Ultraviolet laser photolysis of hydrocarbons for nondiamond carbon suppression in chemical vapor deposition of diamond films

Abstract

In this work, we demonstrate that ultraviolet (UV) laser photolysis of hydrocarbon species alters the flame chemistry such that it promotes the diamond growth rate and film quality. Optical emission spectroscopy and laser-induced fluorescence demonstrate that direct UV laser irradiation of a diamond-forming combustion flame produces a large amount of reactive species that play critical roles in diamond growth, thereby leading to enhanced diamond growth. The diamond growth rate is more than doubled, and diamond quality is improved by 4.2%. Investigation of the diamond nucleation process suggests that the diamond nucleation time is significantly shortened and nondiamond carbon accumulation is greatly suppressed with UV laser irradiation of the combustion flame in a laser-parallel-to-substrate geometry. A narrow amorphous carbon transition zone, averaging 4 nm in thickness, is identified at the film–substrate interface area using transmission electron microscopy, confirming the suppression effect of UV laser irradiation on nondiamond carbon formation. The discovery of the advantages of UV photochemistry in diamond growth is of great significance for vastly improving the synthesis of a broad range of technically important materials.

Laser Synthesis and Microfabrication of Micro/Nanostructured Materials Toward Energy Conversion and Storage

“…It demonstrated that the obtained graphene layer on DLC had comparable conductivity and transparency performances to those of ITO. In addition, Fan et al [ 53 ] used hydrocarbon species including a mixture of acetylene (C 2 H 2 ), ethylene (C 2 H 4 ) and oxygen (O 2 ) as the precursor, a combustion torch was used to produce the flames and an ultraviolet (UV) laser was used to excite the combustion species in the direction of perpendicular to the combustion flames and parallel to the substrate (Fig. 4 a, b).…”

“…4 a Schematic diagram of the optical emission spectroscopy (OES) and laser-induced fluorescence (LIF) setup to characterize the species in the combustion flame with UV laser irradiation. b Schematic illustration of the UV-laser-assisted diamond combustion CVD setup [ 53 ] …”

Laser vibrational excitation of radicals to prevent crystallinity degradation caused by boron doping in diamond

“…Nevertheless, laser chemical control studies have been focused on simple molecular reactions for a long time because of limited choices and high cost of laser sources. The increasing versatility of laser sources and their notably reduced operational cost make it possible to envision their enormous potential for enabling a control in practical applications (11)(12)(13)(14).…”

Raman measurements using a field‐widened spatial heterodyne Raman spectrometer

“…It is a popular method and technique for identification and analysis because it is nondestructive, requires no sample preparation, and both organic and inorganic substances can be measured in various states. Owing to these advantages, Raman spectroscopy has already been applied in a variety of fields, including physics, chemistry, biology, medicine, geology, and electronics . A spatial heterodyne Raman spectrometer (SHRS) possesses the multiple advantages, a larger entrance or higher light throughput than that a dispersion system, high spectral resolution, a compact, and rugged package without moving parts, and is compatible with a pulsed laser and gated detectors under ambient light conditions .…”