Some studies on Molybdenum doped Indium oxide thin films rf sputtered at room temperature
- PDF / 411,740 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 56 Downloads / 238 Views
0928-GG12-03
Some studies on Molybdenum doped Indium oxide thin films rf sputtered at room temperature E. Elangovan1, P Barquinha1, A Pimental1, A. S. Viana2, R Martins1, and E Fortunato1 1 Materials Science Department, New University of Lisbon, CENIMAT/FCT/UNL, Campus de Caparica, Caparica, 2829-516, Portugal 2 Faculdade de Ciências da Universidade de Lisboa, Laboratório de SPM, Ed.ICAT, Campo Grande, Lisboa, 1749-016, Portugal ABSTRACT Thin films of molybdenum doped indium oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of oxygen volume percentage (OVP) ranging 1.4 - 10.0 % in the sputtering chamber. The thickness of the films found varying between 180 and 260 nm. The X-ray diffraction pattern showed the films are polycrystalline with the peaks corresponding to (222) and (400) planes and one among them showing as a preferential orientation. It is observed that the preferred orientation changes from (222) plane to (400) as the OVP increases from 1.4 to 10.0 %. The transmittance spectra were found to be in the range of 77 to 89 %. The optical band gap calculated from the absorption coefficient of transmittance spectra was around 3.9 eV. The negative sign of Hall coefficient confirmed the films were n-type conducting. The bulk resistivity increased from 2.26 ×10-3 to 4.08 ×10-1Ω -cm for the increase in OVP from 1.4 to 4.1 %, and thereafter increased dramatically so as the Hall coefficients were not detectable. From the AFM morphologies it is evaluated that the RMS roughness of the films ranges from 0.9 to 3.2 nm.
INTRODUCTION An important application of thin film technology is the fabrication of transparent thin film transistors (TTFTs) [1]. The challenging prerequisite for this is to develop transparent and conducting oxides (TCOs) that serve also as an active element [2]. These TCOs are also being employed successfully in solar cells, stable resistors, touch-sensitive switches, digital displays, electro-chromic displays and gas sensors. Novel materials are being tried out apart from the conventional TCOs based on tin oxide, zinc oxide and indium tin oxide to improve the device performance [3]. Although, the recently developed high mobility molybdenum- doped indium oxide (IMO) [4-7] is very attractive it requires further research especially regarding processing at room temperature. Toward achieving this, IMO thin films rf sputtered onto glass substrates at room temperature are reported in this study.
EXPERIMENTAL DETAILS All the films were sputtered from an In2O3 (95 wt. %): Mo (5 wt. %) target (2″ diameter) at a constant power mode of 100 W onto glass substrates (100 ×100 ×1 mm3). Partial pressure of oxygen varied from 1.9 ×10-5 to 2.0 ×10-4 mbar with flow between 0.5 and 3.0 sccm, whereas,
argon partial pressure was fixed at ~1.5 ×10-3 mbar (20 sccm). The pressure was maintained at ~1.7 ×10-3 mbar during sputtering. The sputtering parameters that we have optimized for zinc doped indium oxide films in our previous study [8] were maintained for sputt
Data Loading...
