Transactions of The Indian Institute of Metals Vol. 64, Issue 1, February 2011, pp. ISRS D-10-150 Synthesis and characterization of one dimensional semiconducting nanorods and nanobelts G. Ramalingam 1 , J. Madhavan 1 , P. Sagayaraj 1 , S. Selvakumar 2 , R. Gunaseelan 1 and R. Jerald Vijay 1 1 Department of Physics, Loyola College, Chennai- 600 034, India 2 Department of Physics, L.N.Govt.College, Ponneri -601 204, India E-mail: jmadhavang@yahoo.com. Received 01 November 2010 Revised 15 February 2011 Accepted 01 March 2011 Online at www.springerlink.com © 2011 TIIM, India Abstract CdSe nanorods, nanobelts are synthesized via a simple sacrificial template assisted solvothermal route at a moderate temperature of 180 º C. The influences of introducing sacrificial template, hydrazine hydrate (N 2 H 4 .H 2 O) as the reducing agent, ammonia (NH 3 .H 2 O) and NaOH as the complexing agent on the morphology and size of the obtained CdSe nanorods and nanobelts are investigated and reported. CdSe nanorods with a mean diameter and length of 25 nm and 82 nm respectively are synthesized and the problem of handling the stacking faults present in the long CdSe is analyzed. The structural phase, morphology and the optical properties of CdSe nanorods and nanobelts are studied using powder X-ray diffraction, TEM/HRTEM, UV-visible absorption spectroscopy and photoluminescence (PL) spectroscopy respectively. 1. Introduction One dimensional (1D) semiconducting nanostructures, such as nanorods, nanowires, nanobelts and nanotubes have recently attracted substantial research interest because of their unusual optical and electronic properties and potential applications in nanodevices (Peng. X, 2003, Li. L-S. et al, 2002, Rao. C.N.R. 2003). CdSe is one of the members of the II/VI semiconductor family having a suitable band gap to match the maximum solar spectrum and also high photosensitivity, it has been proposed as a working element for nanotransistor (Klein. D.L. et al, 1997), electrochromic material(Wang. C et al, 2001) and charge coupling devices(Woo W.K.et al, 2002). CdSe nanowires and nanotubes(Rao, C.N.R 2003) have also been fabricated using electrochemical and chemical methods that find usages in fabricating optoelectronic devices like solar cell, where the power conversion efficiency of nanorods has been demonstrated to be higher than that of quantum dots (QDs) (Peng Q et al 2001, Peng X. 2003, Jing X.C. et al 2003, Milliron. D.J. et al 2005). Core-shell nanostructured CdSe/ ZnS quantum dot exhibits lasing effects and can be used for fluro-immunoassays, biological imaging and biosensors (Zhanyu Wu et al 2009). The preparation of well controlled 1D nanorods (NRs) arrangement is still a “state-of-the-art” problem based on arrangement and also chemical attachments of the NRs (Tolbert S.H.and Alivisatos A.P.1994 ). CdSe nanorods have polarized photoluminescence up to 100 % (Chen X., 2001). The advent of new methods to precisely control the diameter and the length of rod-like CdSe nanocrystals provides a new set of experimental data against which the theory can be tested (Peng. X. 2000, Peng.Q et al 2002). Lian Ouyang et al (2007 )synthesized CdSe hetrostructure nanorod using solution liquid solid (SLS) Keywords: semiconductors; nanorods; nanobelts; CdSe nanoparticles; hydrazine hydrate; NaOH method and obtained nanorods of 30 nm diameter (Ouyang et al (2007)). In the “oriented attachments” method, by using tri-n-butylphosphine (TBP) as a reducing agent, Manna et al obtained CdSe NRs of length 34 nm (Manna. L 2000). Lifei Xi et al (2008) synthesized CdSe NRs by a novel reverse micelles assisted hydrothermal method, and used sodium bis (2-ethylhexyl) sulfosuccinate (AOT) as an anionic surfactant and hydrazine hydrate(N 2 H 4 .H 2 O) as a reducing agent in a water-in-oil microemulsion. Further, they have made an interesting observation that AOT controls the length, while hydrazine hydrate controls the diameter of the growing nanocrystals. So far, the reported CdSe nanobelts were synthesized by chemical vapur deposition (CVD) and thermal evaporation techniques which are cost expensive. In the study of growth mechanisms, CdSe nanosaws synthesized by Ma et al (2004), were proposed to be induced by a surface polarization to form the particular morphology. Recently Venugopal et al (2005) fabricated single-crystalline CdSe nanowires, nanobelts and sheets by CVD assisted laser ablation techniques. CdSe nanobelts that range in length from several tens to hundred micrometers and in thickness from 40-70 nm were achieved at 550 °C experimental conditions. Pana et al (2007) fabricated single-crystal CdSe nanobelts through Au-Catalyzed physical evaporation route. In his work high purity helium (He) was introduced into the quartz tube with a flow rate, 5 sccm and the furnace was rapidly heated to high temperature. Many researchers have reported that under proper conditions nanoparticles can be self-assembled into 1-D nanostructures through magnetic-dipole moments (Nishinaka et al 2005), electric dipole moments (Pileni. M.P.2001, Tang.A. et al 2002) or oriented attachment (Peng. X. 2001) technique. However, self-assembly requires more rigorous conditions. The sacrificial template route can partially overcome these 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67