ICMCTF2000 Session C3-2: Structure/Property Relationships

Tuesday, April 11, 2000 1:30 PM in Room Sunset

Tuesday Afternoon

Start	Invited?	Item
1:30 PM		C3-2-1 Thickness Dependence of Optical Properties of Metallic Films L.A. Udachan, S. RamaRao (Sharanabasaveshwar College of Science, India) Present day technology needs several types of Thin Films for a variety of applications. There occurs many deposition parameters which govern physical properties of metallic films. Amongst them, thickness is the most important deposition parameter which dictates all the characteristics of metallic films to a large extent. So, we have selected here Chromium and Tin in order to study their optical behaviour in the Ultra Violet and Visible regions of electromagnetic radiation as they exhibit contradictory properties in the bulk form. Chromium in the bulk form has a high melting point with negative temperature coefficient of resistance. On the other hand Tin has low melting point in the bulk form with a positive temperature coefficient of resistance. A comparative study on the optical properties of these metals yield a wealth of information about the electronic band structure of metallic films, binding energy, impurities and defects. From the knoweldge of reflection, absorption and transmission coefficients it is possible to evaluate index of defraction and band gap. A detailed discussion will be made about the origin of optical constants, magnitudes and how they depend on the deposition parameters. A correlation can be made with the data that obtained from transport studies and inference can be drawn. Acknowlegement : We thank the Department of Science and Technology, Government of India, New Delhi, for the financial support.
1:50 PM		C3-2-2 Optical and Structural Properties of Highly C-axis Oriented Aluminum Nitride Prepared by Sputter-deposition in Pure Nitrogen T.P. Drüsedau, J. Bläsing (Otto-von-Guericke Universität Magdeburg, Germany) Nanocrystalline aluminum nitride films of 70 to 1400 nm thickness were prepared by rf-magnetron sputtering from an Al-target. For the first time, the influence of the pressure on the film properties was investigated for sputter-deposition in pure nitrogen-atmosphere. The Deposition rate decreases with pressure from 0.35 to 0.17 nm. The films prepared at a substrate temperature of 540 K show around 1 Pa a maximum of the (x-ray) surface roughness and the crystallite size, which amount to 5 nm and 30 nm, respectively. In addition, the surface topography is investigated by atomic force microscopy. The optical properties static refractive index and optical Tauc gap depend weakly on the pressure and are in average 2.0 and 5.0 eV, respectively. Highly strained crystallites grow at pressures below 0.5 Pa. The films are (excepted sputtering above 2 Pa) in general highly c-axis oriented. The bombardment of the growing AlN by energetic nitrogen neutrals originating from reflection at the target, which was simulated by TRIM.SP Monte-Carlo calculations, is suggested to be the general origin of the preferred c-axis growth of sputter-deposited films.
2:10 PM		C3-2-3 Investigation of Optical and Structural Properties of Sputter Deposited ZrO₂ R. Erz, S. McEldowney, P. LeFebvre, T. Allen (Optical Coating Laboratory, Inc.) ZrO2 is a commonly used high index material for production of thin film optical filters. This is due to its high transparency from the ultraviolet to the near infrared wavelengths and its relatively low scatter. Both sputtered and evaporated ZrO2 layers exhibit complex changes in the microstructure during growth which manifest themselves as changes in optical properties (n, k, inhomogenity ) and stress. ZrO2 single layers and ZrO2/SiO2 designs deposited using reactive magnetron sputtering using OCLI’s MetaMode® sputtering apparatus were studied using optical modeling and ellipsometry. ZrO2 refractive index and stress were found to be functions of layer thickness and sputtering process parameters (working gas flow and target power). Results were used to improve the spectral performance and stress of multilayer ZrO2/SiO2 coatings.