Structural optical and electrical properties of a transparent conductive ITO/Al-Ag/ITO multilayer contact.

Aliyu Kabiru Isiyaku,Aliyu Kabiru Isiyaku,Nafarizal Nayan,Ahmad Hadi Ali

doi:10.3762/bjnano.11.57

Aliyu Kabiru Isiyaku, Aliyu Kabiru Isiyaku + Show 2 more

Open Access

https://doi.org/10.3762/bjnano.11.57

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Abstract

Indium tin oxide (ITO) is a widely used material for transparent conductive oxide (TCO) films due to its good optical and electrical properties. Improving the optoelectronic properties of ITO films with reduced thickness is crucial and quite challenging. ITO-based multilayer films with an aluminium–silver (Al–Ag) interlayer (ITO/Al–Ag/ITO) and a pure ITO layer (as reference) were prepared by RF and DC sputtering. The microstructural, optical and electrical properties of the ITO/Al–Ag/ITO (IAAI) films were investigated before and after annealing at 400 °C. X-ray diffraction measurements show that the insertion of the Al–Ag intermediate bilayer led to the crystallization of an Ag interlayer even at the as-deposited stage. Peaks attributed to ITO(222), Ag(111) and Al(200) were observed after annealing, indicating an enhancement in crystallinity of the multilayer films. The annealed IAAI film exhibited a remarkable improvement in optical transmittance (86.1%) with a very low sheet resistance of 2.93 Ω/sq. The carrier concentration increased more than twice when the Al–Ag layer was inserted between the ITO layers. The figure of merit of the IAAI multilayer contact has been found to be high at 76.4 × 10−3 Ω−1 compared to a pure ITO contact (69.4 × 10−3 Ω−1). These highly conductive and transparent ITO films with Al–Ag interlayer can be a promising contact for low-resistance optoelectronics devices.

Highlights

Transparent conducting oxides (TCO) thin films have been receiving much attention regarding their use as contacts in several optoelectronic devices such as LEDs [1], solar cells [2] and flat panel displays [3]
The increase in transmittance is attributed to the improvement of the crystallinity of both the Indium tin oxide (ITO) film and the metal interlayer after annealing, which resulted in less light as-deposited IAAI film
ITO/Al-Ag/ITO (IAAI) multilayer films were deposited by radio frequency (RF) and direct current (DC) magnetron sputtering at room temperature

Summary

Introduction

Transparent conducting oxides (TCO) thin films have been receiving much attention regarding their use as contacts in several optoelectronic devices such as LEDs [1], solar cells [2] and flat panel displays [3]. The quality of both metal and ITO layers determines the optical and electrical performance of the multilayer structures [4]. The low resistivity and relatively high transmittance (compared to other metals) in the visible region of Ag thin films at room temperature led to the wide use of Ag layers in ITO multilayer contacts [21,22,23,24].

Results

Conclusion