In the present investigation, a nitrogen-doped multilayer homoepitaxial single crystal\ndiamond is synthesized on a high-pressure high temperature (HPHT) Ib-type diamond substrate\nusing the microwave plasma chemical vapor deposition (MPCVD) method. When 0.15 sccm of\nnitrogen was added in the gas phase, the growth rate of the doped layer was about 1.7 times\nthat of the buffer layer, and large conical and pyramidal features are formed on the surface of the\nsample. Raman mapping and photoluminescence imaging of the polished cross sectional slice shows\na broadband emission, with a characteristic zero phonon line (ZPL) at 575 nm in the doped layers,\nand large compressive stress was formed in the nitrogen-doped layers. X-ray topography shows\nthat the defects at the interface can induce dislocation. The pyramid feature is formed at the defect,\nand more nitrogen-related defects are formed in the pyramid region. Thin nitrogen-doped multilayers\nwere successfully prepared, and the thickness of the nitrogen-doped and buffer layers was about\n650 nm each. The indentation measurements reveal that the thin nitrogen-doped multilayers are\nultra-tough (at least ~22 MPa m1/2), compared to the Ib-type HPHT seed substrate (~8 MPa m1/2) and\nthe unintentionally doped chemical vapor deposition (CVD) single crystal diamond (~14 MPa m1/2).
Loading....