Exceptionally high voltage Schottky diamond diodes and low boron doping

Exceptionally pure epitaxial diamond layers have been grown by microwave plasma chemical vapour deposition, which have low boron doping, from 5 × 10 14 to 1 × 10 16 cm −3 , and the compensating n-type impurities are the lowest reported for any semiconducting diamond, <3 × 10 13 cm −3 . The hydrogen impurities that bind with the boron making them electrically inactive can be significantly reduced by baking the diamond to >700 °C for ∼1 s in air. Schottky diodes made on these epitaxial diamond films have breakdown voltages >6 kV, twelve times the highest breakdown voltage reported for any diamond diode and higher than any other semiconductor Schottky diode.