ELECTRICAL-CONDUCTIVITY OF COMBUSTION-FLAME SYNTHESIZED DIAMOND

The electrical conductivity, from room temperature to 1000-degrees-C, of combustion flame synthesized diamond films and free-standing diamon d slabs are demonstrated to be up to two orders of magnitude lower tha n that of type IIa natural diamond crystals. The low conductivity, ind icative of high purity, has been achieved at diamond growths rates of 5-10 mum/h, considerably higher than that achievable with other diamon d synthesis techniques. These high growth rates have been achieved ove r areas of 5 cm x 5 cm and both thin (10 mum) films on silicon substra tes and thick (approximately 80 mum), free-standing diamond slabs exhi bit similar electrical behavior. The high purity of this diamond is at tributed to the presence of oxidizing species in the flame ambient whi ch are more effective than hydrogen in removing any nondiamond forms o f carbon and other impurities from the growing diamond film.