Semiconducting Diamonds by Ion Bombardment

Abstract

Both natural and synthetic diamond crystals acquire altered surface layers as the result of ionic bombardment in a glow discharge at potentials of 1500-2800 V. The surface layers have a gray-brown color, and electron diffraction patterns of them indicate that they are somewhat amorphous. The surface layers are found to be electrical semiconductors. The kinds of gas ions used for bombardment apparently determine whether the conductivity is predominantly $n$ type or $p$ type. The activation energies for conduction range between 0.024 and 0.20 eV. The surface layers are partly destroyed by heating in air to about 400°C.