Vol.:(0123456789) 1 3 Applied Physics A (2018) 124:277 https://doi.org/10.1007/s00339-018-1688-0 CdTe quantum-dot-modifed ZnO nanowire heterostructure Kanchana Shahi 1  · R. S. Singh 2  · Ajaya Kumar Singh 3  · Mariya Aleksandrova 4  · Rabah Khenata 5 Received: 19 November 2017 / Accepted: 16 February 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract The efect of CdTe quantum-dot (QD) decoration on the photoluminescence (PL) behaviour of ZnO nanowire (NW) array is presented in the present work. Highly crystalline and vertically 40–50 nm diameter range and 1 µm in length aligned ZnO NWs are synthesized using low-cost method. The crystallinity and morphology of the NWs are studied by scanning electron microscopy and X-ray powder difraction methods.Optical properties of the nanowires are studied using photo-response and PL spectroscopy. CdTe QDs are successfully synthesized on ZnO nanowire surface by dip-coating method. ZnO NWs are sensitized with CdTe QDs characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and PL spectroscopy. The highly quenched PL intensity indicates the charge transfer at interface between CdTe QDs and ZnO NWs and is due to the formation of type-II heterostructure between QDs and NWs. Photo-response behaviour of heterostructure of the flm is also been incorporated in the present work. 1 Introduction Zinc-oxide (ZnO) nanostructure is a very promising material for optoelectronic application in the near-ultraviolet (UV) or blue spectral region because of its wurtzite crystal struc- ture, direct wide bandgap (3.37 eV), and high exciton bind- ing energy (60 meV) [1–4]. One-dimensional ZnO nano- structures such as nanorods [5], nanobelts [6], nanotubes [7], nanoribbons [8], nanowires [9, 10], and nanocables [11] have been fabricated by various methods. Among 1D nanostructures, ZnO nanowires and nanorods are frequently studied due to its easy fabrication and application in diferent nanodevices. Many diferent methods such as vapour–liq- uid–solid (VLS) [12], spray pyrolysis [13], metal organic chemical vapour deposition [14], and hydrothermal method [15] have been used to fabricate the 1D ZnO nanowires and nanorods. Hydrothermal method appears to have huge potential for nanodevice synthesis due to its low-cost, low temperature, and simple fabrication process. The unique chemical and physical properties and large surface-to-volume ratio make the ZnO NWs very useful in nanoelectronic devices. Using diferent sensitizers, the properties of ZnO NWs can be modifed according to the device requirement as well. The most widely used inorganic semiconductor sensitizers are CdS, Ag 2 S, CdSe, CdTe, and CdHgTe [16]. Among these sensitizers, CdTe has a high optical absorption coefcient (> 10 4  cm −1 ) and narrow band- gap of ~ 1.5 eV [17, 18]. It also forms a typical type-II band alignment with ZnO [19] allowing high-efcient electrons transfer from CdTe into ZnO [20]. Several promising methods have been used by diferent groups for heterostructure fabrication between ZnO and CdTe QDs. Aga et al. reported the signifcance of enhance- ments of photocurrent from the ZnO nanowires covered by CdTe quantum dots via a pulsed electron-beam technique [21]. Wang et al. successfully formed a heterostructure between ZnO nanowires/CdTe using electrochemical depo- sition method and studied the PC and PL behaviours [22]. Li et al. fabricated the ZnO NWs/CdTe heterostructure using chemical vapour deposition (CVD) method and dielectro- phoresis technique [23]. These approaches require sophisti- cated and expensive facilities. Hence, it would be interest- ing to fabricate the ZnO NWs/CdTe QD heterostructure at * Ajaya Kumar Singh ajayaksingh_au@yahoo.co.in 1 Department of Physics, Govt. V Y T P G Autonomous College, Durg, India 2 Department of Physics, Govt. L.C.S. Mahavidyalaya Chowki, Rajnandgaon, India 3 Department of Chemistry, Govt. V Y T P G Autonomous College, Durg, India 4 Department of Microelectronics, Technical University of Sofa, Sofa, Bulgaria 5 Faculty of Sciences and Technology, Mascara University, Mascara, Algeria