Characteristics of Oxide TFT Using Carbon-Doped Ιn₂O₃ Thin Film Fabricated by Low-Temperature ALD Using Ethylcyclopentadienyl Indium (Ιn-EtCp) and H₂O & O₃

Abstract

We investigated characteristic of the In2O3 films deposited by various atomic layer deposition (ALD) conditions such as growth temperature and doses of InEtCp precursor and H2O/O3 oxidant gases. A self-limited ALD window was observed in the In2O3 film deposition when an InEtCp and H2O/O3 doses were supplied over 27.6 µmol and 0.09/2.94 mmol, respectively, regardless of the growth temperature. The ratio of In:O:C of the In2O3 films at 150, 170 and 200 ºC were 1:1.16:0.04 (InO1.16C0.04), 1:1.16:0.03 (InO1.16C0.03) and 1:1.2:0 (InO1.2), respectively. We found that the carbon-doped (InO1.16C0.04, InO1.16C0.03) and carbon-free In2O3 (InO1.2) films could be easily deposited by changing the growth temperature. All films had an amorphous structure. The electrical properties of InO1.16C0.04 TFT changed dramatically from metal-like conductor to semiconductor after post-metallization annealing at 150 ºC in O3 while no InO1.2 TFT changed. This is thought to be due to the suppression of excess oxygen vacancies in InO1.16C0.04 channel by effect of doped carbon. The InO1.16C0.04 TFT exhibited superior characteristics of S.S (0.37 V/dec), I on/I off (1.0×108), V th (3.5 V) and saturation field effect mobility (20.4 cm2/Vs). Therefore, carbon-doped Ιn2O3 is a promising material as a channel of a flexible TFT where low temperature formation is essential.

Atomic layer deposition for nanoscale oxide semiconductor thin film transistors: review and outlook

“…This sequential process of the reactant pair (WO) resulted in a highly developed GPC. A similar result was observed by Kobayashi et al using In-EtCp as a precursor [117]. The different roles of the two oxidants led to improved results, in that H 2 O releases ligands or byproducts from the surface and O 2 oxidizes the indium.…”

Structural, Optical, and Electrical Properties of InOx Thin Films Deposited by Plasma-Enhanced Atomic Layer Deposition for Flexible Device Applications

“…These previous studies reported that InO x generally formed a clear polycrystalline cubic structure with a preferred orientation of (211), (222), or (400), depending on the deposition method and process conditions. − Among them, ALD has emerged as a promising deposition technique due to its low-temperature process, good uniformity, excellent step coverage, and controllability of material properties, such as the binding state and crystallinity . In addition, some previous studies have reported that the preferable electrical performance of ALD-processed InO x devices is comparable with those synthesized by a solution and sputtering because of the higher film density induced by a self-limited reaction on the growth surface. ,, For these reasons, the ALD-processed InO x film may be a promising active channel layer for the backplane of next-generation displays. ,, Yeom et al demonstrate the device with the high mobility of 39 cm 2 /V s using the Et 2 InN­(SiMe 3 ) 2 precursor, and Lee et al also present the InO x TFT device using the ([3-(dimethylamino)­propyl]­dimethyl indium) (DADI) precursor. However, high growth or annealing temperatures are required for practical device characteristics, suggesting that it is still challenging to apply to flexible substrates.…”

“…17 In addition, some previous studies have reported that the preferable electrical performance of ALD-processed InO x devices is comparable with those synthesized by a solution and sputtering because of the higher film density induced by a self-limited reaction on the growth surface. 3,18,19 For these reasons, the ALD-processed InO x film may be a promising active channel layer for the backplane of next-generation displays. 8,20,21 Yeom et al 8 demonstrate the device with the high mobility of 39 cm 2 /V s using the Et 2 InN(SiMe 3 ) 2 precursor, and Lee et al 21 also present the InO x TFT device using the ([3-(dimethylamino)propyl]dimethyl indium) (DADI) precursor.…”

Influence of adsorbed oxygen concentration on characteristics of carbon-doped indium oxide thin-film transistors under bias stress

“…24) In 2 O 3 -based metal oxide films have been deposited using various deposition methods such as radio-frequency magnetron sputtering, 25) sol-gel processing, 26) solution processing, 27,28) inkjet printing, 29) chemical vapor deposition (CVD), 30) and atomic layer deposition (ALD). [31][32][33][34][35][36][37][38][39][40][41] In 2 O 3 films deposited via sputtering at room temperature typically have a polycrystalline structure. Moreover, as-grown In 2 O 3 films deposited using solgel, inkjet printing, and CVD methods sometimes contain residual impurities from the precursors; a high-temperature annealing process must then be carried out to reduce these residual impurities.…”