Role of hydrogen carrier gas on the growth of few layer hexagonal boron nitrides by metal-organic chemical vapor deposition

Abstract

Few layer hexagonal boron nitride (h-BN) films were grown on 2-inch sapphire substrates by using metal-organic chemical vapor deposition (MOCVD) with two different carrier gases, hydrogen (H2) and nitrogen (N2). Structural, optical and electrical properties of the MOCVD-grown h-BN films were systematically investigated by various spectroscopic analyses and electrical conduction measurement. Based on the experimental findings including narrower X-ray photoelectron spectra, reduced intensity of the shoulder peaks in near edge X-ray absorption fine structure spectra, and decreased electrical conduction by more than three orders of magnitude when H2 carrier gas is employed, it was concluded that H2 has an advantage over N2 as the carrier gas for MOCVD growth of h-BN which is attributed to the healing of crystalline defects by etching and regrowth processes occurring under the pulsed source-injection mode.

Improvements in structural and optical properties of wafer-scale hexagonal boron nitride film by post-growth annealing

“…In addition, NEXAFS spectra as function of X-ray incident angle, defined as the angle between the polarization angle of the incident X-ray beam and the surface normal to the h-BN films, were measured in order to estimate the average tilt angle of the h-BN films as shown in Fig. 4 by using the following equation 26,46 :where, I is the intensity of X-ray absorption due to transition from 1s core-level to π* anti-bonding states, C is a constant, P is the degree of polarization, which is determined to be 0.85 by the experimental equipment, is the polarization angle of the incident X-ray beam, and α is the average tilt angle. The average tilt angle quantifies that how much the sp 2 -bonded layer material is aligned parallel to the surface, and it is strongly depends on the change in intensity of the transition from 1s core level to π* anti-bonding states at different X-ray incident angles.…”

“…The average tilt angle quantifies that how much the sp 2 -bonded layer material is aligned parallel to the surface, and it is strongly depends on the change in intensity of the transition from 1s core level to π* anti-bonding states at different X-ray incident angles. In the case of perfectly aligned layered materials parallel to the surface, the average tilt angle is 0° as a result of no observed π* peak at the X-ray incident angle of 90°, and it increases as the amount of structural imperfection increases 25,26 . Figure 4c,d are the angle-dependent NEXAFS B K-edge spectra for the as-grown and the post-annealed h-BN films, respectively.…”

“…h-BN films were grown on 2-inch double side polished sapphire substrates by using a commercial MOCVD system at 1050 °C under reactor pressure of 30 mbar with H 2 carrier gas. A pulsed source-injection mode 25,26 composed of 4 steps in a single pulse cycle; injection of 10 sccm triethylborane (TEB) for 4 seconds, interruption for 2 seconds, injection of 8,000 sccm NH 3 for 4 seconds, and interruption for 2 sections was used. Total pulse cycles of 200 resulted in the growth of 9 ~10 layers of h-BN.…”

A Review on the Synergistic Features of Hexagonal Boron Nitride (White Graphene) as Adsorbent‐Photo Active Nanomaterial

“…The carrier gas also plays a crucial role in the growth of h‐BN via CVD by influencing the surface morphology, growth rate, and crystallinity. h‐BN with greater thickness and crystallinity were formed when hydrogen was introduced as a carrier gas whereas, the utilization of nitrogen reduced the crystallinity and thickness by introducing a large number of defects . Further, the nucleation of triangular domains is encouraged due to the active participation of nitrogen .…”

Wafer-scale and selective-area growth of high-quality hexagonal boron nitride on Ni(111) by metal-organic chemical vapor deposition

“…investigated the effects of temperature, pressure, and V/III ratio on the MOCVD growth of h-BN on sapphire and its self-terminating behavior 18,19 . Recently, wafer-scale uniform growth of h-BN films on sapphire was reported, in which the effects of reactor pressure and types of carrier gas were investigated 20,21 . However, MOCVD-grown h-BN films on inert sapphire substrates have not progressed to a reliable quality for practical applications because extremely high temperatures greater than 1400 °C are typically required to obtain a high-quality film 22–24 .…”