Piezoresistive Property of CVD Diamond Films

Piezoresistive properties of chemical vapor-deposited boron-doped p-type polycrystalline diamond films were investigated. The p-type polycrystalline diamond films of about 2 μm thickness were grown on SiO2/Si substrate using a hot-filament reactor. Effective carbon concentration, defined as (C-O)/H, was varied from 2.2 to 5.5 %, and boron to carbon ratio was kept constant. Gauge factor for the p-type diamond piezoresister decreased with carbon to hydrogen ratio. The quality of the diamond films were examined by using a scanning electron microscope (SEM), Raman spectroscopy and X-ray diffraction. The diamond films were degraded with the (C-O)/H.