Preparation of polycrystalline boron carbide thin films at room temperature by pulsed ion-beam evaporation

Abstract

Polycrystalline boron carbide (B4C) thin films have been prepared by a pulsed ion-beam evaporation technique without heating substrates or annealing samples. Here, we clearly demonstrate the possibility of preparing B4C thin films for electronic device applications.

The local physical structure of amorphous hydrogenated boron carbide: insights from magic angle spinning solid-state NMR spectroscopy

“…Electric field gradient (EFG) parameters were also calculated, from which were determined the quadrupole coupling constants (Q cc ) and their associated asymmetry parameters (η). All C nuclei were specified as 13 13 C chemical shifts for ortho-, meta-, and paracarborane (1a-c) are all within 1 ppm of the experimental shifts [66], while the calculated 11 B shifts for orthocarborane are only slightly upfield (2-4 ppm) from the experimental shifts. Similar differences are observed for the experimentally known compounds 5b and 5c [67].…”

“…Owing to their unique chemical, electrical, thermal, and mechanical properties, boron-rich carbide (BC) thin films have generated significant interest as heterostructure materials in high-temperature thermoelectric energy converters [1][2][3][4], as low-k dielectric materials for ultra-large-scale integrated circuits [5,6] and as p-type semiconductors for directconversion solid-state neutron detectors [7]. Of the many methods developed for the fabrication of BC films [8][9][10][11][12][13][14], the plasma-enhanced chemical vapour deposition (PECVD) of BC from the sublimed vapour of the single-source solid precursor orthocarborane (1,2-C 2 B 10 H 12 , 1a) stands out as a reliable route to high-resistivity (10 10 -10 13 cm) devicequality films [15][16][17][18][19][20][21]. This method produces hydrogenated B x C:H y films with a relatively narrow range of B x C stoichiometries (x ≈ 2-5) (compared to the wider range possible when using individual C-and B-containing precursors) [11], which do not show evidence of segregated carbon phases known to reduce bulk electrical resistivity [22] as commonly observed in BC films prepared by other methods [23][24][25][26][27].…”

Tuning the properties of a complex disordered material: Full factorial investigation of PECVD-grown amorphous hydrogenated boron carbide

“…However, more often than not, such efforts lack sufficient direction and many years are required for applications to come to fruition. In the case of a-B x C:H y , dozens of materials growth and characterization studies have been published [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47], but because these have covered such a wide range of growth methods and resulting a-B x C:H y variants, and because these typically only focus on one or a small number of process conditions or properties at a time, they fail to provide a comprehensive picture of the process-property landscape for this entire material family or any specific variant. One fabrication method that has gained traction, particularly for device applications, is the plasma-enhanced chemical vapor deposition (PECVD) of a-B x C:H y using a single-source molecule-based ortho-carborane (o-C 2 B 10 H 12 ) precursor [48][49][50][51][52][53][54][55][56][57].…”

The influence of hydrogen on the chemical, mechanical, optical/electronic, and electrical transport properties of amorphous hydrogenated boron carbide

“…The problem with employing such bulk growth techniques for the specialized semiconductor device applications described above is that they require harsh fabrication conditions, demonstrate limited tunability, and tend to yield unfavorable electronic properties such as unacceptably high electrical conductivity. 26,27 It has been demonstrated [28][29][30][31][32][33][34] that the use of thin-film fabrication methods such as chemical vapor deposition or physical vapor deposition can produce B x C thin films that maintain robust mechanical, thermal, and chemical properties, while improving on electrical transport, electronic, and/or optical properties (e.g., resistivity and band gap), without having to resort to the extreme conditions required by traditional bulk growth techniques. In particular, the plasma-enhanced chemical vapor deposition (PECVD) of films from ortho-carborane (o-C 2 B 10 H 12 ), which typically yields amorphous hydrogenated boron carbide (a-B x C:H y ) when lower growth temperatures are used, has been shown to be suitable for producing films for device applications as well as conducive to tuning properties over a wide range.…”