The dependence of aluminum lattice orientation on semiconductor lattice parameter in planar InAs/Al hybrid heterostructures

Journal Article · Thu Feb 20 00:00:00 EST 2020 · Journal of Crystal Growth

DOI:https://doi.org/10.1016/j.jcrysgro.2020.125570· OSTI ID:1608292

Wang, Tiantian ^[1]; Thomas, Candice ^[1]; Diaz, Rosa E. ^[2]; Gronin, Sergei ^[3]; Passarello, Donata ^[4]; Gardner, Geoffrey C. ^[3]; Capano, Michael A. ^[5]; Manfra, Michael J. ^[6]

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1. Purdue Univ., West Lafayette, IN (United States). Dept. of Physics and Astronomy, and Birck Nanotechnology Center
2. Purdue Univ., West Lafayette, IN (United States). Birck Nanotechnology Center
3. Purdue Univ., West Lafayette, IN (United States). Birck Nanotechnology Center, Microsoft Quantum Purdue
4. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
5. Purdue Univ., West Lafayette, IN (United States). Birck Nanotechnology Center, School of Electrical and Computer Engineering
6. Purdue Univ., West Lafayette, IN (United States). Dept. of Physics and Astronomy, Microsoft Quantum Purdue, School of Electrical and Computer Engineering, School of Materials Engineering, and Birck Nanotechnology Center

We present a detailed study of 7-nm thick Al layers epitaxially grown on In_xAl_1-xAs or Al_1-xGa_xSb_yAs_1-y (0 0 1) semiconductors using high-resolution transmission electron microscopy (HRTEM) and synchrotron X-ray diffraction (XRD). These techniques provide high spatial and high reciprocal space resolution information about Al lattice orientations and interfacial structure, highlighting the existence of a strong correlation between the surface lattice parameter of the semiconductor and the normal orientation of the aluminum film. The normal orientation of Al layers is found to be [1 1 1] when the in-plane semiconductor surface lattice parameter, a_S, is smaller than 5.98 Å, and is [1 1 0] when aS is larger than this value. In the transition between these lattice parameters where one orientation is preferred, both orientations may be observed. Concomitant with the change in normal orientation is an inversion in the strain state of the aluminum film. When the normal orientation is [1 1 1], the Al film is compressively strained; while for [1 1 0] normal orientations, the Al in-plane strain is tensile. An energy balance model, accounting for surface, interfacial, side-face, and strain energy, and the registry of lattice planes across the semiconductor/aluminum interface provide explanations for the observed normal orientation and strain inversion.

• Research Organization: SLAC National Accelerator Lab., Menlo Park, CA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 1608292
• Journal Information: Journal of Crystal Growth, Vol. 535, Issue C; ISSN 0022-0248
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
A1. Crystal structure
A1. Transmission electron microscopy
A1. X-ray diffraction
A3. Molecular beam epitaxy
B2. Semiconducting III–V materials