National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
Nanoscale Res Lett. 2013 Apr 12;8(1):169. doi: 10.1186/1556-276X-8-169.
High-resolution synchrotron radiation photoemission was employed to study the effects of atomic-layer-deposited trimethylaluminum (TMA) and water on Ga-rich GaAs(001)-4 × 6 and As-rich GaAs(001)-2 × 4 surfaces. No high charge states were found in either As 3d or Ga 3d core-level spectra before and after the deposition of the precursors. TMA adsorption does not disrupt the GaAs surface structure. For the (4 × 6) surface, the TMA precursor existed in both chemisorbed and physisorbed forms. In the former, TMA has lost a methyl group and is bonded to the As of the As-Ga dimer. Upon water purge, the dimethylaluminum-As group was etched off, allowing the now exposed Ga to bond with oxygen. Water also changed the physisorbed TMA into the As-O-Al(CH3)2 configuration. This configuration was also found in 1 cycle of TMA and water exposure of the (2 × 4) surface, but with a greater strength, accounting for the high interface defect density in the mid-gap region.
采用高分辨率同步辐射光电子能谱研究了原子层沉积的三甲基铝（TMA）和水对富 Ga 的 GaAs(001)-4×6 和富 As 的 GaAs(001)-2×4 表面的影响。在沉积前体前后，在 As 3d 或 Ga 3d 芯能级谱中均未发现高电荷态。TMA 吸附不会破坏 GaAs 表面结构。对于 (4×6) 表面，TMA 前体以化学吸附和物理吸附两种形式存在。在前一种情况下，TMA 失去了一个甲基基团，并与 As-Ga 二聚体的 As 键合。在水冲洗时，二甲基铝-As 基团被蚀刻掉，现在暴露的 Ga 与氧键合。水还将物理吸附的 TMA 转化为 As-O-Al(CH3)2 结构。在 (2×4) 表面的 TMA 和水暴露 1 个循环中也发现了这种结构，但强度更大，这解释了在隙区中部存在高界面缺陷密度的原因。
