P. N. Dixit

Diamond‐like carbon films grown using a saddle field source

This article reports the measurement of deposition rate, dark conductivity versus temperature, optical band gap, refractive index, extinction coefficient, hardness, adhesion, and internal stress of diamond‐like carbon (DLC) films grown by aspirating hydrocarbon gases (CH4 and C2H2) and C6H6 vapors into a saddle field source. The source operates at 0.7–1.0 kV in the pressure range of 1.0×10−4–7.0×10−4 Torr and is of a modular design to cover increasingly larger areas. DLC films have been grown for the first time using CH4 by this technique. The effect of source to substrate distance on the deposition rate and uniformity of the films has been studied at varying power to the source using C2H2 gas. The films are found to be hard and they adhere well to 7059 glass, quartz, silicon, Mo, and Mylar substrates. Though the deposition rate increases with increasing power and with increasing carbon to hydrogen ratio of the hydrocarbon feedstock, the material properties are relatively independent of the type of hydroc...

Filtered saddle field fast atom beam deposition of diamondlike carbon films

An innovation to separate out ionic and neutral radicals from the beam coming out of a saddle field fast atom beam (FAB) source is reported. Diamondlike carbon (DLC) films were grown simultaneously by these ionic and filtered neutral radicals using methane (CH4) as the source gas in the FAB source, on to the substrates placed at different positions inside the deposition chamber. Faraday cup measurements carried out on the two beams confirm the separation of ionic and neutral radicals. It was found that the DLC films deposited by neutral radicals have higher hardness values (980–1070 kg/mm2) than those deposited by ionic radicals (810–970 kg/mm2), whereas, the values of optical band gap and refractive index are found to be higher in DLC films deposited by ionic radicals than those deposited by neutral radicals. It is emphasized that during normal operation of a saddle field source, to grow DLC films, one essentially has a mixed deposition with contributions both from neutral and ionized radicals. Higher ha...

Electron field-emission from diamond-like carbon films grown by a saddle field fast atom beam source

This article reports electron field-emission measurements on hydrogenated amorphous carbon [diamond-like carbon (DLC)] films grown by aspirating CH4+N2 gas mixtures into a saddle field fast atom beam source. The electron field-emission behavior of these films is discussed in light of varying power, substrate bias, nitrogen dilution, and film thickness. Specifically, changes in the residual stress and hardness of these films are also estimated. The threshold field (Eturn ON) for electron emission shows a minimum at 3.5 V/μm in DLC films grown with 32 W power applied to the source, which is further reduced to 2.7 V/μm, when a positive bias of 100 V is applied to the substrates. Nitrogen dilution of the feedstock is found to reduce the Eturn ON further and it shows a minimum at 2.4 V/μm at ∼27% nitrogen dilution beyond which the value of Eturn ON is found to increase. Emission current density of ∼1 mA/cm2 has been observed at 4.7 V/μm in these nitrogenated DLC films (at ∼27% nitrogen dilution). Further it ha...

Cold plasma processing for some novel material development

Versatility of cold plasma processing has made its deployment in numerous fields possible and is now seen as a vehicle for creation of wealth. In this paper we show how it has been successfully used in high rate deposition of device quality amorphous Hydrogenated Silicon thin films, stress relived Diamond Like Carbon (DLC) films, as also in growingGem quality diamondfilms