Contents lists available at ScienceDirect Materials Science in Semiconductor Processing journal homepage: www.elsevier.com/locate/mssp Effect of quantum confinement in CdSe/Se multilayer thin films prepared by PVD technique S. Anandh Jesuraj a , Suganthi Devadason b, ⁎ , M. Melvin David Kumar c a Department of Physics, Karunya University, Tamilnadu, India b Department of Physics, Hindustan Institute of Technology and Science, Tamilnadu, India c Department of Physics, Adhithanar College of Arts and Science, Tamilnadu, India ARTICLE INFO Keywords: Quantum confinement PVD technique CdSe/Se Multilayer thin films Optical properties ABSTRACT Quantum confined nanostructures were prepared by depositing alternate CdSe and Se thin layers. The structural and optical characterizations of the prepared samples were carried out using X-ray diffractometer (XRD), Field emission scanning electron microscope (FE-SEM), UV–visible and photoluminescence spectrophotometers. XRD studies revealed that CdSe nanocrystals are polycrystalline in nature with hexagonal phase. The crystallite size of CdSe nanoparticles was found to be in the range of 8–14 nm. FE-SEM images also confirmed that the embedded nanocrystalline CdSe particles are a few nanometers in dimension having a spherical morphology. The quantum confinement of charge carriers in the multilayer (ML) films is evident from the shifting of absorption edge to lower wavelengths in the UV–visible spectra. An increase in the energy band gap with decreasing thickness of the CdSe sub-layer has been ascribed to quantum confinement effect and the subsequent crystallite size calculated from Brus approximation method is ~3.5 nm. Hence, the results indicate that the quantum confinement effect could be realized in CdSe nanocrystallites by ML stacking structure of CdSe and Se in appropriate thickness ratio. 1. Introduction For a couple of decades, many researchers are focusing on low dimensional nanostructured materials because of their tunable proper- ties. Generally, the II-VI group compounds such as CdSe, CdTe, CdS, etc., exhibit distinctive properties when they are in low dimensional structure. Confining charge carriers in these materials is relatively uncomplicated due to their large Bohr exciton diameter. In the present work, CdSe material has been chosen for their remarkable properties leading to potential applications in optoelectronics [1], solar cells [2], high efficiency thin film transistors [3], light emitting diodes [4] and sensors [5]. Also, CdSe has a larger Bohr exciton diameter of 11.2 nm which enables to act as a suitable material to achieve quantum confined nanostructures. Single selenium layer consists of random chains that allows both electrons and holes to attain measurable drift mobilities [6]. When thin layers of CdSe and Se are stacked one over another, the movement of electrons are restricted due to lattice mismatch that exist between the layers. The deposition of CdSe and Se layers one over another in alternate manner produces the quantum well structures. However, preparation of such structure requires convenient fabrication technique which provides precise control over the thicknesses of sublayers and ambient coating conditions. Physical vapour deposition (PVD) [7], pulsed laser deposition (PLD) [8], molecular beam epitaxy (MBE) [9] and sputtering [10] methods have been adopted by few research groups so as to fabricate the nanostructures of CdSe material. In our work, we have employed thermal evaporation technique to prepare the quantum confined structures in CdSe/Se multilayer sam- ples. Bing Gao et al. (2014) reported that as the size of CdSe quantum dots (QD) varied from 1.84 to 4.50 nm, the absorption peak red shifted from 450 to 560 nm which matched with the absorption range of the solar spectrum. In the present study, a simple method has been described to fabricate the CdSe nanocrystallites (NC) for the applications of optoe- lectronic devices. The CdSe NCs are confined by the influence of rings and chains present in Se sublayer. Then, the science behind the possible quantized electronic transitions between the energy levels of CdSe NCs and constituent materials through direct and indirect modes are explained. The role of Se in quantum dot formation, band-edge absorption, spin-orbit splitting of valence band and shift in band gap energies due to different electronic transitions are explained with analytical interpretations. http://dx.doi.org/10.1016/j.mssp.2017.03.019 Received 28 October 2016; Received in revised form 15 March 2017; Accepted 21 March 2017 ⁎ Corresponding author. E-mail address: dsuganthi2002@gmail.com (S. Devadason). Materials Science in Semiconductor Processing 64 (2017) 109–114 1369-8001/ © 2017 Elsevier Ltd. All rights reserved. MARK