nan Ishpal

Effect of high substrate bias and hydrogen and nitrogen incorporation on density of states and field-emission threshold in tetrahedral amorphous carbon films

This article reports the influence of substrate bias during growth and of hydrogen and nitrogen incorporation on density of states [N (EF)] and field-emission threshold (Eturn-on) in tetrahedral amorphous carbon (ta-C) films, deposited using an S-bend filtered cathodic vacuum arc process. The variation in negative substrate bias from −20 to −200 V was found to initially lead to a small decrease in N (EF) and Eturn-on, and a small increase in the emission current density (J) at 12.5u2002V/μm in the case of as-grown ta-C films; beyond −200 V substrate bias there is a reversal in the trend. The values of N (EF)=1.3×1017u2002cm−3u2009eV−1, Eturn-on=8.3u2002V/μm, and J=6.19u2002mA/cm2 were observed at −200 V substrate bias. However at −300 V the properties were not very different from those at −200 V substrate bias and so with a view to use the higher energy, hydrogen and nitrogen incorporation studies were carried out in this condition. It was observed that there was further enhancement in properties with hydrogen and nitrogen i...

Investigation of radio frequency plasma for the growth of diamond like carbon films

The radio frequency has been used to generate plasma of argon, acetylene gases, and their mixture should be replaced by mixture in a plasma enhanced chemical vapor deposition system. The generated plasma discharge has been characterized by an impedance analyzer (VI probe) for the evaluation of various electrical parameters of the plasma discharge such as rf-voltage, rf-current, phase, impedance, and actual power consumed by the plasma discharge. These plasma parameters have been analyzed as a function of self-bias, which are found to depend on applied power, pressure, and reactor geometry of the system. Subsequently, same plasma conditions were used for the deposition of diamond like carbon (DLC) films. The argon plasma has lowest impedance (16.02 Ω) value and highest average electron density (2.77u2009×u20091010u2009cm−3) value at −150 V self-bias. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy measurements have been performed on the prepared DLC films for the evaluation of the chemical bonding. XPS s...

Structural, Nanomechanical, and Field Emission Properties of Amorphous Carbon Films Having Embedded Nanocrystallites Deposited by Filtered Anodic Jet Carbon Arc Technique

This paper reports the effect of substrate bias on the structural, nanomechanical, and field emission properties of amorphous carbon films having embedded nanocrystallites (a-C:nc films) deposited by filtered anodic jet carbon arc technique. X-ray diffraction results exhibit predominantly an amorphous nature of the films. High-resolution transmission electron microscope images showed the amorphous nature of the films with nanocrystallites embedded in the amorphous matrix. Ultrafine nanograined microstructures with average grain size between 20 and 30u2009nm are observed throughout the film with a majority of the grains of single crystallites. A strong influence of substrate bias has been observed on the structural, nanomechanical, and field emission properties. Maximum nanohardness (H) of 58.3u2009GPa, elastic modulus (E) of 426.2u2009GPa, and H/E of 0.136 have been observed in a-C:nc films deposited at −60u2009V substrate bias which showed 82.6% sp3 content.