HOMOEPITAXIAL DIAMOND FILMS CODOPED WITH PHOSPHORUS AND NITROGEN BY CHEMICAL-VAPOR-DEPOSITION

Homoepitaxial diamond films codoped with phosphorus and nitrogen have been grown on natural diamond substrates using phosphine and nitrogen as doping sources by hot-filament chemical-vapor deposition. The exper iments show that the incorporation of nitrogen enhances both the phosp horus incorporation and the film growth rate. The former is attributed to the local lattice dilatation caused by nitrogen, while the latter can be explained by defects induced on the surface of diamond by nitro gen or by a change in gaseous composition. The highest concentrations of phosphorus and nitrogen in the epitaxial films are approximately 3X 10(19) and 6X10(19) atoms/cm(3) respectively, determined by secondary- ion-mass spectrometry; however, these epilayers are highly resistive. Furthermore, cathodoluminescence and photoluminescence studies show th at despite the,variety of luminescence features related to nitrogen, n o indication of phosphorus induced luminescence is found in the infrar ed to visible range. (C) 1995 American Institute of Physics.