Rapid preparation of solution-processed InGaZnO thin films by microwave annealing and photoirradiation

Abstract

We fabricated solution-processed indium–gallium–zinc oxide (IGZO) thin-film transistors (TFTs) by microwave (MW) annealing an IGZO precursor film followed by irradiating with vacuum ultraviolet (VUV) light. MW annealing allows more rapid heating of the precursor film than conventional annealing processes using a hot plate or electric oven and promotes the crystallization of IGZO. VUV irradiation was used to reduce the duration and temperature of the post-annealing step. Consequently, the IGZO TFTs fabricated through MW annealing for 5 min and VUV irradiation for 1 min exhibited an on/off current ratio of 108 and a field-effect mobility of 0.3 cm2 V−1 s−1. These results indicate that MW annealing and photoirradiation is an effective combination for annealing solution processed IGZO precursor films to prepare the semiconductor layers of TFTs.

Inkjet‐Printed and Deep‐UV‐Annealed YAlOx Dielectrics for High‐Performance IGZO Thin‐Film Transistors on Flexible Substrates

“…However, there are still several challenges before the realization of flexible electronics based on printed oxides, and one of them is the requirement of a high‐temperature post deposition annealing (PDA) of the printed layers . To reduce the PDA temperature of the solution‐processed layers, several methods such as deep ultraviolet (DUV) annealing, flash lamp annealing, microwave annealing, and solution combustion synthesis have been proposed for semiconductor, conductor, and dielectric layers. DUV annealing (annealing method in this study) is based on the absorption of the deep UV light (λ < 260 nm) by the precursors used in the solution‐processed deposition resulting in their decomposition into active oxide layers.…”

Solution-Processed Gallium–Tin-Based Oxide Semiconductors for Thin-Film Transistors

“…It is speculated that residual hydroxide groups in the Ga:Sn oxide film are likely to trap charges. Note that the area ratios of O III /O tot of the Sn oxide and Ga:Sn oxide films were 0.41 and 0.51, respectively, and the hydroxide group is known to produce a charge trap state [ 28 ]. Compared to the Ga oxide film, the larger electron concentration of the Ga:Sn oxide film is thought to have originated from a larger concentration of oxygen deficiency, as shown in Figure 2 e. In addition, the Sn oxide film also showed the highest Hall mobility of approximately 1102 cm 2 /Vs; those for the Ga oxide and Ga:Sn oxide films were approximately 201 and 428 cm 2 /Vs, respectively.…”

Printed Electronics Based on Inorganic Semiconductors: From Processes and Materials to Devices

“…Indium–Gallium–Zinc–Oxide : In the first report of amorphous oxide FETs by Hosono and co‐workers (it is the first report where transistor performance and advantages of AOSs have been discussed, otherwise amorphization of oxide semiconductors was known before), a‐IGZO has been prepared by pulsed laser deposition and a transistor mobility of 6–9 cm 2 V −1 s −1 has been reported . With the realization of potential amorphous oxide semiconductors, many researchers soon tried to prepare amorphous oxides, especially a‐IGZO, using solution‐processing techniques . However, in the beginning, the success has rather been limited.…”

“…Here, the process temperature influences the device performance, however, not as significantly as it is the case in conventional methods. Of course, many researchers have utilized photonic curing to reduce process temperatures . One of the early and significant reports involves use of mercury‐based deep UV lamp (major peak is at 253.7 nm) to obtain very high energy photons (180–201 J cm −2 ) to drive the hydrolysis and condensation reactions of metal alkoxides to form MOM bonds; the fabrication of FETs on both rigid (glass) and flexible substrates (polyarylate) have been demonstrated.…”