P-type diamond layers were produced in polycrystalline diamond by means of rapid thermal diffusion of boron. Using thin film of deposited boron as the source and temperatures near 1600C, solid-state diffusion of boron was achieved, forming conducting layers with average sheet resistances of about 356Ω/square and diffused-layer thicknesses of about 0.6μm. Ohmic contacts to the diffused layers were formed by depositing molybdenum films before the rapid thermal diffusion step so that sintering of contacts occurred simultaneously with the diffusion. The advantages of this approach were that (a) low contact resistances were obtained and (b) only one high-temperature step was involved. Using this technique, molybdenum-diamond Schottky diodes were fabricated and found to have barrier potentials of 2.6V and ideality factors of 1.6.

p-Type Polycrystalline Diamond Layers by Rapid Thermal Diffusion of Boron. Krutko, O.B., Kosel, P.B., Wu, R.L.C., Fries-Carr, S.J., Heidger, S., Weimer, J.: Applied Physics Letters, 2000, 76[7], 849-51