ELECTRON FIELD-EMISSION FROM THIN FINE-GRAINED CVD DIAMOND FILMS

The held emission properties of thin, fine-grained diamond films were investigated by measuring emission currents versus electric field curv es. The measurements were performed with a spherical electrode attache d to a piezoelectric positioning system. The lateral distribution was analyzed by accelerating emitted electrons onto a fluorescent screen. In addition the transient behavior of the emission current was investi gated. These characterization techniques were applied to a large numbe r of CVD diamond films deposited by microwave plasma-assisted CVD. The samples were prepared with various methane concentrations (0.5-7%) an d deposition temperatures (700-900 degrees C). Undoped as well as boro n-and nitrogen-doped samples were studied. Under optimized conditions threshold field strengths as low as 2 V/mu m were realized, yielding c urrent densities in the range of several mA/cm(2) at 5 V/mu m. The den sity of emission sites is on the order of 10(4) sites/cm(2). (C) 1997 Elsevier Science S.A.