The invention discloses a
diameter enlarging growth method of monocrystal
diamond. The
diameter enlarging growth method of monocrystal
diamond comprises following steps: 1, an octagonal high temperature
high pressure diamond substrate is selected, wherein the side surfaces of the octagonal high temperature
high pressure diamond substrate are designed to be alternatively arranged {100}
crystal faces and {110}
crystal faces; 2, a
molybdenum support is introduced into a
reaction chamber, a piece of
gold foil is placed on the
molybdenum support, the octagonal high temperature
high pressure diamondsubstrate is placed on the
molybdenum support, the
reaction chamber is vacuumized, the octagonal high temperature high pressure
diamond substrate is heated in the
reaction chamber until the gold foilis melted, and then the octagonal high temperature high pressure
diamond substrate is welded onto the molybdenum support; 3,
tungsten filaments are placed on a growth platform in the reaction chamber, and the molybdenum support welded with the octagonal high temperature high pressure diamond substrate is placed on the
tungsten filaments for surface defect and injury
etching pretreatment; and 4, the pressure, the temperature,
microwave frequency,
methane concentration, and
growth time in the reaction chamber are controlled, so that growth of monocrystal diamond epitaxial film with a thicknessranging from 0.5 to 2.5mm on the octagonal high temperature high pressure diamond substrate obtained via pretreatment is realized. The
diameter enlarging growth method is capable of reducing the content of polycrystal in the monocrystal diamond epitaxial film, and ensuring diameter enlarging effectiveness, and can be used for manufacturing of diamond
field effect transistors.