Growth and characterization of near-atomically flat, thick homoepitaxial CVD diamond films

Diamond films were grown in an ASTeX MW PE CVD reactor. The effect of pre-growth etching with a O-2/H-2 plasma and the influence of the methane concentration on growth on type Ib (100) HPHT synthetic diamonds were investigated. By controlling step flow growth we were able to prepare optical quality thick diamond films, free of hillocks and unepitaxial crystallites, with a relatively high growth rate of 4 to 5 mu m/h using higher pressures and methane concentrations than standard growth conditions in combination with a modified substrate holder. All diamond films were characterized by optical microscopy, SEM, AFM and Raman spectroscopy. The mean roughness (Rms) of the films grown with a thickness of 120 mu m was approximately 0.5 to 0.8 nm for scanning regions of 5 x 5 mu m(2). For the first time nearatomically flat films thicker than 200 mu m could be prepared.