Control of crystallographic orientation in diamond synthesis through laser resonant vibrational excitation of precursor molecules

Abstract

Crystallographic orientations determine the optical, electrical, mechanical, and thermal properties of crystals. Control of crystallographic orientations has been studied by changing the growth parameters, including temperature, pressure, proportion of precursors, and surface conditions. However, molecular dynamic mechanisms underlying these controls remain largely unknown. Here we achieved control of crystallographic orientations in diamond growth through a joint experimental and theoretical study of laser resonant vibrational excitation of precursor molecules (ethylene). Resonant vibrational excitation of the ethylene molecules using a wavelength-tunable CO2 laser steers the chemical reactions and promotes proportion of intermediate oxide species, which results in preferential growth of {100}-oriented diamond films and diamond single crystals in open air. Quantum molecular dynamic simulations and calculations of chemisorption energies of radicals detected from our mass-spectroscopy experiment provide an in-depth understanding of molecular reaction mechanisms in the steering of chemical reactions and control of crystallographic orientations. This finding opens up a new avenue for controlled chemical vapor deposition of crystals through resonant vibrational excitations to steer surface chemistry.

Desorption Flame-Induced Atmospheric Pressure Chemical Ionization Mass Spectrometry for Rapid Real-World Sample Analysis

“…41,43) Figure 2 shows the background ion mass spectrum of an FAPCI source. Since the ion trap analyzer provided poor ion response at low mass range (m/z <50), ] and a series of ions with 14 mass unit di erence (i.e., m/z 57 and 71) were also detected.…”

Bi-Stability and Orientation Change of a Thin α-Fe2O3 Layer on a ε-Fe2O3 (004) Surface

“…5,6 Thus, engineering layer orientation is a potentially efficient method for optimizing the properties of surfaces. 7−11 Controlling the surface orientation can easily be done in a single crystal by cutting a sample in the desired direction. However, this simple approach cannot be applied to a thin film because the substrate predetermines the growth direction.…”

“…Chemical reactions involving a solid, such as a catalytic reaction, occur on the surface. − The performance of such reactions therefore strongly depends on certain surface characteristics such as the surface orientation and surface activity. Because the surface properties can depend on the presence of dangling bonds, i.e., broken chemical bonds, and given that each surface has different number of such bonds, one surface can have quite different chemical activity from another, even in the same material. , Thus, engineering layer orientation is a potentially efficient method for optimizing the properties of surfaces. − Controlling the surface orientation can easily be done in a single crystal by cutting a sample in the desired direction. However, this simple approach cannot be applied to a thin film because the substrate predetermines the growth direction.…”

Effects of Laser Photolysis of Hydrocarbons at 193 and 248 nm on Chemical Vapor Deposition of Diamond Films

“…24 In previous works, the potential of laser chemistry was extended from the study of molecular reactions to practical material synthesis and significant enhancement in diamond growth by introducing infrared (IR) and UV laser irradiations in combustion diamond CVD was achieved. [25][26][27][28][29] In particular, we found that UV photolysis of hydrocarbons effectively suppressed the nondiamond carbon formation in diamond growth. 30 The photodissociation channels and quantum yields are known to be wavelength dependent.…”