The synthesis and characterization of phosphorus-doped diamond films using trimethyl-phosphite as a doping source

Abstract

Producing impurity-doped diamond films is a critical task for modern electronic applications. In this study, the effects of phosphorus in the gas phase on the morphological features of polycrystalline diamond films were investigated. The diamond films were prepared on n-type Si(100) substrates by the microwave plasma chemical vapour deposition. A trimethyl-phosphite vapour was introduced to the CH4-CO2 gas mixture as a dopant source. Surface morphology changed from well-defined facets to ball-like features by increasing the dopant concentration in the gas phase. Phosphorus-doped diamond films of good quality and well defined facets could be obtained by reducing the carbon concentration of reactant gases. This reduction could be achieved by decreasing the CH4 flow rates during the deposition process. An increase in the the dopant source caused the growth rate to become lower, the nucleation density to reduce drastically, and the relative intensity of XRD characteristic (110) peak to increase significantly.