Search for scaling parameters for growth rate and purity of hot-filament CVD diamond

Abstract For hot-filament CVD of diamond, the roles of the product pt of pressure p and deposition time t , and of the mean residence time t r , have been tested as possible scaling parameters. The film thickness d and quality (from Raman spectroscopy and SEM) were investigated. It was found that neither pt nor t r is a sufficient scaling parameter. With the gas mixture of 82.5% H 2 +0.8% CH 4 +16.7% Ar , appreciable diamond is grown at 40 and 200 mbar, but not at 8 and 400 mbar in the region t r =24–4708 s. All film thickness curves d ( t r ) show a maximum, and the found diamond deposition regions and maxima of diamond purity are situated around these maxima. With increasing pressure, the maxima of d ( t r ) decrease (except at 8 mbar) and lie at higher t r . The film thickness decreases with increasing filament/substrate distance.