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采用激光分子束外延方法(L-MBE),在GaAs(001)衬底上同质外延GaAs薄膜。利用反射式高能电子衍射(RHEED)研究了材料沉积过程中的各级条纹及其强度的变化,进而得出GaAs薄膜外延生长的适宜激光能量和沉积温度分别为500 mJ和570℃。RHEED强度随时间的变化曲线表明,GaAs为良好的层状外延生长模式,并随着沉积时间延长,层状生长模式逐渐向岛状模式转变。实验研究还表明层状生长的GaAs薄膜经表面弛豫后,可以得到更好的平整表面,并出现GaAs(001)-(2×4)的表面重构。原位X射线光电子能谱仪(XPS)研究表明沿(001)面外延的GaAs薄膜表面Ga∶As化学计量比约为52∶48,出现Ga的聚集。
Homogeneous epitaxial GaAs films were deposited on GaAs (001) substrates by laser molecular beam epitaxy (L-MBE). The variation of the streaks and their intensities at various levels during the material deposition was studied by reflection high energy electron diffraction (RHEED), and the suitable laser energy and deposition temperature for GaAs epitaxial growth were 500 mJ and 570 ℃, respectively. The curve of RHEED intensity with time shows that GaAs is a good layered epitaxial growth mode, and with the deposition time extended, the layered growth mode gradually changes to the island mode. Experimental studies have also shown that the surface of GaAs thin film grown by surface relaxation, get a better surface roughness, and GaAs (001) - (2 × 4) surface reconstruction. In situ X-ray photoelectron spectroscopy (XPS) studies have shown that Ga: As stoichiometry is about 52:48 on the GaAs film epitaxially grown along the (001) plane, resulting in the aggregation of Ga.