Enhanced Crystallinity of h‐BN Films Induced by Substrate Bias During Magnetron Sputtering

The synthesis of uniform, highly crystalline thin films of hexagonal boron nitride (h‐BN) is an important step for its applications in multilayered devices with other emerging 2D materials. We report on the growth of high purity h‐BN by reactive magnetron sputtering from a pure B target in an Ar/N2...

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Bibliographic Details
Published in:physica status solidi (b) 2018-03, Vol.255 (3), p.n/a
Main Authors: Stewart, David M., Lad, Robert J.
Format: Article
Language:English
Subjects:
2D materials
crystallinity
hexagonal boron nitride
substrate biasing
surface morphology
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Summary:The synthesis of uniform, highly crystalline thin films of hexagonal boron nitride (h‐BN) is an important step for its applications in multilayered devices with other emerging 2D materials. We report on the growth of high purity h‐BN by reactive magnetron sputtering from a pure B target in an Ar/N2 plasma. Enhanced h‐BN crystallinity on Ni substrates was achieved using a negative DC substrate bias during deposition, which served to increase the energy of incident ions, causing higher adatom mobility and re‐sputtering of weakly bound species on the growth surface. Growth rates between 0.002 to 1.1 Å s−1 were observed as the power was varied from 10 to 200 W and the growth temperature was either room temperature or 850 °C. BN films grown on a r‐sapphire substrate or a silicon (100) wafer with native oxide were smooth but amorphous under all conditions. Crystalline growth was observed on unbiased Ni foil substrates heated to 850 °C provided the growth rate was below 0.01 Å s−1, but the films were a non‐uniform mixture of h‐BN crystals and a disordered phase. Using a −50 V substrate bias, a high degree of h‐BN crystallinity and film homogeneity over large areas on the Ni substrate was achieved. The growing importance of hexagonal boron nitride (h‐BN) for two‐dimensional devices requires new techniques for its growth. The use of substrate biasing during reactive magnetron sputtering allows control over the ion energy incident on the growth surface, and enables the growth of h‐BN films with substantially improved morphology and crystallinity at higher growth rates.
ISSN:0370-1972
1521-3951
DOI:10.1002/pssb.201700458