1. In this study, it has been found that annealing at ambient air at 500 ˚C of DC sputtered Mo bilayer produce MoO x nanobelts. Evolution of MoO x nanobelts growth has been studied by observing the structural, compositional and surface morphology properties at various annealing time. Annealing time greater than 90 minutes produces homogenous MoO x with MoO 3 as the dominating phase as revealed by XRD and Raman. Introduction Puvaneswaran Chelvanathan 1, Yulisa Yusoff 2, Samia A Nadi 1, Towhid H Chowdhury 1, Mohammad J Rashid 1, Md Akhtaruzzaman 1, Nowshad Amin 1, 2, 3* 1 Solar Energy Research Institute, The National University of Malaysia, 43600 Bangi, Selangor, Malaysia 2 Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, The National University of Malaysia, 43600 Bangi, Selangor, Malaysia 3 Advanced Materials Research Chair, Chemistry Department, College of Sciences, King Saud University, Riyadh 11451, Saudi Arabia * E-Mail: nowshad@eng.ukm.my Formation of MoO x Nanobelts from Simple and Cost Effective Air Annealing DC- Sputtered Bi-Layer Molybdenum Thin Film Molybdenum (Mo) is the preferred choice for back contact material in CIGS and CZTS thin film solar cells due to its desirable electrical properties and compatibility to the subsequent absorber layer deposition process. This paper elucidates the properties of MoO x nanobelts grown from air annealed DC-sputtered Mo bi-layers. Molybdenum thin films were fabricated by DC sputtering method with DC power and temperature fixed at 100 W and room temperature respectively. First layer was sputtered at higher pressure to promote adhesion meanwhile second layer was sputtered at lower pressure to increase the conductivity of the film. This recipe is widely used as optimum condition for Mo back contact deposition. Finally, sputtered Mo film annealed at 500 ˚C in air for different time ranging from 30 minutes to 150 minutes. The grown Mo/MoO x structures then were characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometer (XRD), Atomic Force Microscopy (AFM) and Hall measurement equipment to elucidate the structural and electrical properties.  All Mo films deposited passed the “Adhesive Tape” test indicating good adhesion with soda lime glass substrate.  MoO x compounds which formed are primarily MoO 3 and Mo 4 O 11 as seen from the XRD spectra  MoO 3 is the dominant phase with preferential orientation of (021).  Raman spectra indicates water molecules are intercalated with MoO 3 in the initial stage of growth and subsequent water desorption occurs for annealing time more than 60 minutes.  FESEM images indicates growth of MoO x nanobelts with intermediate seed layer forming underneath (see image (d))  Surface topology probed by AFM indicates homogenous surface and larger grain clusters are produced as annealing period is increased. Major Findings and Discussions Conclusion Experimental & Characterization Procedures ENGE 2014, 16 th to 19 th Nov 2014, Jeju, Korea Surface morphology and Cross Sectional View of Air Annealed Mo Films (a) and (b) 30 Minutes, (c) and (d) 150 minutes Surface morphology and Cross Sectional View of Air Annealed Mo Films (a) and (b) 30 Minutes, (c) and (d) 150 minutes XRD patterns with various annealing time Substrate Cleaning Process Methanol, acetone, methanol, DI water sonification for 15 minutes in each solvent Substrate Cleaning Process Methanol, acetone, methanol, DI water sonification for 15 minutes in each solvent DC-Sputtered Mo Film Base pressure = 10 -6 Torr Argon Flow = 2 -3 SCCM DC Power = 100 W Sub. Rotation = 10 RPM Sub. Temperature = RT Deposition Time = 120 min. Mo Thickness = 1 µm DC-Sputtered Mo Film Base pressure = 10 -6 Torr Argon Flow = 2 -3 SCCM DC Power = 100 W Sub. Rotation = 10 RPM Sub. Temperature = RT Deposition Time = 120 min. Mo Thickness = 1 µm Characterization Methods XRD FESEM Hall Measurement AFM Raman Characterization Methods XRD FESEM Hall Measurement AFM Raman Air- Annealed Mo Film Hot Plate Annealing Annealing Time = 30-150 min. Annealing Temperature : 500˚C Natural cooling to RT Air- Annealed Mo Film Hot Plate Annealing Annealing Time = 30-150 min. Annealing Temperature : 500˚C Natural cooling to RT Raman Spectra for Air-Annealed Mo Thin Films Surface Topography Atomic Microscope Force Image of 150 mins Air Annealed Film. (a) 2D (b) 3D (a)(b) (a)(b) (d)(c)