Determination of the optical bandgap of the Bernal and rhombohedral boron nitride polymorphs

<div>Epitaxial rhombohedral boron nitride films were deposited on ZrB<sub>2</sub>(0001)/4H-SiC(0001) by chemical vapor deposition at 1485 °C from the reaction of triethylboron and ammonia and with a minute amount of silane (SiH<sub>4</sub>). X-ray diffraction (XRD) φ-scans yield the epitaxial relationships of 𝑟−𝐵𝑁(0001)∥𝑍𝑟𝐵2(0001) out-of-plane and 𝑟−𝐵𝑁(1120)∥𝑍𝑟𝐵2(1120) in-plane. Cross-section transmission electron microscopy (TEM) micrographs showed that epitaxial break down of r-BN film occurs approximatively after 10 nm, above which epitaxial growth proceeds only in limited area up to 80 nm of film thickness. Both XRD and TEM demonstrate the formation of carbon- and nitrogen-containing cubic inclusions at the ZrB<sub>2</sub> surface. Quantitative analysis from X-ray photoelectron spectroscopy of the r-BN films shows B/N ratios between 1.30 to 1.20 and an O content of 3 to 4 at.%. Plan-view scanning electron microscopy (SEM) images reveal a surface morphology where an amorphous material comprising B, C, and N is surrounding the epitaxial twinned r-BN crystals. SiH<sub>4</sub> exposure prior to growth was found to reduce the amount of the amorphous phase on the surface. Defects such as pitting were also observed on the ZrB<sub>2</sub> template surface.</div><div><br></div>

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Determination of B2O3 in Boron Nitride by Volumetric Titration

Proceedings of the 2017 5th International Conference on Mechatronics, Materials, Chemistry and Computer Engineering (ICMMCCE 2017) ◽

10.2991/icmmcce-17.2017.11 ◽

2017 ◽

Author(s):

Ying Li ◽

Yong Shen ◽

Chen Gong ◽

Bentao Li ◽

Hui Huang ◽

...

Keyword(s):

Boron Nitride ◽

Volumetric Titration

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Thermal Chemical Vapor Deposition of Epitaxial Rhombohedral Boron Nitride from Trimethylboron and Ammonia

10.26434/chemrxiv.7447397 ◽

2018 ◽

Author(s):

Laurent Souqui ◽

Henrik Pedersen ◽

Hans Högberg

Keyword(s):

Chemical Vapor Deposition ◽

Boron Nitride ◽

Vapor Deposition ◽

Chemical Vapor ◽

Epitaxial Relationship ◽

Out Of Plane ◽

Α Al2o3 ◽

Favorable Conditions ◽

Relationship Of ◽

Rhombohedral Boron

Epitaxial rhombohedral boron nitride films were deposited on α-Al2O3(001) substrates by chemical vapor deposition, using trimethylboron, ammonia, and with a low concentration of silane in the growth flux. The depositions were performed at temperatures from 1200 to 1485 °C, pressures from 30 to 90 mbar and N/B ratios from 321 to 1286. The most favorable conditions for epitaxy were: a temperature of 1400 °C, N/B around 964, and pressures below 40 mbar. Analysis by thin film X-ray diffraction showed that most deposited films were polytype-pure epitaxial r-BN with an out-of-plane epitaxial relationship of r-BN[001]∥ w-AlN[001]∥ α-Al2O3[001] and with two in-plane relationships of r-BN[110]∥ w-AlN[110]∥ α-Al2O3[100] and r-BN[110]∥ w-AlN[110]∥ α-Al2O3[1̅00] due to twinning.

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