Toward the Controlled Synthesis of Hexagonal Boron Nitride Films

Abstract

Atomically smooth hexagonal boron nitride (h-BN) layers have very useful properties and thus potential applications for protective coatings, deep ultraviolet (DUV) emitters, and as a dielectric for nanoelectronics devices. In this paper, we report on the growth of h-BN by a low-pressure chemical vapor deposition (LPCVD) process using diborane and ammonia as the gas precursors. The use of LPCVD allows synthesis of h-BN with a controlled number of layers defined by the growth conditions, temperature, time, and gas partial pressure. Furthermore, few-layer h-BN was also grown by a sequential growth method, and insights into the growth mechanism are described, thus forming the basis of future growth of h-BN by atomic layer epitaxy.

Synthesis of large single-crystal hexagonal boron nitride grains on Cu–Ni alloy

“…On the other hand, the decomposition energy of BN, dehydrogenated derivative of BH 2 NH 2 , drops more evidently by introducing Ni to the Cu substrate. It is apparent that the introduction of Ni can enhance the decomposition of poly-aminoborane, which helps the reactions of desorption or the formation of Ni-B and Ni-N phases 18 , consistent with the weak h-BN growth on Cu-Ni alloy with 30 atom % Ni. To enable growth of h-BN on Cu-Ni alloy with high Ni content, one would have to increase the precursor supply; thus, the growth of h-BN enters into a completely different process window 18,19,21,23,24 .…”

“…However, the flakes are obtained through a highly skilled manual process-mechanical exfoliation and transferring, which is not a scalable method for practical applications. So far, many efforts have been taken on various substrates such as Ni [16][17][18][19][20][21] , Cu 3,[21][22][23][24][25][26][27] , Pt 28,29 , Ru 30,31 and Co 32 to obtain large h-BN crystals via the chemical vapour deposition (CVD) process. However, those grains in h-BN films are very small (usually o50 mm 2 ) because of high nucleation density at the early growth stages 10,11,[15][16][17]19,22 .…”

“…The growth mechanism of h-BN on Cu is mainly surfacemediated 23,25 , while on Ni, it is neither surface-limited nor dominated by segregation and precipitation of B and N, but rather depends on surface chemistry of Ni-B and Ni-N 18 . Our experimental parameters of h-BN growth on Cu-Ni substrate with 10-20 atom % Ni are based on the surface-mediated mechanism on Cu foils.…”

Vertical Transistors Based on 2D Materials: Status and Prospects

“…Although single and multilayer h-BN used for device demonstration are still mainly obtained by exfoliation from the bulk crystal, significant progress has been also made towards the controlled synthesis of large-area, high-quality h-BN films by CVD on metal catalysts, such as Ni [129], Cu [130] and Ni/Cu alloys [131]. Recently, Sonde et al reported a detailed study clarifying the mechanisms of CVD h-BN growth on Ni and Co thin films on SiO 2 /Si substrates [132], which could lead to large area (up to wafer scale) growth of h-BN thin films on arbitrary substrates in a transfer-free manner.…”

Direct chemical conversion of graphene to boron- and nitrogen- and carbon-containing atomic layers

“…Recently, several attempts have been made to build graphene devices on h-BN substrates to exploit their complementary properties [7][8][9][10] . Progress in this direction has been limited by difficulties in achieving scalable growth of uniform h-BN layers using chemical vapour deposition, a technique used to deposit high-quality graphene layers [11][12][13][14][15][16][17][18][19] . There have also been a few attempts to co-deposit graphene and h-BN domains to build hybridized two-dimensional boron carbonitride (h-BNC) atomic layers [10][11][12][13][14][15][16][17][18][19][20][21][22] .…”