Tin doped indium oxide (ITO) films are highly transparent in the visible region, exhibiting high reflectance in the infrared region, and having nearly metallic conductivity. Owing to this unusual combination of electrical and optical properties, this material is widely applied in optoelectronic devices. The association of these properties in a single material explains the vast domain of its applicability and the diverse production methods which have emerged. Although the different properties of tin doped indium oxide in the film form are interdependent, this article mainly focuses on the electrical aspects. Detailed description of the conduction mechanism and the main parameters that control the conductivity is presented. On account of the large varieties and differences in the fabrication techniques, the electrical properties of ITO films are discussed and compared within each technique.

/pdf/tin-doped-indium-oxide-thin-films-electrical-properties-1emmfeswwg.pdf

Tin doped indium oxide thin films: Electrical properties

As a first step in the identification of suitable alternative gate dielectrics for metal oxide semiconductor field-effect transistors (MOSFETs), we have used tabulated thermodynamic data to comprehensively assess the thermodynamic stability of binary oxides and nitrides in contact with silicon at temperatures from 300 K to 1600 K. Sufficient data exist to conclude that the vast majority of binary oxides and nitrides are thermodynamically unstable in contact with silicon. The dielectrics that remain are candidate materials for alternative gate dielectrics. Of these remaining candidates, the oxides have a significantly higher dielectric constant (ĸ) than the nitrides. We then extend this thermodynamic approach to multicomponent oxides comprising the candidate binary oxides. The result is a relatively small number of silicon-compatible gate dielectric materials with ĸ values substantially greater than that of SiO2 and optical bandgaps ≥ eV.

A Thermodynamic Approach to Selecting Alternative Gate Dielectrics

Origin of characteristic grain-subgrain structure of tin-doped indium oxide films

This year marks a major materials milestone in the makeup of silicon-based fieldeffect transistors: in the microprocessors produced by leading manufacturers, the SiO 2 gate dielectric is being replaced by a hafnium-based dielectric. The incredible electronic properties of the SiO 2 /silicon interface are the reason that silicon has dominated the semiconductor industry and helped it grow to over $250 billion in annual sales, as reported by the Semicoriductor Industry Association (SIA), San Jose, CA. The shrinkage of transistor dimensions (Moore's law) has led to tremendous improvements in circuit speed and computer performance. At the same time, however, it has also led to exponential growth in the static power consumption of transistors due to quantum mechanical tunneling through an ever-thinner SiO 2 gate dielectric. This has spurred an intensive effort to find an alternative to SiO 2 with a higher dielectric constant (K) to temper this exploding power consumption. This article reviews the high-K materials revolution that is enabling Moore's law to continue beyond SiO 2 .

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0883769400006333

Gate Oxides Beyond SiO2

Brick layer models (BLMs), although applicable at the microscale, are inappropriate for characterizing electroceramics at the nanoscale A new construct, the nano-grain composite model (n-GCM), has been developed to model/analyze the AC-impedance response of equiaxed polycrystalline electroceramics The procedure employs a set of equations, based on the Maxwell–Wagner/Hashin–Shtrikman effective medium model, to calculate local electrical properties (conductivity, dielectric constant) for both “phases” (grain core, grain boundary) from experimental AC-impedance spectra and also, for the first time, grain core volume fraction The n-GCM method was tested on a model system (a 3D-BLM material) and demonstrated with a test case (nanograined yttria-stabilized zirconia) The method appears to be applicable only at nanograin sizes, ie, 10–100 nm Limitations of the method, in terms of grain size (10–100 nm) and experimental uncertainty, are also discussed

The Brick Layer Model Revisited: Introducing the Nano-Grain Composite Model

The effects of temperature (4–400 K), hydrostatic pressure and frequency on the dielectric constant, e’, and dielectric loss of single crystals of LaAlO3 and cubic yttria(9.5 mol %)‐stabilized zirconia (ZrO2) were investigated. Both crystals are relatively low‐loss, low‐dispersion dielectrics in the temperature range (T<150 K) of most interest for high‐temperature superconductors. The pressure results make it possible to evaluate the various contributions to the temperature dependence of e’. It is found that this dependence is dominated by the change of polarizability with volume. The dielectric properties of the two crystals are compared with those of other candidate substrate materials.

G. A. Samara

Papers

Low‐temperature dielectric properties of candidate substrates for high‐temperature superconductors: LaAlO3 and ZrO2 : 9.5 mol % Y2O3