Water-Processed Ultrathin Crystalline Indium–Boron–Oxide Channel for High-Performance Thin-Film Transistor Applications

Abstract

Thin-film transistors (TFTs) made of solution-processable transparent metal oxide semiconductors show great potential for use in emerging large-scale optoelectronics. However, current solution-processed metal oxide TFTs still suffer from relatively poor device performance, hindering their further advancement. In this work, we create a novel ultrathin crystalline indium–boron–oxide (In-B-O) channel layer for high-performance TFTs. We show that high-quality ultrathin (~10 nm) crystalline In-B-O with an atomically smooth nature (RMS: ~0.15 nm) could be grown from an aqueous solution via facile one-step spin-coating. The impacts of B doping on the physical, chemical and electrical properties of the In2O3 film are systematically investigated. The results show that B has large metal–oxide bond dissociation energy and high Lewis acid strength, which can suppress oxygen vacancy-/hydroxyl-related defects and alleviate dopant-induced carrier scattering, resulting in electrical performance improvement. The optimized In-B-O (10% B) TFTs based on SiO2/Si substrate demonstrate a mobility of ~8 cm2/(V s), an on/off current ratio of ~106 and a subthreshold swing of 0.86 V/dec. Furthermore, by introducing the water-processed high-K ZrO2 dielectric, the fully aqueous solution-grown In-B-O/ZrO2 TFTs exhibit excellent device performance, with a mobility of ~11 cm2/(V s), an on/off current of ~105, a subthreshold swing of 0.19 V/dec, a low operating voltage of 5 V and superior bias stress stability. Our research opens up new avenues for low-cost, large-area green oxide electronic devices with superior performance.

Aqueous Solution-Grown Crystalline Phosphorus Doped Indium Oxide for Thin-Film Transistors Applications

“…The characteristic diffraction peaks of (222) (dominant peak), (400), (440), and (622) are assignable to bixbyite In 2 O 3 (JCPDS 06-0416). No P 2 O 5 or other phases are observed from the diffraction pattern, which means that P addition does not break the In 2 O 3 matrix crystalline structure [ 18 , 19 ]. We suppose that the added P replaces the In sites and maintains the cubic In 2 O 3 structure when the P doping amount is relatively low; however, the diffraction peak intensity gradually decreases, suggesting the reduction of crystallinity after P incorporation [ 20 ].…”

“…By using Tauc equation, the optical bandgaps of IPO films ( Figure 3 b) are calculated to be 3.61 eV (0% P), 3.66 eV (3% P), 3.88 eV (6% P), and 4.19 eV (9% P), respectively. The increased bandgap with P addition could be due to the fact that P can inhibit the formation of oxygen-vacancy defects in In 2 O 3 [ 19 ]. The increased bandgap is more in line with the larger binding strength of P-O (599.1 KJ/mol) than that of In-O bonding (320.1 KJ/mol), indicating the effective oxygen-vacancy-related defects suppression [ 21 ].…”

Electrical performance of La-doped In2O3 thin-film transistors prepared using a solution method for low-voltage driving

“…8 Thus, researchers have proposed many methods to improve the performance of In 2 O 3 TFTs. For example, the performance of TFTs has been improved by selecting suitable dopants as carrier suppressors such as Tb, 9 B, 10 Sr, 11 and Ni. 12 Standard electrode potential (SEP), electronegativity and the ability to bind oxygen are the main criteria for selecting a suitable dopant.…”

“… 8 Thus, researchers have proposed many methods to improve the performance of In 2 O 3 TFTs. For example, the performance of TFTs has been improved by selecting suitable dopants as carrier suppressors such as Tb, 9 B, 10 Sr, 11 and Ni. 12 …”