High Conductivity Hydrogenated Boron and Silicon Co-Doped Diamond With 0.46 Ω·mm Ohmic Contact Resistance

We report on achieving high conductivity hydrogenated boron (B) and silicon (Si) co-doped diamond with a room-temperature Hall result of a square resistance of 2724 ohm/sq, a sheet hole density of
${3}.{3}\times {10} ^{{13}}$
cm−2, and a hole mobility of 68.9 cm2/Vs. The co-doping of B and Si is realized in such a way. First, etch solid BN disk by hydrogen plasma in microwave plasma chemical vapor deposition (MPCVD) system to form B source, and sputter Si film on the diamond surface, and then etch the Si film on diamond sample by hydrogen plasma at 1000 °C in the same MPCVD chamber, and B/Si diffuse to dope diamond. The secondary ion mass spectroscopy of the sample shows that at a depth of
$0.3~\mu \text{m}$
, the B and Si doping concentration is higher than
${1}.{0}\times {10} ^{{17}}$
cm−3, and the highest B and Si doping concentration at the surface is
${3}.{7}\times {10} ^{{20}}$
cm−3 and
$^{} {1}.{1}\times {10} ^{{20}}$
cm−3, respectively. By using Au to form the ohmic contact electrode, the sample achieves the low ohmic contact resistance of
$0.46~\Omega \cdot $
mm and the contact resistivity of
${1}.{6}\times {10} ^{-{5}}\,\,\Omega \cdot $
cm2. The B and Si co-doped diamond provides a new idea for the ohmic contact process optimization of diamond FET devices.