Fabrication of Nanopillar Crystalline ITO Thin Films with High Transmittance and IR Reflectance by RF Magnetron Sputtering

Abstract

Nanopillar crystalline indium tin oxide (ITO) thin films were deposited on soda-lime glass substrates by radio frequency (RF) magnetron sputtering under the power levels of 100 W, 150 W, 200 W and 250 W. The preparation process of thin films is divided into two steps, firstly, sputtering a very thin and granular crystalline film at the bottom, and then sputtering a nanopillar crystalline film above the bottom film. The structure, morphology, optical and electrical properties of the nanopillar crystalline ITO thin films were investigated. From X-ray diffraction (XRD) analysis, the nanopillar crystalline thin films shows (400) preferred orientation. Due to the effect of the bottom granular grains, the crystallinity of the nanopillar crystals on the upper layer was greatly improved. The nanopillar crystalline ITO thin films exhibited excellent electrical properties, enhanced visible light transmittance and a highly infrared reflectivity in the mid-infrared region. It is noted that the thin film deposited at 200 W showed the best combination of optical and electrical performance, with resistivity of 1.44 × 10−4 Ω cm, average transmittance of 88.49% (with a film thickness of 1031 nm) and IR reflectivity reaching 89.18%.

Air Annealing Effect on Oxygen Vacancy Defects in Al-doped ZnO Films Grown by High-Speed Atmospheric Atomic Layer Deposition

“…TCOs have attracted lots of attention because they show simultaneously conductivity and optical transparency. In the past fifty years, indium tin oxide (ITO) has become the most widely used TCO for optoelectronic devices due to its high transmittance of~90% in the visible range and low resistivity (~2 × 10 −4 Ω-cm) with mobility of about 40 cm 2 /Vs and high carrier concentration of 10 21 cm −3 [8,9]. However, ITO faces several challenges.…”

Tuning the optical and electrical properties of HiPIMS-ITO films by variation of annealing temperature

“…In addition, a highest diffraction peak (222) of the ITO film is observed, which indicates that it is preferentially oriented in the <111> plane. Several research groups have reported that the (222) diffraction peak and (400) diffraction peak, the <100> plane, are related to the oxygen content [10][11][12]. They point out that the <111> plane can accommodate more oxygen atoms, while the <100> plane can accommodate more oxygen vacancies.…”

Solution-Processed Multistacked Tin-Doped Indium Oxide Nanoparticle Conductors for Cost-Effective Thin Film Heaters

“…Moreover, it shows completely different surface properties from sputtered ITO grown in multistructured nanopillar crystals; ITO NPs show different surface and cross-sectional morphologies by agglomeration of nanoparticles after heat treatment. 34 In general, the high optical transmittance of a thin film is mainly related to smooth surface roughness, small crystal size, good uniformity, and low refractive index. 45 In particular, an increase in crystallinity due to an external energy source greatly affects the optical and electrical properties.…”

“…Recently, our group has also studied various materials, such as the AgNW network, self-assembled network, W-doped In 2 O 3 , and MoO 3 –Ag–MoO 3 . − Despite the high electrical and thermal conductivities of AgNW, AgNW-based transparent conductors are easily oxidized in air, have low heat and oxidation resistance, and have a rough surface. , Furthermore, TFH electrode materials were studied through a large-area roll-to-roll process with CuO x –Cu–CuO x , InZnSiO–Ag–InZnSiO, ZnSnO–AgPdCu–ZnSnO, ITO–Cu–ITO, and ITO–Ag–ITO. − Although nanoparticle-based oxide electrode such, as InZnO, InZnSnO, InTiO, and InSnO has been reported, − research into solution-based ITO conductors and solution-multilayers for transparent TFHs is still insufficient. Specifically, studies on the crystallinity, preferred orientation, and electrical and optical properties depending on the thickness of the sputtered ITO have been conducted; − however, for the outstanding electrical and optical properties of ITO NPs, studies on optimizing the thickness and annealing process have not been sufficiently performed. It suggests that ITO NPs, which do not require vacuum conditions, can be the starting point for research on cost-effective all-solution electronic devices. , In this work, we studied a cost-effective ITO NP solution-based electrode for high-performance TFHs.…”