Growth of Boron Nitride Thin Films on Silicon Substrates Using New Organoboron Precursors

Abstract

Thin films of BN have been deposited on silicon substrates in the temperature range of 600 to 900 °C by supersonic molecular jet epitaxy and plasma-assisted MOCVD using new organoboron precursors such as borane-triethylamine complex (BTEA) and tris(sec-butyl)borane (TSBB). Hydrogen was used as carrier gas, and additional nitrogen and ammonia as reactive gases were supplied by either through nozzle or via remoted plasma. Crack-free, polycrystalline hexagonal BN films with nano-size crystals were successfully grown at temperature as low as 750 °C using BTEA. With increasing substrate temperatures to 900 °C, however, the h-BN films chenged polycrystalline with smoother surface and larger crystals. The changes of relative film quality with deposition temperature and reactive gas have been confirmed with FTIR. Nitrogen plasma enhanced the film quality and the stoichiometry, and removed the surface carbon effectively rather than ammonia and hydrogen plasmas molecular beam. Wide band gaps were calculated using optical transmittance measurements.