Properties and texture of B-doped diamond films as thermal sensor

Diamond films have a wide bandgap (5.5 eV), high breakdown voltage (106-107 V cm-1), high electron and hole mobilities (2000 cm2 V-1 s-1 and 1800 cm2 V-1 s-1 respectively), high thermal conductivity (20 W cm-1 k-1) and good thermal sensibility. Therefore, diamond films have a potential application for manufacturing resistance to high-temperature, high-frequency, high-power semiconducting devices, especially high-temperature thermistors. This results in diamond films having wide application prospects in the electronic field. However, diamond films synthesized by the CVD method have high resistivity (about 109-1012 Ω cm) which is undesirable for thermal sensors and semiconductors, so we have studied the growth techniques, texture and properties of B-doped diamond films with low resistivity used for thermal sensors. Diamond films were deposited using MPCVD, and the non-poisonous, stable, easy controlled liquid state boron source (B(CH3O)3) was used for doping. Optimum processing conditions were obtained. B-doped diamond films were characterized morphologically and electrically by scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and secondary ion mass spectrometry. High quality B-doped diamond films with low resistivity have been made. The resistivity of the films is low to 10-1 Ω cm. The B-doped diamond film was used for making a thermistor with good temperature dependence properties. The present work provides a good foundation for the use of diamond films as high temperature semiconductors, and exploits an application for diamond films for the high thermistor made by us.