New Insights into the Role of Weak Electron⁻Phonon Coupling in Nanostructured ZnO Thin Films.
High-quality crystalline nanostructured ZnO thin films were grown on sapphire substrates by reactive sputtering. As-grown and post-annealed films (in air) with various grain sizes (2 to 29 nm) were investigated by scanning electron microscopy, X-ray diffraction, and Raman scattering. The electron⁻phonon coupling (EPC) strength, deduced from the ratio of the second- to the first-order Raman scattering intensity, diminished by reducing the ZnO grain size, which mainly relates to the Fröhlich interactions. Our finding suggests that in the spatially quantum-confined system the low polar nature leads to weak EPC. The outcome of this study is important for the development of nanoscale high-performance optoelectronic devices.
['Gandhi|Ashish C|AC|0000-0002-1900-8702', 'Yeoh|Wei-Shan|WS|', 'Wu|Ming-An|MA|', 'Liao|Ching-Hao|CH|', 'Chiu|Dai-Yao|DY|', 'Yeh|Wei-Li|WL|', 'Huang|Yue-Lin|YL|']
Raman scattering electron–phonon coupling polar semiconductors quantum confinement zinc oxide