Nanoscale surface electrical properties of indium–tin–oxide films for organic light emitting diodes investigated by conducting atomic force microscopy

Abstract

Articles you may be interested inWork-function changes of treated indium-tin-oxide films for organic light-emitting diodes investigated using scanning surface-potential microscopy J. Appl. Phys. 97, 073713 (2005); 10.1063/1.1884245Highly oriented indium tin oxide films for high efficiency organic light-emitting diodes Nanoscale surface electrical properties of indium-tin-oxide films prepared by different cleaning methods for use as anode materials in organic light emitting diodes are studied by conducting atomic force microscopy. It is found that most of the surface area possesses a nonconducting feature, and an ultraviolet-ozone treatment produces the most nonconductive sample. The conducting regions, which distribute randomly and range from 6 to 50 nm in size, are attributed to the existence of Sn-rich oxide by a comparison with reported scanning electron microscopy images. After scanning the tip with a bias of Ϫ8 V on the nonconducting regions, oxide decomposition occurs on as-received and wet-cleaning processed samples, whereas no structure change appears on the ozone treated sample. The results indicate that the generation of stable oxide after ozone treatment is one of the origins for improved device performance.

Nanoscale electrical properties of ZnO nanorods grown by chemical bath deposition

“…Such a relationship is expected for unipolar memory behavior, and these regions are called recordable regions. However, in the regions where the current was less than 5 nA, the Fowler‐Nordheim electron tunneling mechanism (Chen et al, ; Lin et al, ) shown in Figure c was responsible for the detected current, and the turn‐on voltage was higher than 4 V; these regions are called insulating regions. The coverage percentages of these three regions, which are presented in Figure , were determined using the current distribution histograms of the current images in Figure .…”

“…The tips were precoated with a Cr layer and subsequently coated with a 20 nm PtIr film by ion sputtering. The CAFM and SSPM procedures employed in this study have been previously described (Chen, ; Chen et al, ; Lin et al, ; Yu et al, ). The current–voltage ( I – V ) curves and current maps were measured by applying a positive voltage to the tip while the substrate was grounded.…”

“…The surface morphology and section depth of ZNAs were measured and analyzed using atomic force microscopy (AFM) and field‐emission scanning electron microscopy (FESEM). Conducting atomic force microscopy (CAFM) (Chen et al, ; Lin, Chen, Perng, & Chen ; Yu et al, ), and scanning surface potential microscopy (SSPM) (Chen, ) were used to measure the electrical properties of ZNAs. A conductive probe was used as the top electrode, and the local contact current and work function (WF) of ZNAs were integrally analyzed and discussed.…”

Dependence of the current and power efficiencies of organic light-emitting diode on the thickness of the constituent organic layers

“…The sequence of pre-cleaning prior to loading into the evaporation chamber consisted of soaking in ultra-sonic detergent for 30 min, spraying with de-ionized (DI) water for 10 min, soaking in ultrasonic DI water for 30 min, oven bake-dry for 1-2 h, and ITO surface stabilizing ultraviolet ozone illumination [19] for 9 min.…”

Differences in the nanoscale electrical properties of GaN films grown on sapphire and ZnO substrates by molecular beam epitaxy

“…In this study, GaN films were grown using molecular beam epitaxy (MBE) on two different substrates, ZnO and sapphire. Atomic force microscopy (AFM), conducting atomic force microscopy (CAFM) (Chen, Hou, Hsieh, Chang, & Chen, ; Chen et al, ; Lin, Chen, Perng, & Chen, ; Yu et al, ), and scanning surface potential microscopy (SSPM) (Chen, ; Chen et al, ) were utilized to integrally study and analyse the differences in surface structure, contact current distribution, and work function (WF) distribution of the films. Differences in these microphysical characteristics could seriously affect the function and efficiency of GaN‐based components because they may result in the redistribution of the charges inside the GaN semiconductor, which form the built‐in electric field, while the quantum‐confined Stark effect could accelerate charge accumulation.…”