Applied Surface Science 307 (2014) 280–286 Contents lists available at ScienceDirect Applied Surface Science journal h om epa ge: www.elsevier.com/locate/apsusc Structural and optical study of Li doped CuO thin ﬁlms on Si (1 0 0) substrate deposited by pulsed laser deposition Prakash Chand a , Anurag Gaur a,∗ , Ashavani Kumar a , Umesh Kumar Gaur b a Department of Physics, National Institute of Technology, Kurukshetra 136119, India b Centre of Nanotechnology, Indian Institute of Technology, Roorkee 247667, India a r t i c l e i n f o Article history: Received 23 January 2014 Received in revised form 4 March 2014 Accepted 3 April 2014 Available online 13 April 2014 Keywords: CuO thin ﬁlms Optical properties PL and Raman spectroscopy a b s t r a c t In the present study, we report structural and optical properties of Cu 1 - x Li x O thin ﬁlms grown on Si (1 0 0) substrates by pulsed laser deposition at different doping concentrations (x = 0.0, 0.05, 0.07 and 0.09). The XRD spectra indicates the formation of polycrystalline CuO thin ﬁlms and the crystallite size, calculated through XRD data is found to be increased from 7 to 14 nm for the samples with x = 0 to 0.09, respectively. FESEM analysis shows that the average size of Cu 1 - x Li x O nanostructures increases from 47 to 97 nm and AFM analysis also shows that the average size of Cu 1 - x Li x O nanostructures increases from 35 to 79 nm by increasing the Li doping concentrations from x = 0 to 0.09, respectively. Energy dispersive X-ray analysis with elemental mapping of the Li-doped CuO thin ﬁlms shows that the Li dopants are incorporated homogeneously into the CuO thin ﬁlm matrix. Moreover, Raman and photoluminescence spectra also conﬁrm the single-phase formation of CuO thin ﬁlms. A signiﬁcant reduction in optical energy band gap is observed from 2.99 to 2.76 eV with an increase of Li concentration from 0 to 9%, respectively. © 2014 Elsevier B.V. All rights reserved. 1. Introduction An advancement of nanoscience and technology has not been only stimulating the discovery of new phenomenon and innova- tive theory in science but it also plays an important role in industrial revolutions and becoming a new dynamic force for the economic development for the 21st century [1,2]. In recent years, nanoscale transition metal oxides thin ﬁlms have attracted the researcher’s interest because of both fundamental and technological point of view. Among all the transition metal oxides, cupric oxide (CuO) thin ﬁlms have attracted much interest due to their peculiar properties and potential applications in different ﬁelds of science and technol- ogy such as solar cell technology, ﬁeld emission, magnetic storage media, application in lithium ion batteries, gas sensing, drug deliv- ery, capacitors, diodes, transducers, magnetic resonance imaging, and ﬁeld emission devices and so forth [2–10] because of their novel electronic, mechanical, magnetic, and optical properties com- pared with those of conventional bulk materials. For technological applications the thorough understanding of size, morphology con- trolled appearance of unusual properties are signiﬁcant. Cupric oxide (CuO, tenorite) is a monoclinic p-type semiconductor with ∗ Corresponding author. Tel.: +91 1744 233549; fax: +91 1744 238050. E-mail address: anuragdph@gmail.com (A. Gaur). a narrow band gap of 1.21–2.1 eV at room temperature [11–13]. An important advantage of using CuO in device applications is that it is a low cost, non-toxic transition metal oxide, with high theo- retic capacity (670 mAh g -1 ), easily produced and its constituents are available in abundance [14]. Copper oxide thin ﬁlms have many advantages for catalysts and solar energy conversion applications because they have a high activity and selectivity in oxidation and reduction reactions [15]. A broad variety of techniques have been used for the deposition of nano crystalline CuO thin ﬁlms, such as molecular beam epitaxy, sol–gel, thermal evaporation, magnetron sputtering, chemical vapor deposition and pulsed laser deposition [16–20]. Among these methods, pulsed laser deposition (PLD) has been proved to be a very efﬁcient method in depositing metal oxide thin ﬁlms because PLD offers the advantages such as depo- sition at relatively high oxygen pressure, high deposition rate and growth of highly oriented crystalline ﬁlms at low substrate tem- perature. Cupric oxide is also a proﬁcient material for fabricating optical switches, high T C superconductors and material with giant magneto resistance [21]. Due to such properties, CuO has received much attention over the past few years because it has a wide range of properties that depend on shape and doping. Doping pro- cess has been widely used for alteration of the electronic structure of CuO nanostructures to achieve novel or improved properties. Many authors have reported the improvement in the material’s characteristic properties using various dopants [22]. The optical http://dx.doi.org/10.1016/j.apsusc.2014.04.027 0169-4332/© 2014 Elsevier B.V. All rights reserved.