Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602.
ACS Appl Mater Interfaces. 2013 Feb;5(3):949-57. doi: 10.1021/am302537b. Epub 2013 Jan 31.
High quality surface passivation on bulk-GaAs substrates and epitaxial-GaAs/Ge (epi-GaAs) layers were achieved by using atomic layer deposited (ALD) titanium aluminum oxide (TiAlO) alloy dielectric. The TiAlO alloy dielectric suppresses the formation of defective native oxide on GaAs layers. X-ray photoelectron spectroscopy (XPS) analysis shows interfacial arsenic oxide (As(x)O(y)) and elemental arsenic (As) were completely removed from the GaAs surface. Energy dispersive X-ray diffraction (EDX) analysis and secondary ion mass spectroscopy (SIMS) analysis showed that TiAlO dielectric is an effective barrier layer for reducing the out-diffusion of elemental atoms, enhancing the electrical properties of bulk-GaAs based metal-oxide-semiconductor (MOS) devices. Moreover, ALD TiAlO alloy dielectric on epi-GaAs with AlGaAs buffer layer realized smooth interface between epi-GaAs layers and TiAlO dielectric, yielding a high quality surface passivation on epi-GaAs layers, much sought-after for high-speed transistor applications on a silicon platform. Presence of a thin AlGaAs buffer layer between epi-GaAs and Ge substrates improved interface quality and gate dielectric quality through the reduction of interfacial layer formation (Ga(x)O(y)) and suppression of elemental out-diffusion (Ga and As). The AlGaAs buffer layer and TiAlO dielectric play a key role to suppress the roughening, interfacial layer formation, and impurity diffusion into the dielectric, which in turn largely enhances the electrical property of the epi-GaAs MOS devices.
在体 GaAs 衬底和外延 GaAs/Ge（外延 GaAs）层上，通过使用原子层沉积（ALD）钛铝氧化物（TiAlO）合金电介质实现了高质量的表面钝化。TiAlO 合金电介质抑制了 GaAs 层上有缺陷本征氧化物的形成。X 射线光电子能谱（XPS）分析表明，GaAs 表面的界面砷氧化物（As(x)O(y)）和元素砷（As）完全被去除。能量色散 X 射线衍射（EDX）分析和二次离子质谱（SIMS）分析表明，TiAlO 电介质是减少元素原子扩散的有效阻挡层，增强了基于体 GaAs 的金属氧化物半导体（MOS）器件的电学性能。此外，在具有 AlGaAs 缓冲层的外延 GaAs 上的 ALD TiAlO 合金电介质实现了外延 GaAs 层和 TiAlO 电介质之间的平滑界面，在外延 GaAs 层上实现了高质量的表面钝化，这是在硅平台上实现高速晶体管应用所急需的。在外延 GaAs 和 Ge 衬底之间存在薄的 AlGaAs 缓冲层，通过减少界面层形成（Ga(x)O(y)）和抑制元素扩散（Ga 和 As），改善了界面质量和栅介质质量。AlGaAs 缓冲层和 TiAlO 电介质在抑制粗糙化、界面层形成和杂质扩散到电介质中起着关键作用，这反过来又大大增强了外延 GaAs MOS 器件的电学性能。
