Growth of Transparent nc-InGaO[sub 3](ZnO)[sub 2] Thin Films with Indium mol Ratios Using Solution Process

Abstract

The effect of indium mol ratio on nanocrystalline ͑nc͒-InGaO 3 ͑ZnO͒ 2 thin films prepared by solution was investigated with structural properties. The size of nanocrystallines tended to increase up to 120 nm with an optimized indium mol ratio after second postannealing at 700°C for 10 s with three cycles. The shape of the nanocrystallines and their growth were determined by the indium mol ratio. The main ͑008͒ growth direction, which had a columnar structure, could be retarded by a high indium mol ratio, which could generate the ͑100͒ direction growth. After postannealing, the films had with less oxygen deficiency and main stoichometric oxygen bound with metal ͑In, Ga, and Zn͒. The growth of nanocrystallines during the second postannealing from small grains with random orientation to large grains with well-aligned orientation could be explained by a self-solid phase reaction with decomposition and combination of precursor without any additional epitaxial layer. It implied that the crystallinity of nc-InGaO 3 ͑ZnO͒ 2 thin films was strongly dependent on process parameters such as temperature and component mol ratio.High performance oxide semiconductor thin films have been the significant attention for the large area device application of the information display, solar cells, and sensor, due to electrical and optical properties. 1 Usually, most oxide semiconductors need a high deposition temperature and postannealing treatment in ambient air or oxygen to improve their electrical and optical properties. 2-4 For example, ZnO thin films are typically deposited at comparatively low temperature and postannealed at high temperatures to relax the intrinsic defects and stress. 5 The indium doped ZnO thin films deposited at relatively high temperatures are used to fabricate high quality films. 5 Control of the size, shape, and crystal structure of nanocrystal oxide materials is an important parameter for improving performance of the thin films due to their unique size-and shapedependent characteristics. 6,7 The optical and electrical properties of InGaZnO thin films with different gallium/indium ratio deposited by the sputtering method has been reported. 8 With increasing indium content and a fixed gallium content, there is no significant difference in the refractive index in the transparent range, whereas the refractive index is clearly reduced in the opaque range. Further, the turn-on voltage of InGaZnO thin film transistor increases with increasing gallium/indium ratio. 8 Also, the mobility is largely influenced by the indium composition and carrier concentration is controlled by the amount of gallium. 1 However, the effect of the indium component on structure properties has rarely been investigated for the growth of In-Ga-Zn oxide semiconductors.In this paper, we fabricate nc-InGaO 3 ͑ZnO͒ 2 thin films using a sol-gel process with two-step postannealing to improve crystallinity. The effects of different indium mol ratios on structural properties, including the lattice mismatch, the shape of nanocrystallines, and self-s...

Controllable crystallinity of synthesized In–Ga–Zn–O nano‐powder by using a pulp precursor for printing processes

“…The relative intensity of the diffraction peak increased with increasing indium composition, indicating that the crystallinity of the IGZO nanoparticles depended on the indium content. Recently, Kim et al reported that an increase in the indium composition ratio in the solution‐processed nanocrystalline films leads to a decrease in grain size and a loss of crystallinity because the addition of indium obstructs c‐axis growth and cause the lattice strain 21, 22. However, the results in the present study were not in agreement with the results reported by Kim.…”

“…However, the results in the present study were not in agreement with the results reported by Kim. et al This might be due to the difference in growth method, which involved a pulp precursor and the addition of a solution such as 2‐methoxyethanol and monoethanolamine 21, 22. A further investigation of this effect is currently underway.…”

High performance solution-deposited amorphous indium gallium zinc oxide thin film transistors by oxygen plasma treatment

“…3,4 In comparison to the vacuum deposition techniques, the use of solution process techniques offers an inexpensive fabrication of active matrix backplanes for large-area display applications. Solution based deposition methods such as spin coating, [5][6][7][8][9] ink-jet, 10,11 and gravure printing 12 have been used in the past few years for the fabrication of a-IGZO TFTs. However, high processing temperature and low device performance restrict the solution-derived a-IGZO TFTs to be used for low cost and high performance electronic applications.…”

Investigation on Atomic Bonding Structure of Solution-Processed Indium-Zinc-Oxide Semiconductors According to Doped Indium Content and Its Effects on the Transistor Performance

“…Moreover, studies on process developments such as atomic composition ratio, doping, and chemical treatment have remarkably improved TFT performance [ 12 , 13 ]. Among them, in the studies focusing on the atomic composition ratio, the field-effect mobilities in the range 0.5–10.0 cm·V −1 s −1 were controlled by varying the ratio of In:Zn or In:Zn:Ga, and the thickness, roughness, and crystallinity of the semiconductor film were investigated relative to the atomic ratio [ 14 , 15 , 16 ]. Furthermore, a field-effect mobility of over 10 cm·V −1 s −1 was demonstrated using various dopant materials [ 17 , 18 , 19 , 20 ], and a mobility improvement of approximately ten times was achieved by applying chemical treatment or post-treatment [ 21 , 22 ].…”