Enhanced NMR with Optical Pumping Yields 75 As Signals Selectively from a Buried GaAs Interface
Enhanced NMR with Optical Pumping Yields 75 As Signals Selectively from a Buried GaAs Interface
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采用光泵浦的增强型 NMR 可选择性地从掩埋 GaAs 界面产生 75 As 信号
DOI：
10.1021/jacs.6b08970
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发表时间：
2017
影响因子：
15
通讯作者：
Hayes, Sophia E.
中科院分区：
文献类型：
--
作者：
Willmering, Matthew M.;Ma, Zayd L.;Jenkins, Melanie A.;Conley, John F.;Hayes, Sophia E.
我们用光泵核磁共振（OPNMR）测量了用原子层沉积（ALD）法沉积的氧化铝膜钝化的单晶半绝缘GaAs的界面区的~（75）As信号。使用波长选择性光泵浦，激光器限制了收集OPNMR信号的体积。在这里，OPNMR信号从界面区域获得，并与本体产生的信号区分开。界面区域因破坏GaAs晶格立方对称性的相互作用而突出，导致核同位素的四极卫星，而“体”晶格的核磁共振名义上是不可分裂的。四极分裂的界面处产生的应变的基础上的GaAs和ALD沉积的氧化铝之间的晶格失配，由于它们的不同的热膨胀系数。这种应变的光谱证据可用于测量异质结边界和界面处的晶格畸变。
We have measured the75As signals arising from the interface region of single-crystal semi-insulating GaAs that has been coated and passivated with an aluminum oxide film deposited by atomic layer deposition (ALD) with optically pumped NMR (OPNMR). Using wavelength-selective optical pumping, the laser restricts the volume from which OPNMR signals are collected. Here, OPNMR signals were obtained from the interface region and distinguished from signals arising from the bulk. The interface region is highlighted by interactions that disrupt the cubic symmetry of the GaAs lattice, resulting in quadrupolar satellites for nuclearisotopes, whereas NMR of the “bulk” lattice is nominally unsplit. Quadrupolar splitting at the interface arises from strain based on lattice mismatch between the GaAs and ALD-deposited aluminum oxide due to their different coefficients of thermal expansion. Such spectroscopic evidence of strain can be useful for measuring lattice distortions at heterojunction boundaries and interfaces.