Burag Yaglioglu

High-mobility amorphous In2O3–10wt%ZnO thin film transistors

The authors report on the fabrication and characterization of thin film transistors that use sputter deposited amorphous indium zinc oxide both for the channel and source-drain metallizations in a gate-down configuration. The channel and source-drain layers were deposited from a single In2O3–10wt%ZnO ceramic target using dc magnetron sputtering onto an unheated substrate. The carrier densities in the channel (2.1×1017∕cm3) and source/drain regions (3.3×1020∕cm3) were adjusted by changing the reactive oxygen content in the sputter chamber during deposition. The resulting transistors operate as depletion mode n-channel field effect devices with saturation mobility of 20cm2∕Vs and on/off current ratio of 108.

Crystallization of amorphous In2O3–10 wt % ZnO thin films annealed in air

We report on the crystallization of amorphous indium zinc oxide (a-IZO) with stoichiometry of In2Zn0.38O3.38 (In2O3–10 wt % ZnO) thin films deposited by dc magnetron sputtering. Transmission electron microscopy and glancing incidence x-ray diffraction were used to show that, when annealed in air at 500 °C, the product of a-IZO thin film crystallization is a compositionally modulated crystal of high-pressure corundum In2O3 phase. The composition, microstructure, resistivity, carrier density, and mobility of this new IZO phase are reported and are compared to the bixbyite ITO (In2O3–9.8wt%SnO2) deposited and annealed under identical conditions.

Characterization of TCO Materials

The full array of microstructural, optical, and electrical materials characterization tools are used in the development of materials and processes for TCO applications. Most of these characterization tools are well described in other sources and are widely applied in the semiconductor and oxide fields of research. In this chapter, discussion is limited to a few of the methods used for characterizing the relationship between microstructure and electrical transport properties in transparent conducting materials particularly those that are based on the amorphous and crystalline oxides of In2O3, SnO2, and ZnO. These materials are currently of greatest practical importance for passive transparent electrode applications and they form the basis for the emerging field of oxide thin film transistor electronics.

A Structural Study of the Amorphous to Crystalline Transformation in In 2 O 3 Thin Films

We have investigated the structure of sputter deposited amorphous and crystalline indium oxide films by electron diffraction. Selected area diffraction patterns were recorded for both states from which radial density functions were derived. The comparison of the crystalline radial density function to the amorphous one shows that the first nearest neighbor distance corresponding to the In-O bond length is 2.2A and is the same for both states. A model density function for crystalline structure was used to explore the difference in higher order peak positions. We report that the In-In separation in amorphous state has a single characteristic distance of 3.6A compared to the crystalline state which has two non-equivalent In sites and consequently different separations as In(1)-In(2) at 3.4A and In(2)-In(2) at 4.3A.