Release or transection of superficial medial collateral ligament during open-wedge high tibial osteotomy demonstrated similar clinical outcomes and valgus laxity.

PURPOSE: To analyse whether valgus laxity and clinical outcomes differ depending on whether the superficial medial collateral ligament (sMCL) is released or transected during medial open-wedge high tibial osteotomy (MOWHTO). METHODS: Consecutive patients who underwent MOWHTO and subsequent radiological follow-up for at least 2 years were retrospectively evaluated. The patients were divided into release and transection groups, according to the sMCL manipulation technique. Each patient was assessed for the following variables on valgus stress radiographs taken before surgery and at the 12- and 24-month follow-ups: the absolute value of valgus (ABV) and side-to-side difference (SSD) between the affected and normal sides. The differences between preoperative SSD and those at 12 and 24 months were respectively calculated and defined as delta SSD (ΔSSD). The Visual Analogue Scale, Lysholm knee, International Knee Documentation Committee subjective, and Knee Injury and Osteoarthritis Outcome scores were used to evaluate patient-reported outcomes. RESULTS: Eighty-five patients were included in the study. Forty-two patients (49.6%) underwent sMCL release, and the remaining 43 patients (50.4%) underwent sMCL transection. No significant differences were observed in the ABV and SSD of valgus laxity at the different time points between the two groups (n.s.). Furthermore, no significant differences were observed in the ΔSSD at the 12- and 24-month follow-ups between the two groups (n.s.). Significant improvement from preoperative values was observed in all patient-reported outcomes (p < 0.001), with no significant differences between the two groups at any time point (n.s.). CONCLUSION: Significant improvements in clinical outcomes were observed, regardless of the technique used. Postoperative valgus laxity did not occur with either technique. The transection technique, which can be performed more simply and quickly, demonstrated similar clinical outcomes and valgus laxity to the release technique. LEVEL OF EVIDENCE: Level III.

Significance of Pairing In/Ga Precursor Structures on PEALD InGaOx Thin-Film Transistor.

Atomic layer deposition (ALD) is a promising deposition method to precisely control the thickness and metal composition of oxide semiconductors, making them attractive materials for use in thin-film transistors because of their high mobility and stability. However, multicomponent deposition using ALD is difficult to control without understanding the growth mechanisms of the precursors and reactants. Thus, the adsorption and surface reactivity of various precursors must be investigated. In this study, InGaO (IGO) semiconductors were deposited by plasma-enhanced atomic layer deposition (PEALD) using two sets of In and Ga precursors. The first set of precursors consisted of In(CH3)3[CH3OCH2CH2NHtBu] (TMION) and Ga(CH3)3[CH3OCH2CH2NHtBu]) (TMGON), denoted as TM-IGO; the other set of precursors was (CH3)2In(CH2)3N(CH3)2 (DADI) and (CH3)3Ga (TMGa), denoted as DT-IGO. We varied the number of InO subcycles between 3 and 19 to control the chemical composition of the ALD-processed films. The indium compositions of TM-IGO and DT-IGO thin films increased as the InO subcycles increased. However, the indium/gallium metal ratios of TM-IGO and DT-IGO were quite different, despite having the same InO subcycles. The steric hindrance of the precursors and different densities of the adsorption sites contributed to the different TM-IGO and DT-IGO metal ratios. The electrical properties of the precursors, such as Hall characteristics and device parameters of the thin-film transistors, were also different, even though the same deposition process was used. These differences might have resulted from the growth behavior, anion/cation ratios, and binding states of the IGO thin films.

Organic/Inorganic Hybrid Buffer in InGaZnO Transistors under Repetitive Bending Stress for High Electrical and Mechanical Stability.

We investigated the influence of the multilayered hybrid buffer consisting of Al2O3/PA (polyacrylic) organic layer/Al2O3 on the electrical and mechanical properties of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs). The multilayered organic/inorganic hybrid buffer has multiple beneficial effects on the flexible TFTs under repetitive bending stress. First, compared to the PA or Al2O3 single-layered buffer, the multilayered hybrid buffer showed an improved WVTR value of 1.1 × 10-4 g/m2 day. Even after 40,000 bending cycles, the WVTR value of the hybrid buffer increased only by 17%, while the WVTR value of the Al2O3 layer doubled after cyclical bending stress. We also confirmed that the hybrid buffer has advantages in mechanical durability of the TFT layers because of the change in the position of the neutral plane and the strain reduction effect by the PA organic layer. When we fabricate a top-gate a-IGZO TFT with the hybrid buffer layer (HB TFT), the device shows Vth = 0.74 V, µFE = 14.4 cm2/V·s, a subthreshold slope of 0.27 V/dec, and hysteresis of 0.21 V, which are superior to that of TFTs fabricated on an Al2O3 single-layer buffer (IB TFT). From the X-ray photoelectron spectroscopy and elastic recoil detection analysis, the difference in the electrical performance of TFTs could be explained by hydrogen-related molecules. After annealing at 270 °C, the amounts of hydrogen found in the a-IGZO layer for the IB, HB, and OB TFTs were 3.57 × 1021, 5.77 × 1021, and 7.34 × 1021 atoms/cm3, respectively. A top-gate bottom-contact structured a-IGZO TFT fabricated on the PA layer (OB TFT) showed a gate dielectric breakdown because of excessively high hydrogen content and high nonbonding oxygen content. On the other hand, HB TFTs showed better positive bias stability because of the higher hydrogen concentration, as hydrogen (when not excessive) is beneficial in passivating electron traps. Finally, we conducted 60,000 repetitive bending cycles on IB TFTs and HB TFTs with various bending radii down to 1.5 mm. The HB TFT shows improved mechanical durability and exhibits less electrical degradation during and after repetitive bending stress, compared to the IB TFT.

Ultra-High-Speed Intense Pulsed-Light Irradiation Technique for High-Performance Zinc Oxynitride Thin-Film Transistors.

In this study, we investigated the effects of intense pulsed light (IPL) on the electrical performance properties of zinc oxynitride (ZnON) thin films and thin-film transistors (TFTs) with different irradiation energies. Using the IPL process on the oxide/oxynitride semiconductors has various advantages, such as an ultrashort process time (∼100 ms) and high electrical performance without any additional thermal processes. As the irradiation energy of IPL increased from 30 to 50 J/cm2, the carrier concentration of ZnON thin films decreased from 5.07 × 1019 to 9.96 × 1016 cm-3 and the electrical performance of TFTs changed significantly, which is optimized at an energy of 40 J/cm2 (field effect mobility of 48.4 cm2 V-1 s-1). The properties of TFTs, such as mobility, subthreshold swing, and hysteresis, and the stability of the device under negative bias degraded as the irradiation energy increased. This degradation contributed to the change in nitrogen-related bonding states, such as nonstoichiometric Zn xN y and N-N bonding, rather than that of oxygen-related bonding states and the atomic composition of ZnON thin films. Optimization of the IPL process in our results makes it possible to produce high-performance ZnON TFTs very fast without any additional thermal treatment, which indicates that highly productive TFT fabrication can be achieved via this process.

Near-Infrared Photoresponsivity of ZnON Thin-Film Transistor with Energy Band-Tunable Semiconductor.

Amorphous oxide semiconductors have attracted attention in electronic device applications because of their high electrical uniformity over large areas, high mobility, and low-temperature process. However, photonic applications of oxide semiconductors are highly limited because of their larger band gap (over 3.0 eV). Here, we propose low band gap zinc oxynitride semiconductors not only because of their high electrical performance but also their high photoresponsivity in the vis-NIR regions. The optical band gap of zinc oxynitride films, which is in the range of 0.95-1.24 eV, could be controlled easily by changing oxygen and nitrogen ratios during reactive sputtering. Band gap tuned zinc oxynitride-based phototransistors showed significantly different photoresponse following both threshold voltage and drain current changes due to variation in nitrogen-related defect sites.

Photothermally Activated Nanocrystalline Oxynitride with Superior Performance in Flexible Field-Effect Transistors.

Photochemical reactions in inorganic films, which can be promoted by the addition of thermal energy, enable significant changes in the properties of films. Metaphase films depend significantly on introducing external energy, even at low temperatures. We performed thermal-induced, deep ultraviolet-based, thermal-photochemical activation of metaphase ZnOxNy films at low temperature, and we observed peculiar variations in the nanostructures with phase transformation and densification. The separated Zn3N2 and ZnO nanocrystalline lattice in amorphous ZnOxNy was stabilized remarkably by the reduction of oxygen defects and by the interfacial atomic rearrangement without breaking the N-bonding. On the basis of these approaches, we successfully demonstrated highly flexible, nanocrystalline-ZnOxNy thin-film transistors on polyethylene naphthalate films, and the saturation mobility showed more than 60 cm2 V-1 s-1.

The resonant interaction between anions or vacancies in ZnON semiconductors and their effects on thin film device properties.

Zinc oxynitride (ZnON) semiconductors are suitable for high performance thin-film transistors (TFTs) with excellent device stability under negative bias illumination stress (NBIS). The present work provides a first approach on the optimization of electrical performance and stability of the TFTs via studying the resonant interaction between anions or vacancies in ZnON. It is found that the incorporation of nitrogen increases the concentration of nitrogen vacancies (VN+s), which generate larger concentrations of free electrons with increased mobility. However, a critical amount of nitrogen exists, above which electrically inactive divacancy (VN-VN)0 forms, thus reducing the number of carriers and their mobility. The presence of nitrogen anions also reduces the relative content of oxygen anions, therefore diminishing the probability of forming O-O dimers (peroxides). The latter is well known to accelerate device degradation under NBIS. Calculations indicate that a balance between device performance and NBIS stability may be achieved by optimizing the nitrogen to oxygen anion ratio. Experimental results confirm that the degradation of the TFTs with respect to NBIS becomes less severe as the nitrogen content in the film increases, while the device performance reaches an intermediate peak, with field effect mobility exceeding 50 cm2/Vs.

High-Performance Zinc Tin Oxide Semiconductor Grown by Atmospheric-Pressure Mist-CVD and the Associated Thin-Film Transistor Properties.

Zinc tin oxide (Zn-Sn-O, or ZTO) semiconductor layers were synthesized based on solution processes, of which one type involves the conventional spin coating method and the other is grown by mist chemical vapor deposition (mist-CVD). Liquid precursor solutions are used in each case, with tin chloride and zinc chloride (1:1) as solutes in solvent mixtures of acetone and deionized water. Mist-CVD ZTO films are mostly polycrystalline, while those synthesized by spin-coating are amorphous. Thin-film transistors based on mist-CVD ZTO active layers exhibit excellent electron transport properties with a saturation mobility of 14.6 cm2/(V s), which is superior to that of their spin-coated counterparts (6.88 cm2/(V s)). X-ray photoelectron spectroscopy (XPS) analyses suggest that the mist-CVD ZTO films contain relatively small amounts of oxygen vacancies and, hence, lower free-carrier concentrations. The enhanced electron mobility of mist-CVD ZTO is therefore anticipated to be associated with the electronic band structure, which is examined by X-ray absorption near-edge structure (XANES) analyses, rather than the density of electron carriers.