Effect of N2O on high-rate homoepitaxial growth of CVD single crystal diamonds

Various gases such as N2, O2, and CO2 have been introduced in the typical reaction atmosphere of CH4/H2 and proposed to improve the growth of chemical vapor deposited (CVD) single-crystal diamonds (SCDs). In this paper, we study the influence of a new adding gas nitrous oxide (N2O) on the growth rate, morphology, and optical properties of homoepitaxy (100) CVD SCDs. The reaction pressure (H2/CH4 flow rates) was fixed at 300 Torr (750/90 in sccm) with the addition of a small amount of N2O gas varied at flow rates of 0, 2, 5, 8 and 10 sccm. With the appropriate addition of N2O, the growth rate was increased up to 135 μm/h and the surface roughness was decreased to around 2 nm. Furthermore, adding N2O is favorable for inhibiting the generation of large anti-pyramidal pits on the top surface of SCDs, which generally appeared in the products synthesized in CH4/H2 ambient. The combined effect of the nitrogen- and oxygen-related radicals decomposed from N2O on the growth and properties of the CVD SCDs is discussed. As a result, the addition of N2O provides a new route to realize high-rate growth CVD SCDs instead of the traditional nitrogen.

► High-rate homoepitaxial growth of CVD single crystal diamonds (SCDs) has been investigated with adding N2O in the conventional gas mixture of CH4/H2. ► The high quality CVD SCDs have been achieved at high growth rates with proper N2O introduction. ► The morphology and crystallography properties of CVD SCDs were related to the varying flow rate of N2O. ► The combined nitrogen- and oxygen-related radicals decomposed from N2O strongly influence the growth and properties of the CVD SCDs.