Freestanding (100) homoepitaxial CVD diamond

The interest in freestanding, low defect density, single crystalline CVD diamond films for electronic applications led to several studies of homoepitaxial CVD diamond growth. The aim of our work is to obtain nearly atomically flat surfaces even for several hundred microns thick CDV diamond films by controlling the growth mechanism on (100) surfaces.The effect of pre-growth etching of the substrate with a O2/H2 plasma and the influence of a high methane concentration on the growth on type Ib (100) HPHT synthetic diamonds were investigated. Using a MW PE CVD ASTeX PDS17-5 kW reactor at a pressure of about 180 Torr and temperatures typically around 700 °C, CVD diamond films were grown. A precise control of the growth mechanism led to the preparation of optical quality freestanding monocrystalline CVD diamond films of 600 μm thickness, practically free of hillocks and unepitaxial crystallites, with a relatively high growth rate of 4 to 5 μm/h. These films were characterized by optical microscopy, AFM, SEM and Raman spectroscopy. It is shown that even the thickest films have a mean roughness (Rms) remaining as low as 1 nm for a scanning area of 5 × 5 μm2.