用HREELS研究氢在GaAs和InP的(111),(111)表面上的吸附

氢在GaAs和InP表面上的吸附可以用高分辨率电子能量损失谱(HREELS)来探测。Ga—H,As—H,In—H和P—H键的伸缩振动各自对应于不同的能量损失。但是As—H振动极容易和Ga—H振动追加声子损失相混淆,只有从损失峰的相对强度比较上来区别。实验得到吸附的氢与表面原子的成键情况取决于表面的原子结构及电子分布。对于GaAs(111)面,低暴露量时只形成Ga—H键,而高暴露量时还可以形成As—H键。而InP(111)表面由于是经过磷气氛退火处理的,在低暴露量下In—H与P—H键均可形成。InP(Ⅲ)面上只看到P—H损失峰,说明这个表面是完全以P原子结尾的。在(Ⅲ)面上出现小面的情形,则表面Ⅲ族和Ⅴ族原子均可同氢成键。 关键词：

HYDROGEN ADSORPTION ON GaAs AND InP (111), (111) SURFACES STUDIED BY HREELS

The hydrogen adsorption on GaAs and InP surfaces was studied by high resolution electron energy loss spectroscopy (HREELS). The stretching vibration modes of Ga-H, As-H, In-H and P-H bonds corresponding to different energy loss peaks in the spectra were all observed. However, the As-H vibration mode was usually confused with Ga-H "phonon echo" peak which is the Ga-H vibration mode plus an optical surface phonon loss. The identifying of As-H from the "phonon echo" peak could be done only by comparing the relative intensities of the loss peaks. The experimental HREELS show that the bonding between the adsorbed hydrogen and the surface atoms was determined largely by the surface atomic structure and electron distribution. For the GaAs (111) surface, only surface Ga atoms form bonds with the hydrogen under low exposure, while at high exposure both As-H and Ga-H bonds could be formed. On InP(lll) surface which was treated by annealing under phosphorus pressure, in addition to the In-H bond the P-H bond was formed even at low exposure. Only P-H loss peak could be seen on InP(lll), which suggested that such surface was fully terminated with P atoms. In the case of forming facets on (111) surface, both surface group Ⅲ and group V atoms could from bonds with hydrogen.