak A or B appears. Hydrogen adsorption at room temperature and then heated annealing, the temperature exceeds 350 ℃, the thermal desorption spectrum B peak no longer exists; at 530 ℃ annealing, the peak A disappears. These laws of thermal desorption lead us to believe that the A and B peaks correspond to the desorption of the monohydrogenated and dihydrogenated phases on the Si (100) surface, respectively. Their desorption activation energies were measured as 52.9 kcal / mol and 14.5 kcal / mol, respectively. It is confirmed from the series diagram that the desorption of peak A belongs to the first stage desorption, but the mechanism is not the same as that of the general primary or secondary desorption mechanism.