Elsevier

Applied Surface Science

Volume 257, Issue 17, 15 June 2011, Pages 7665-7670
Applied Surface Science

Effect of substrate temperature and oxygen partial pressure on microstructure and optical properties of pulsed laser deposited yttrium oxide thin films

https://doi.org/10.1016/j.apsusc.2011.03.156Get rights and content

Abstract

Yttrium oxide thin films were deposited on Si (1 1 1) and quartz substrates by pulsed laser deposition technique at different substrate temperature and oxygen partial pressure. XRD analysis shows that crystallite size of the yttrium oxide thin films increases as the substrate temperature increases from 300 to 873 K. However the films deposited at constant substrate temperature with variable oxygen partial pressure show opposite effect on the crystallite size. Band gap energies determined from UV–visible spectroscopy indicated higher values than that of the reported bulk value.

Highlights

► The microstructural and optical properties of yttria films as a function of wide substrate temperature and oxygen partial pressure range have been reported for the first time for the films prepared by pulsed laser deposition. ► The X-ray diffraction results indicated that the films were polycrystalline yttria films with (2 2 2) preferred orientation. ► Yttria thin films have good transparency of ∼90% in the wavelength range of 400–800 nm for the films deposited at 873 K and 0.2 Pa oxygen partial pressure. ► The band gap increases with increase in substrate temperature and decrease with increase in oxygen partial pressure as a consequence of increasing crystallite size.

Introduction

Yttrium oxide thin films have received much attraction due to its important technological application and excellent mechanical, optical, thermal and electrical properties. It has physical properties like a well-matched lattice constant with Si (ayttrium oxide  2 × aSi) [1], [2], [3], relatively high dielectric constant (∼17) [4], high melting point (∼2956 K) [5], [6], high refractive index (∼2) [7], high mechanical strength [8] and wide energy band gap (∼5.6 eV)[9].

Yttrium oxide thin films have found important applications such as dielectric layers in electroluminescent devices [9], [10], complementary metal-oxide-semiconductor devices [1], [2], high-density dynamic random access memory [9], [11] and electrochemical sensors [12]. It is an important material for optical application due to its wide band gap and its ability to be a host material for rare earth ions [1], [13], [14], [15], [16], [17], [18].

Yttrium oxide thin films have been prepared by different methods like pulsed liquid injection plasma enhanced metal organic chemical vapour deposition [13], plasma–enhanced chemical vapour deposition [19], ion beam sputtering [20], thermal decomposition [21], radio frequency sputtering [10], [12], [22], electron beam evaporation [23], [24], ultra violet–assisted pulsed laser deposition [25] and pulsed laser deposition (PLD) [1], [9]. Among all these techniques PLD is an attractive deposition technique because it involves simple experimental operation, preserves good film stoichiometry, provides energetic flux, and allows the easy addition of various gases during the deposition process.

In the present work yttrium oxide thin films were deposited on Si (1 1 1) and quartz substrates at different substrate temperatures (from 300 to 873 K) and oxygen partial pressures (2–0.002 Pa) with the aim of optimizing the process parameters to tailor the desired optical properties. The effect of these parameters on the crystallite size, lattice parameter and optical properties (transmittance, optical band gap and refractive index) was examined by X-ray diffraction, ultraviolet–visible (UV–vis) spectroscopy, scanning electron microscopy, atomic force microscopy and Raman spectroscopy techniques.

Section snippets

Experimental procedure

A target was prepared using commercially available yttrium oxide powder of 99.99% purity. For target preparation, yttrium oxide powder was fine ground and compacted to a pellet of 20 mm diameter and 3 mm thick by applying 100 kN pressure. The pellet was sintered at 1723 K for 4 h. The pellet had a sintered density ∼90% and was found to be yttrium oxide with cubic phase in agreement with JCPDS file (#41-1105). Si (1 1 1) and quartz substrates were ultrasonically cleaned with soap solution, water and

X-ray analysis

Fig. 1 shows the XRD pattern of the sintered yttria pellet used as a target to deposit yttria thin films. It was found to be a phase pure yttria having cubic structure (JCPDS file no 41-1105). Raman analysis of the yttria target is also carried out, which supports the XRD results (Fig. 2(a)) as well as the Raman study reported in Ref. [26] for a single crystal of yttria. Though peak positions of the vibrational modes remain the same in the present study and Ref. [26], there is a variation in

Conclusions

The effect of substrate temperature and oxygen partial pressure on the microstructure and optical properties of yttrium oxide thin films prepared by pulsed laser deposition has been investigated. It is found that the crystallinity of yttrium oxide thin films is highly dependent on process parameters. The X-ray diffraction analysis shows an increase in the crystallite size of films with increase in the substrate temperature, where as oxygen partial pressure shows an opposite effect on the

Acknowledgements

We thank Smt. Jyothi and Mr. R Thirumurugesan for x-ray analysis, Smt. M. Radhika for SEM analysis and Dr. T. R. Ravindran for Raman analysis. We also thank Dr. M. Vijayalakshmi, AD, PMg, Dr. T. Jayakumar, Director, MMG and Dr. Baldev Raj, Director, IGCAR for their support and encouragement.

References (41)

  • R.J. Gaboriaud et al.

    Appl. Surf. Sci.

    (2002)
  • Y. Guyot et al.

    Opt. Mater.

    (1996)
  • R. Ivanic et al.

    Vacuum

    (2001)
  • Ph. Lecoeur et al.

    Appl. Surf. Sci.

    (2002)
  • A. Peeva et al.

    Appl. Surf. Sci.

    (2007)
  • P.B.W. Burmester et al.

    Mater. Sci. Eng. B

    (2003)
  • M. Jublot et al.

    Thin Solid Films

    (2007)
  • A. Ohta et al.

    Microelectron. Eng.

    (2004)
  • W.M. Cranton et al.

    Thin Solid Films

    (1993)
  • R.N. Sharma et al.

    Electron. Opt.

    (1991)
  • Y. repelin et al.

    J. Solid State Chem.

    (1995)
  • X.M. Fan et al.

    Appl. Surf. Sci.

    (2005)
  • Y. Du et al.

    J. Eur. Ceram. Soc.

    (2001)
  • Z.G. Zhang et al.

    Physica E

    (2007)
  • M. Liu et al.

    Mater. Chem. Phys.

    (2008)
  • D. Beena et al.

    Appl. Surf. Sci.

    (2009)
  • C. Yang et al.

    J. Cryst. Growth

    (2010)
  • K.J. Lethy et al.

    Appl. Surf. Sci.

    (2008)
  • Xuerui Cheng et al.

    Physica B

    (2009)
  • G.D. Wilk et al.

    J. Appl. Phys.

    (2001)
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