The electronic structure of co-sputtered zinc indium tin oxide thin films

Abstract

Spin polarization and charge transmission for a waveguide on surface of topological insulator Appl. Phys. Lett. 99, 153104 (2011) Behavior of nitrogen atoms in SiC-SiO2 interfaces studied by electrically detected magnetic resonance Appl. Phys. Lett. 99, 142105 (2011) Influence of deep levels on capacitance-voltage characteristics of AlGaN/GaN heterostructures J. Appl. Phys. 110, 073702 (2011) Electronic states at the interface between indium tin oxide and silicon J. Appl. Phys. 110, 074503 (2011) Improved calculation of vacancy properties in Ge using the Heyd-Scuseria-Ernzerhof range-separated hybrid functional J. Appl. Phys. 110, 063534 (2011) Additional information on J. Appl. Phys. Zinc indium tin oxide (ZITO) transparent conductive oxide layers were deposited via radio frequency (RF) magnetron co-sputtering at room temperature. A series of samples with gradually varying zinc content was investigated. The samples were characterized with x-ray and ultraviolet photoemission spectroscopy (XPS, UPS) to determine the electronic structure of the surface. Valence and conduction bands maxima (VBM, CBM), and work function were determined. The experiments indicate that increasing Zn content results in films with a higher defect rate at the surface leading to the formation of a degenerately doped surface layer if the Zn content surpasses $50%. Furthermore, the experiments demonstrate that ZITO is susceptible to ultraviolet light induced work function reduction, similar to what was earlier observed on ITO and TiO 2 films.

Compositional influence on the electrical performance of zinc indium tin oxide transparent thin-film transistors

“…This result is an agreement with the reported by Ryu et al [9] The decrease of the mobility values is in good agreement with a supposed rise of oxygen vacancies with an increasing Zn content ratio [2,5]: a higher oxygen vacancy density enhances the coulomb scattering of free electrons by the ionized defects, thus causing the degradation of the mobility [19]. Remarkably enough, this huge drop in mobility may not only be attributed to oxygen vacancies but also to non-idealities, such as series resistance, in the contact-semiconductor interface.…”

“…According to reference [5], the oxygen vacancy density is much higher at the surface than in the bulk. When the TFT channel is depleted (i.e.…”

“…All the TFTs with ZITO active channel studied herein have been fabricated using a bottom gate-top contact structure as depicted in figure 1 Increasing the Zn content increases the O vacancy density at the film surface, as it has been reported by Carreras et al [5,12], thus resulting in a highly conductive surface layer [13]. To reduce this effect, one sample of each kind was annealed in air atmosphere.…”

“…The electrical, optical and morphological properties of this alloy have been previously characterized [3,4]. Moreover, its electronic band structure has been also carefully studied [5]. The aim of this work is to study the electronic properties of different ZITO layers by manufacturing thin film transistors (TFTs) [6 -10].…”

“…As the Zn concentration increases, the O vacancies at the layer surface are said to increase [2,5], thus indicating a higher density of charge carriers (electrons in this case). An annealing process in air atmosphere has been applied to each layer in order to reduce the carrier concentration by decreasing the number of O vacancies.…”