Synthesis of large-area and high quality borophene on Ir(111) via thermal catalytic decomposition of borazine (B3H6N3)

Abstract

Preparation of borophene has been performed by deposition from an e-beam heated high-purity boron rod via molecular beam epitaxy (MBE). However, the MBE technique is very expensive with low yield and most of all, epitaxially grown borophene islands are found to be in nanometer sized. Here we report on the first successful growth of large area borophene via the thermal catalytic decomposition of borazine (B₃H₆N₃) on an Ir(111) substrate at high temperatures using conventional CVD technique. The observed growth mode is described to be similar with boron dissolving into the bulk at high temperatures and segregating to the surface forming large borophene sheets as the sample is cooled. The surface morphology and structure determination has been performed using in-situ by real-time growth observation via low energy electron microscopy (LEEM) and high-resolution spot profile analyzing-LEED (SPA-LEED). To gain insight in its atomic structure and its electronic properties a high-resolution scanning tunneling microscopy and spectroscopy (STM/STS) has been employed. The chemical composition has been determined ex-situ by X-ray photoemission spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) measurements.