The influence of film-to-substrate characteristics on the electron field emission behavior of the diamond films

Diamond films possessing large electron field emission properties were obtained using B(OCH3)(3) as dopants in chemical vapor deposition process. The CH4:B(OCH3)(2) ratio and total gas flow rate markedly influenced the emission current density (J(e)) without significantly altering the turn-on electric field (E-0) and effective work function (phi(e)) of the films. The emission current density attainable is (J(e))(Si)=280 mu A/cm(2) (at 20 V/mu m) with (E-0)(Si)=10.2 V/mu m and (phi(e))(Si)=0.0934 eV for the films deposited using CH4:B(OCH3)(3):H-2=18:6:300 sccm. Analysis using Raman spectroscopy revealed that the improvement of the J(e) value could be attributed to the modification on the defect concentration of the films. Precoating an Au layer on Si substrates pronouncedly lowered the turn-on electric field to [(E-0)(Au,Si)=7.1 V/mu m] without markedly altering the effective work function [(phi(e))(Au/Si)=0.0534 eV]. This is ascribed to a modification on the film-to-substrate interface which reduced the conduction barrier for electrons to transplant from substrates to the emission sites, i.e. the diamond surfaces. The emission current density attainable is (J(e))(Au/Si)=700 mu A/cm(2) (at 20 V/mu m). (C) 1998 Elsevier Science S.A.