Effects of Substrate Temperature on Optical, Structural, and Surface Properties of Metal-Organic Vapor Phase Epitaxy-Grown MgZnO Films

Jiamin Liu; Deng Xie; Zhe Chuan Feng; Manika Tun Nafisa; Lingyu Wan; Zhi-Ren Qiu; Dong-Sing Wuu; Chuanwei Zhang; Jeffrey Yiin; Hao-Hsiung Lin; Weijie Lu; Benjamin Klein; Ian T Ferguson; Shiyuan Liu

doi:10.3390/nano14231957

Effects of Substrate Temperature on Optical, Structural, and Surface Properties of Metal-Organic Vapor Phase Epitaxy-Grown MgZnO Films

Nanomaterials (Basel). 2024 Dec 5;14(23):1957. doi: 10.3390/nano14231957.

Authors

Jiamin Liu¹, Deng Xie², Zhe Chuan Feng^{1

3

4}, Manika Tun Nafisa³, Lingyu Wan⁵, Zhi-Ren Qiu⁶, Dong-Sing Wuu⁷, Chuanwei Zhang¹, Jeffrey Yiin³, Hao-Hsiung Lin⁸, Weijie Lu⁹, Benjamin Klein³, Ian T Ferguson³, Shiyuan Liu^{1

10}

Affiliations

¹ State Key Laboratory of Intelligent Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
² School of Electronic & Electrical Engineering and Physics, Fujian University of Technology, Fuzhou 350000, China.
³ Southern Polytechnic College of Engineering and Engineering Technology, Kennesaw University, Marietta, GA 30060, USA.
⁴ Science Exploring Laboratory, Arbour Glenn Drive, Lawrenceville, GA 30043, USA.
⁵ Center on Nano-Energy Research, Guangxi Key Laboratory for the Relativistic Astrophysics, Institute of Science and Technology for Carbon Peak & Neutrality, School of Physical Science & Technology, Guangxi University, Nanning 530004, China.
⁶ State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, China.
⁷ Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, Puli, Nantou 54561, Taiwan.
⁸ Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
⁹ Hexagonal Scientific Laboratory, LLC, Dayton, OH 45459, USA.
¹⁰ Optics Valley Laboratory, Wuhan 430074, China.

Abstract

MgZnO possesses a tunable bandgap and can be prepared at relatively low temperatures, making it suitable for developing optoelectronic devices. Mg_xZn_1-xO (x~0.1) films were grown on sapphire by metal-organic vapor phase epitaxy under different substrate-growth temperatures T_s of 350-650 °C and studied by multiple characterization technologies like X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Raman scattering, extended X-ray absorption fine structure (EXAFS), and first-principle calculations. The effects of T_s on the optical, structural, and surface properties of the Mg_0.1Zn_0.9O films were studied penetratively. An XRD peak of nearly 35° was produced from Mg_0.1Zn_0.9O (0002) diffraction, while a weak peak of ~36.5° indicated MgO phase separation. SE measurements and analysis determined the energy bandgaps in the 3.29-3.91 eV range, obeying a monotonically decreasing law with increasing T_s. The theoretical bandgap of 3.347 eV, consistent with the SE-reported value, demonstrated the reliability of the SE measurement. Temperature-dependent UV-excitation Raman scattering revealed 1LO phonon splitting and temperature dependency. Zn-O and Zn-Zn atomic bonding lengths were deduced from EXAFS. It was revealed that the surface Mg amount increased with the increase in T_s. These comprehensive studies provide valuable references for Mg_0.1Zn_0.9O and other advanced materials.

Keywords: Mg0.1Zn0.9O; Raman spectroscopy; X–ray diffraction; X–ray photoelectron spectroscopy; enharmonic phonon process; metal–organic vapor phase epitaxy; near-edge X–ray absorption fine structure; spectroscopic ellipsometry; synchrotron radiation.

Abstract

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