VACANCIES IN POLYCRYSTALLINE DIAMOND FILMS

Positron-lifetime spectroscopy has been performed in concert with phot oluminescence to investigate vacancy-related point defects in polycrys talline diamond films grown by chemical vapor deposition (CVD). Undope d films extensively contain vacancies including monovacancies, divacan cies, and vacancy clusters. They are distributed inhomogeneously throu ghout the films with some crystallites nearly free of vacancies while others contain high concentrations (> 50 ppm). However, boron doping d an dramatically reduce the vacancy content in diamond films. The vacan cy-related defects are stable up to 1100 degrees C. The different lumi nescence peaks can be related to various types of vacancies present in CVD diamond.