Spectroscopic ellipsometry applied to phase transitions in solids: possibilities and limitations

Abstract

The possibilities of in situ spectroscopic ellipsometry applied to phase transitions investigation in oxide thin films and crystals are examined in this work, along with the use of various parameters calculated from ellipsometric data (band gap energy Eg, refractive index n and surface roughness) together with the directly measured main ellipsometric angles psi and Delta, for the detection of phase transitions. The efficiency of spectroscopic ellipsometry on "surface" phase transition and its sensitivity to surface defects are also demonstrated.

Compositional and Optical Gradient in Films of PbZrxTi1-xO3 (PZT) Family

“…SE has long been recognized as a powerful method for the characterization of thin films and their inhomogeneity. It has already been applied to refractive index depth profile studies of oxynitride SiO 2 N x films (Callard et al, 1998;Nguyen et al, 1996;Snyder et al, 1992;Rivory, 1998;) (additionally confirmed by chemical etching (Callard et al, 1998)), lead silicate glass (Trolier-McKinstry and Koh, 1998), oxidized copper layers (Nishizawa et al, 2004), polymers (Guenther et al, 2002), semiconductor indium tin oxide (ITO) films (Losurdo, 2004;Morton et al, 2002), sol-gel PZT thin films (Aulika et al, 2009) confirmed by TEM and EDX, and RF-sputtered self-polarized PZT thin films , and was confirmed by discharge optical emission spectroscopy (GD-OES) and pyroelectric profile measurements by the laser intensity-modulation method (LIMM) (Deineka et al, January, 2001;Suchaneck et al, 2002). SE has also been applied to the study of ion implantation depth profiles in silicon wafers and confirmed by RBS (Boher et al, 1996;Fried et al, 2004).…”

“…This technique does not require a large size of the sample; it is enough to have a size of ~ 5×5 mm. In situ spectral ellipsometry studies allow detecting phase transition in thin films and surfaces (Dejneka et al, 2009), as well as of the interface what is very important for thin film and crystal studies. For advanced optoelectronics and bandgap engineering applications is important to investigate the relationship between the microstructure, sample preparation conditions & optical properties.…”

“…For advanced optoelectronics and bandgap engineering applications is important to investigate the relationship between the microstructure, sample preparation conditions & optical properties. SE gives opportunity to detect technologically and scientifically important properties of thin films such as optical bang gap (Dejneka et al, 2010), thermooptical properties (Aulika et al, 2007 and2009;Dejneka et al, 2009), and optical gradient (Aulika et al, 2008 and2009;Deineka et al, January, 2001). …”

“…for the deposition of sol-gel films is influential in controlling the homogeneity of the films. Recently detailed studies of sol-gel PZT 52/48 thin and thick films were presented (Aulika et al, 2009), which were made by using two different solvent systems: a mixture of acetic acid and methanol (AcOH/MeOH) or 2-Methoxyethanol (2-MEO) (Fig. 8, Case 4 and 5).…”

“…The annealing time was sufficient for all films to crystallize. Among all analyzed samples, the refractive index gradient was found only for two groups of films, which were made by crystallizing each layer before another layer was deposited (LCI) (Aulika et al, 2009): 1) One group of films was made using the AcOH/MeOH sol ( Fig. 9a) and 2) the other group was made with the 2-MEO sol (Fig.…”