Substrate temperature influenced physical properties of silicon MOS devices with TiO2 gate dielectric |
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Authors: | M. Chandra Sekhar P. Kondaiah S. V. Jagadeesh Chandra G. Mohan Rao S. Uthanna |
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Affiliation: | 1. Department of Physics, Sri Venkateswara University, , Tirupati, 517 502 India;2. CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Technologia, FCT, Universidade Nova de Lisboa and CEMOP/UNINOVA, , 2829‐516 Caparica, Portugal;3. Department of Instrumentation and Applied Physics, Indian Institute of Science, , Bangalore, 560 012 India |
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Abstract: | DC reactive magnetron sputtering technique was employed for deposition of titanium dioxide (TiO2) films. The films were formed on Corning glass and p‐Si (100) substrates by sputtering of titanium target in an oxygen partial pressure of 6×10?2 Pa and at different substrate temperatures in the range 303 – 673 K. The films formed at 303 K were X‐ray amorphous whereas those deposited at substrate temperatures ≥ 473 K were transformed into polycrystalline nature with anatase phase of TiO2. Fourier transform infrared spectroscopic studies confirmed the presence of characteristic bonding configuration of TiO2. The surface morphology of the films was significantly influenced by the substrate temperature. MOS capacitor with Al/TiO2/p‐Si sandwich structure was fabricated and performed current–voltage and capacitance–voltage characteristics. At an applied gate voltage of 1.5 V, the leakage current density of the device decreased from 1.8 × 10?6 to 5.4 × 10?8 A/cm2 with the increase of substrate temperature from 303 to 673 K. The electrical conduction in the MOS structure was more predominant with Schottky emission and Fowler‐Nordheim conduction. The dielectric constant (at 1 MHz) of the films increased from 6 to 20 with increase of substrate temperature. The optical band gap of the films increased from 3.50 to 3.56 eV and refractive index from 2.20 to 2.37 with the increase of substrate temperature from 303 to 673 K. Copyright © 2012 John Wiley & Sons, Ltd. |
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Keywords: | titanium dioxide MOS capacitor leakage current dielectric optical properties |
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