Photoferroelectric Nanowires

The presented in (Gruverman & Kholkin, 2006; Scott, 2006) advances in the quickly developing field of nanoscale ferroelectrics are made because they are important for many applications as well as for the fundamental physics questions. This review summarizes results of investigations of nanowires of antimony sulfoiodide (SbSI) -type materials (i.e. SbSI, antimony selenoiodide (SbSeI), and antimony sulfoselenoiodide (SbSxSe1-xI)). This class of materials represents the semiconducting ferroelectrics (Fridkin, 1980; Gerzanich et al., 1982; Dittrich et al., 2000) known also as photoferroelectrics (Fridkin, 1979). Since photons in a semiconductor generate excess free carriers, and induce a change of its electronic state, one may observe a lot of interesting phenomena in these materials. Obviously, the presented new materials as the other one-dimensional semiconductor nanostructures (Xia et al., 2003) should receive considerable attention from the scientific and engineering communities due to their potentially useful novel electronic and optical properties. The first description of the synthesis of SbSI was given almost two centuries ago (Henry & Garot, 1824) but the crystal structure of this and the other ternary chalcohalides formed from the group 15-16-17 elements was established much later (Dönges, 1950). However, the intensive investigation of SbSI started after discoveries of its photoconductivity (Nitsche & Merz, 1960) and its ferroelectric properties (Fatuzzo et al., 1962). An unusually large number of interesting properties of SbSI has been found. Among them there are the pyroeletric, pyro-optic, piezoeletric, electromechanical, electrooptic and nonlinear optical effects. Due to these properties it is an attractive and suitable material for thermal imaging, light modulator, ferroelectric field effect transistor, gas sensors, piezoelectric elements used in certain types of electromechanical sensors and actuators, temperature auto stabilized nonlinear dielectric elements (TANDEL), time-controlling devices and other applications (see e.g. Refs. in (Nowak et al., 2008; Nowak et al., 2009d). The SbSI is also taken into consideration as a valuable material for photonic crystals (see Refs. in (Nowak et al., 2008)). It should be noted that quaternary compounds formed as solid solutions from the group 1516-17 elements possess additional very interesting feature: their energy band gaps and physical properties are tailored with stoichiometric composition. For example, in SbS1-xSexI mixed crystals the strong monotonous decrease of the Curie temperature with the increase of Se content had been observed (Nitsche et al., 1964). Being a promising material with potential applications, SbSI-type materials were synthesized in a variety of ways and prepared in different forms: bulk crystals, polycrystalline samples, ceramics, and thin-films (see e.g. Refs. in (Nowak et al., 2008;