A study on the flexibility of the hot-filament configuration and its implementation for diamond, boron carbide and ternary alloys deposition

This paper presents an experimental report on the conditions to grow films with variable composition in the Ta-B-C triangle using the hot-filament (HF) configuration. The HF-Chemical Vapor Deposition (HFCVD) mode is when the precursors for film growth are obtained exclusively from the gas-phase species. Diamond films were produced by feeding the growth system with hydrogen-diluted methane, β-boron films by substituting the methane fraction with diborane, and boron carbide using mixtures of both gases. A second operational mode is achieved when filament sublimation is allowed. In this HF-Physical Vapor Deposition (HFPVD) mode the species stemming from filament and reacting with the gas-atmosphere are the precursors for film growth. The deposition of TaC and TaBC films by means of Ta filaments is reported. A very versatile mode was found when the conditions are adapted during the period of the deposition, switching from PVD to CVD to grow diamond on in-situ deposited TaC.