CHARGE-TRANSPORT IN HEAVILY B-DOPED POLYCRYSTALLINE DIAMOND FILMS

Temperature-dependent conductivity and Hall measurements have been car ried out on heavily in situ B-doped polycrystalline diamond films in a temperature range from similar to 100 to 750 K. The slope of the cond uctivity is clearly non-Arrhenius leading to a pronounced tail at low temperatures. Carrier transport at low temperatures is dominated by va riable range hopping. The activation energy decreases with increasing doping concentration and the most heavily doped diamond films show met allic behavior above room temperature. Hole carrier concentrations up to 1.8X10(21) cm(-3) were measured in agreement with secondary-ion-mas s spectroscopy investigations.