Hydrogen plasma treatment for improved conductivity in amorphous aluminum doped zinc tin oxide thin films

Improving the conductivity of earth-abundant transparent conductive oxides (TCOs) remains an important challenge that will facilitate the replacement of indium-based TCOs. Here, we show that a hydrogen (H-2)-plasma post-deposition treatment improves the conductivity of amorphous aluminum-doped zinc tin oxide while retaining its low optical absorption. We found that the H-2-plasma treatment performed at a substrate temperature of 50 degrees C reduces the resistivity of the films by 57% and increases the absorptance by only 2%. Additionally, the low substrate temperature delays the known formation of tin particles with the plasma and it allows the application of the process to temperature-sensitive substrates. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License

What Limits Mobility in Hydrogenated Indium Oxide?

Understanding the electron scattering mechanisms dominating transport in high and low mobility transparent conducting oxides can provide insight into improving the properties of this crucial photovoltaic device layer. Contributions from ionized impurity scattering, phonon scattering, and grain boundary scattering were measured and quantified in hydrogenated indium oxide thin films, which had varying composition and grain size, resulting in a wide range of carrier densities (similar to 10(18) cm(-3) - similar to 10(20) cm(-3)) and carrier mobilities (similar to 10 cm(2)/Vs - >100 cm(2)/Vs). We used temperature-dependent Hall measurements from 5-300 Kelvin to characterize electrical properties of the sputtered films. Grain boundary scattering dominated films with the lowest mobility, whereas films with >100 cm(2)/Vs mobilities were dominated by contributions from ionized impurity scattering and polar optical phonon scattering

An Indium-Free Anode for Large-Area Flexible OLEDs: Defect-Free Transparent Conductive Zinc Tin Oxide

Flexible large-area organic light-emitting diodes (OLEDs) require highly conductive and transparent anodes for efficient and uniform light emission. Tin-doped indium oxide (ITO) is the standard anode in industry. However, due to the scarcity of indium, alternative anodes that eliminate its use are highly desired. Here an indium-free anode is developed by a combinatorial study of zinc oxide (ZnO) and tin oxide (SnO2), both composed of earth-abundant elements. The optimized Zn-Sn-O (ZTO) films have electron mobilities of up to 21 cm(2) V-1 s(-1), a conductivity of 245 S cm(-1), and <5% absorptance in the visible range of the spectrum. The high electron mobilities and low surface roughness (<0.2 nm) are achieved by producing dense and void-free amorphous layers as confirmed by transmission electron microscopy. These ZTO layers are evaluated for OLEDs in two anode configurations: i) 10 cm(2) devices with ZTO/Ag/ZTO and ii) 41 cm(2) devices with ZTO plus a metal grid. The ZTO layers are compatible with OLED processing steps and large-area white OLEDs fabricated with the ZTO/grid anode show better performance than those with ITO/grid anodes. These results confirm that ZTO has the potential as an In-free and Earth-abundant alternative to ITO for large-area flexible OLEDs