Ultra-dry air plasma treatment for enhancing the dielectric properties of Al2O3-GPTMS-PMMA hybrid dielectric gate layers in a-IGZO TFT applications.

We assessed the effects of ultra dry-air plasma surface treatments on the properties of Al2O3-GPTMS-PMMA hybrid dielectric layers for applications to high-performance amorphous Indium Gallium Zinc Oxide (a-IGZO) thin film transistors (TFTs). The hybrid layers were deposited by an easy dip coating sol-gel process at low temperature and then treated with dry-air plasma at 1, 2 and 3 consecutive cycles. Their properties were analyzed as a function of the number of plasma cycles and contrasted with those of the untreated ones. The dielectric characteristics of the hybrid layers were determined from I-V and C-f measurements performed on metal-insulator-metal and metal-insulator-semiconductor devices. The results show that the plasma treatments increase the surface energy and wettability of the hybrid films. There is also a reduction of the OH groups and oxygen vacancies in the hybrid network improving the dielectric properties. The incorporation of nitrogen into the hybrid films surface is also observed. The plasma-treated hybrid dielectric layers were applied as dielectric gate in the fabrication of a-IGZO TFTs. The best electrical performance of the fabricated TFTs was achieved with the 3 cycles plasma-treated hybrid dielectric gate, showing high mobility, 29.3 cm2 V-1 s-1, low threshold voltage, 2.9 V, high I ON/OFF current ratio, 106, and low subthreshold swing of 0.42 V dec-1.

Biofunctionalized two-dimensional Ti3C2 MXenes for ultrasensitive detection of cancer biomarker.

In this work, ultrathin Ti3C2-MXene nanosheets were synthesized by minimally intensive layer delamination methods, and uniformly functionalized with aminosilane (f-Ti3C2-MXene) to provide a covalent binding for the immobilized bio-receptor (anti-CEA) for label free, ultrasensitive detection of cancer biomarker (carcinoembryonic antigen, CEA). The effect of different redox probes on the electrochemical behavior of f-Ti3C2-MXene was investigated and found that hexaammineruthenium ([Ru(NH3)6]3+) is the preferable redox probe for biosensing. The fabricated biofunctionalized Ti3C2-MXene exhibits a linear detection range of 0.0001-2000 ng mL-1 with sensitivity of 37.9 µA ng-1 mL cm-2 per decade. The wider linear detection range of our f-Ti3C2-MXene is not only higher than previously reported pristine 2D nanomaterials, but is even comparable to other hybrid 2D nanomaterials. We believe that this work opens a new window for development of MXene-based highly sensitive DNA, aptamer, enzyme, antibody, and cell based biosensors, and could be further used in drug delivery application.

Study of the morphology of ZnS thin films deposited on different substrates via chemical bath deposition.

In this work, the influence of substrate on the morphology of ZnS thin films by chemical bath deposition is studied. The materials used were zinc acetate, tri-sodium citrate, thiourea, and ammonium hydroxide/ammonium chloride solution. The growth of ZnS thin films on different substrates showed a large variation on the surface, presenting a poor growth on SiO2 and HfO2 substrates. The thin films on ITO substrate presented a uniform and compact growth without pinholes. The optical properties showed a transmittance of about 85% in the visible range of 300-800 nm with band gap of 3.7 eV.

Thin film transistors for flexible electronics: contacts, dielectrics and semiconductors.

The development of low temperature, thin film transistor processes that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, radiation detectors, etc. In this paper, we review the impact of gate dielectrics, contacts and semiconductor materials on thin film transistors for flexible electronics applications. We present our recent results to fully integrate hybrid complementary metal oxide semiconductors comprising inorganic and organic-based materials. In particular, we demonstrate novel gate dielectric stacks and semiconducting materials. The impact of source and drain contacts on device performance is also discussed.