Magnetoresistance effect of p-type diamond films in various doping levels at different temperatures

The magnetoresistance effect of p-type diamond films has been investigated at different temperature. Diamond films were grown by microwave plasma chem ical vapor deposition. Mirror-polished p-type Si(100) was used as a substra te material. The experimental results show that a notable magnetoresistance effect in polycrystalline and heteroepitaxial semiconducting diamond films was observed. The relative changes in the resistivity of the diamond films with magnetic field strongly depended on both boron-doped concentration in the films and geometric form of the samples. The effect of disk structure was greater than that of strip-type samples, also variation in the resistiv ity of heteroepitaxial diamond films was greater than that of polycrystalli ne diamond films at same magnetic field. The magnetoresistance of p-type di amond films was decreased with increasing both boron-doped concentration an d temperature. The relative changes in resistance of the heteroepitaxial di amond films with the disk structure was increased by 0.85 at room temperatu re under magnetic intensity of 5T, but only 0.40 for strip-type structure. The results are discussed in detail. (C) 2000 Elsevier Science S.A. All rig hts reserved.