Zinc–Tin Oxide Film as an Earth-Abundant Material and Its Versatile Applications to Electronic and Energy Materials

Zinc–Tin Oxide (ZTO) films potentially offer desirable properties for next-generation devices and are considered promising candidates due to the following merits: (I) zinc and tin are abundant on Earth, with estimated reserves of approximately 250 million tons and 4.3 billion tons, respectively, (II) zinc and tin are harmless to the human body, and (III) large-area manufacturing with various synthesis processes is available. Considering the advantages and promises of these ZTO films, this review provides a timely overview of the progress and efforts in developing ZTO-based electronic and energy devices. This review revisits the ZTO films used for various device applications, including thin-film transistors, memory devices, solar cells, and sensors, focusing on their strong and weak points. This paper also discusses the opportunities and challenges for using ZTO films in further practical electronic and energy device applications.

High-performance metal-semiconductor-metal ZnSnO UV photodetector via controlling the nanocluster size

Solution processing of amorphous oxide semiconductors (AOS) is used for electronic and optoelectronic applications. However, the device performance is much lower than that for a device that is fabricated using vacuum processing. This study uses acetylacetone (acac) as an additive in the precursor solution to reduce the nanocluster size in a ZnSnO (ZTO) film. A metal-semiconductor-metal (MSM)-type UV photodetector (PD) is fabricated using as-prepared ZTO film. ZTO film that features a smaller nanocluster size, so more oxygen vacancies are induced, which produces more electrons and the photocurrent is increased. The surface at the metal/semiconductor interface is smoother so there is greater contact with fewer interface states and the dark current is decreased. An extremely high photo-to-dark current ratio (PDCR) of 1314 is achieved for a solution-processed ZTO MSM-type PD.

Effect of Oxygen Vacancy Ratio on a GaZTO Solar-Blind Photodetector

A gallium-zinc-tin-oxide (GaZTO) solar-blind photodetector was fabricated via radio frequency sputtering. The transmittance of the GaZTO thin film was >80% in the visible light region, and its energy bandgap ranged from 4.11 to 4.23 eV. Manipulating the oxygen flows changed the ratio of oxygen vacancies, which was confirmed by X-ray photoelectron spectroscopy. The ratio of oxygen vacancies in the GaZTO thin films impacted the performance of the photodetectors. The photocurrent, responsivity, and ultraviolet–visible rejection ratio of the GaZTO solar-blind photodetector were 1.23 × 10−6 A, 9.12 × 10−2 A/W, and 3.48 × 104, respectively, at a 10 V bias under 280 nm light illumination. The transient responses of the synthesized photodetectors were measured and discussed.

Dual role of Ag nanowires in ZnO quantum dot/Ag nanowire hybrid channel photo thin film transistors

High mobility and p-type thin film transistors (TFTs) are in urgent need for high-speed electronic devices. In this work, ZnO quantum dot (QD)/Ag nanowire (NW) channel TFTs were fabricated by a solution processed method. The Ag NWs play the dual role of dopant and providing the charge transfer route, which make the channel p-type and enhance its mobility, respectively. The best sample yields an on/off ratio (I on/I off) of 5.04 × 105, a threshold voltage (V T) of 0.73 V, a high field effect mobility (μ FE) of 8.69 cm2 V-1 s-1, and a subthreshold swing (SS) of 0.41 V dec-1. Owing to the strong ultraviolet (UV) absorption and photo-induced carrier separation ability of ZnO QDs and the fast carrier transport of Ag NWs, the devices acquire a high external quantum efficiency (EQE) and ultra-fast response under 365 nm UV illumination. The UV-modulated ZnO QD/Ag NW hybrid channel photo TFTs have potential for future application in optoelectronic devices, such as photodetectors and photoswitches.