Dinkar S. Patil

An efficient fast response and high-gain solar-blind flexible ultraviolet photodetector employing hybrid geometry

We report high performance flexible hybrid ultraviolet photodetector with solar-blind sensitivity using nanocomposite film of plasma polymerized aniline-titanium dioxide. A facile solvent-free plasma technique is used to synthesize superior quality hybrid material with high yield. The hybrid photodetector exhibited high photoconductive gain of the order of ∼105 and fast speed with response and recovery time of 22.87 ms and 34.23 ms. This is an excellent result towards getting a balance in the response speed and photoconductive gain trade-off of the photodetectors reported so far. In addition, the device has the advantages of enhanced photosensitivity ((Ilight − Idark)/Idark) of the order of ∼102 and high responsivity of ∼104 AW−1. All the merits substantiates that, to prepare hybrid material, plasma based method holds potential to be an easy way for realizing large scale nanostructured photodetectors for practical applications.

Synthesis of Sterically Hindered 1,3‐Diketones

Abstract An efficient and practical method for the synthesis of sterically hindered aliphatic/aromatic 1,3‐diketones via coupling of ketones with esters using potassium tert‐butoxide is described. The protocol requires milder operating conditions, and the products are obained in good to excellent yields.

Microwave electron cyclotron resonance plasma metal organic chemical vapour deposition of Y2O3 coatings

Y2O3 thin films were deposited on Si (111) and s.s. substrates by microwave electron cyclotron resonance (ECR) plasma metal organic chemical vapour deposition (MOCVD) using a Y(thd)3 (thd = 2,2,6,6,-tetramethyl-3,5-heptanedionate) precursor at a substrate temperature of 450 C. The deposited coatings were characterized by x-ray photoelectron spectroscopy (XPS). From the observed binding energies of the photoelectrons Y 3d5/2, Y 3d3/2 and O 1s, deposition of Y2O3 coating on the substrates is confirmed. Along with Y2O3 some carbon deposition is also seen. Oxygen plasma annealing of the deposited coatings with increase in the substrate temperature shows reduction in the carbon content in the coating. Details regarding deposition experiments, effects of oxygen plasma annealing and characterization of coatings are discussed in this paper.

Hydroarylation of arenes with styrenes using Montmorillonite K-10 as an efficient, selective, and recyclable catalyst

Abstract Hydroarylation of styrene and its derivatives with arenes and heteroarenes was studied using Montmorillonite K-10 as an efficient, environmentally benign, economical, greener, and recyclable catalyst. The reaction gives 1,1-diarylalkanes with a very high selectivity and excellent yields in short time with greater substrate compatibility.

Bias-independent growth of carbon nanowalls by microwave electron-cyclotron resonance plasma CVD

The investigations reported here describe the synthesis of carbon nanowalls (CNWs) by microwave electron-cyclotron resonance (ECR) plasma-assisted chemical vapour deposition (PACVD) process without an application of external bias to the substrate during growth. CNWs were grown on silicon (Si) substrates using hydrogen (H2)/methane (CH4) plasma at 650°C substrate temperature. Nickel (Ni) was used as a catalyst for the synthesis of CNWs. To the best of our knowledge, this is the first report that describes the bias-independent growth of CNWs using the ECR PACVD process. Formation of CNWs is confirmed by scanning electron microscopy and Raman spectroscopy. The discussion part also includes a possible growth mechanism for CNWs in terms of the role of surface plasmons.

Plasma sprayed hydroxy apatite coatings

This paper describes the method of producing plasma sprayed coatings of hydroxy apatite (HA) on metallic substrates of Ti-6Al-4V. Hydroxy apatite is a material which has similar composition to that of the mineral phase of the human bone. Poor mechanical properties however inhibits its use in the load bearing applications. The powders prepared in our laboratory are sprayed using a plasma spray torch operating in ambient. The deposited coatings are charaterized by X-ray diffraction and found to retain HA in the coatings as per requirements.

A possible explanation of the anomalous emissive probe behavior in a reactive RF plasma

Emissive probe diagnostics in saturated floating potential mode was carried out in RF plasmas of argon (Ar)–methane (CH4) and Ar–CH4–hexa methyl disiloxane (HMDSO). These plasmas are used for the deposition of diamond-like carbon (DLC) and SiOx-containing DLC films, respectively. While performing the experiments it was found that the probe characteristics had two saturation regions instead of one. The same measurements when repeated in Ar and Ar–N2 plasmas showed a single saturation as expected. The first experiments when repeated again showed the same anomaly. The experimental findings question the validity of emissive probe diagnostics in reactive plasmas. A possible model of dust formation inside the reactive plasma is predicted and the first saturation is linked to dust. The second saturation is credited as the actual plasma potential. The concept of dust was invoked after being sure that no effects of RF and reference electrode contamination are responsible for this behavior. The results indicate that we should remain cautious when using emissive probes in reactive plasmas as they may occasionally lead to erroneous results.

Cold Plasma Processing of Materials for Extreme Conditions

Abstract This chapter discuses cold plasma-based processing of materials that are required for extreme conditions. Starting with the introduction regarding types of plasma that are being used for cold plasma-based processing of materials, the main focus of this chapter will be discussion of low-pressure plasmas for surface modification by plasma-assisted chemical vapor deposition (CVD). The role of low-pressure plasmas in CVD applications is covered. A discussion also covers plasma sources (direct current, radio frequency, microwave, and microwave electron cyclotron resonance) that are used for low-pressure plasma CVD applications. A few selected examples will be discussed regarding how low-pressure plasma CVD is used for deposition of diamond and diamondlike carbon coatings, yttria and yttria-stabilized zirconia-based coatings using metal organic precursors and SiO x -based plasma polymerized corrosion resistant coatings. The chapter discusses processing and characterization aspects of deposited coatings.