Department of Physics and Astronomy , University of Turku , FI-20014 Turku , Finland.
Renewable Energies , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , DE-14109 Berlin , Germany.
ACS Appl Mater Interfaces. 2018 Dec 26;10(51):44932-44940. doi: 10.1021/acsami.8b17843. Epub 2018 Dec 14.
InAs crystals are emerging materials for various devices like radio frequency transistors and infrared sensors. Control of oxidation-induced changes is essential for decreasing amounts of the harmful InAs surface (or interface) defects because it is hard to avoid the energetically favored oxidation of InAs surface parts in device processing. We have characterized atomic-layer-deposition (ALD) grown AlO/InAs interfaces, preoxidized differently, with synchrotron hard X-ray photoelectron spectroscopy (HAXPES), low-energy electron diffraction, scanning tunneling microscopy, and time-of-flight elastic recoil detection analysis. The chemical environment and core-level shifts are clarified for well-embedded InAs interfaces (12 nm AlO) to avoid, in particular, effects of a significant potential change at the vacuum-solid interface. High-resolution As 3d spectra reveal that the AlO/InAs interface, which was sputter-cleaned before ALD, includes +1.0 eV shift, whereas As 3d of the preoxidized (3 × 1)-O interface exhibits a shift of -0.51 eV. The measurements also indicate that an AsO type structure is not crucial in controlling defect densities. Regarding In 4d measurements, the sputtered InAs interface includes only a +0.29 eV shift, while the In 4d shift around -0.3 eV is found to be inherent for the crystalline oxidized interfaces. Thus, the negative shifts, which have been usually associated with dangling bonds, are not necessarily an indication of such point defects as previously expected. In contrast, the negative shifts can arise from bonding with O atoms. Therefore, specific care should be directed in determining the bulk-component positions in photoelectron studies. Finally, we present an approach to transfer the InAs oxidation results to a device process of high electron mobility transistors (HEMT) using an As-rich III-V surface and In deposition. The approach is found to decrease a gate leakage current of HEMT without losing the gate controllability.
砷化铟晶体是各种器件（如射频晶体管和红外传感器）的新兴材料。控制氧化引起的变化对于减少有害的砷化铟表面（或界面）缺陷至关重要，因为在器件处理过程中，很难避免砷化铟表面部分的能量有利氧化。我们使用同步加速器硬 X 光光电电子能谱（HAXPES）、低能电子衍射、扫描隧道显微镜和飞行时间弹性反冲探测分析，对不同预氧化的原子层沉积（ALD）生长的 AlO/InAs 界面进行了表征。化学环境和芯能级位移得到了澄清，对于嵌入良好的 InAs 界面（12nm AlO），特别是避免了真空-固体界面的显著电势变化的影响。高分辨率 As 3d 光谱表明，在 ALD 之前经过溅射清洁的 AlO/InAs 界面包括+1.0eV 的位移，而预氧化（3×1）-O 界面的 As 3d 则表现出-0.51eV 的位移。测量还表明，AsO 型结构对于控制缺陷密度并不是至关重要的。关于 In 4d 测量，溅射的 InAs 界面仅包括+0.29eV 的位移，而在结晶氧化界面中发现的约-0.3eV 的 In 4d 位移是固有的。因此，负位移，通常与悬键相关联，不一定是以前预期的那种点缺陷的指示。相反，负位移可能是由于与 O 原子的键合引起的。因此，在光电子研究中确定体相成分的位置时应特别注意。最后，我们提出了一种使用富砷 III-V 表面和 In 沉积将砷化铟氧化结果转移到高电子迁移率晶体管（HEMT）器件工艺中的方法。该方法被发现可以降低 HEMT 的栅漏电流，而不会失去栅极的可控性。
