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Fabrication of pulsed laser-deposited Cr-doped zinc oxide thin films: structural, morphological, and optical studies A. H. Shah1,*

, Rayees Ahmad Zargar1, Manju Arora2, and P. B. Sundar3

1

Department of Physics, Baba Ghulam Shah Badshah University, Rajouri, J&K 185234, India National Physical Laboratory, CSIR, New Delhi 110012, India 3 Department of Physics, Bharathiar University, Coimbatore, Tamilnadu 641046, India 2

Received: 1 May 2020

ABSTRACT

Accepted: 8 October 2020

High-quality c-axis-oriented Cr-doped ZnO thin films were grown on 100-lmthick Si (100) wafer substrate by Pulsed Laser Deposition (PLD) technique. The PLD is a versatile technique for growing thin films and a wide range of materials. The structural analyses confirm the wurtzite structure of synthesized samples and are preferentially oriented along c-axis perpendicular to substrate the surface. The intensity of defect-induced mode frequency for Cr-doped ZnO film increased due to the formation of highly crystalline films. In Raman spectra, E2 (high) mode shows redshift owing to optical phonon confinement induced by uncertainty in photon wave vectors i.e., downshift of Raman peaks. Cr-doped ZnO thin film consists of nanorod-shaped grains of different sizes. Each rod possesses width in a range of 85–93 nm and length upto several hundred nanometres. The decrease in peak intensity of Cr-doped ZnO film photoluminescence (PL) spectrum is attributed to a fall in the electron–hole recombination process. In visible region of PL spectra, green light emission peak at about 567 nm was associated with defects in ZnO. It is observed after doping root mean square (RMS) roughness increases with which means the surfaces becomes rough and grain size increases.

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Springer Science+Business

Media, LLC, part of Springer Nature 2020

1 Introduction Zinc oxide (ZnO) is generally explored as versatile semiconductor oxide material both in bulk and nanoform. It is because of its resistivity control over in range from 10-3 to 105 X cm, towering transparency in the visible region, physical stability at

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https://doi.org/10.1007/s10854-020-04632-9

ambient temperature, direct wide band gap energy (* 3.37 eV), and huge exciton binding energy (60 meV) [1–3]. Lattice constants of hexagonal wurt˚ and c = 5.12 A ˚ zite-structured ZnO are a = 3.25 A where each Zn atom is tetrahedrally synchronized to four O atoms. They have layers occupied by zinc atoms alternatively with layers occupied by oxygen

J Mater Sci: Mater Electron

atoms [4]. Different kinds of intrinsic defects such as substitutional and interstitial Zn vacancies, paramagnetic O vacancies, interstitial O, and antisite O (OZn) are present in pure ZnO. These intrinsic defects are generally produced at acceptor or donor level within the band gap which influences different physical properties of ZnO. Another important way to modify these properties is to dope ZnO by different metal ions depending upon their device applications. Recently, work is going in their u