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

摘要

Diamond films possessing large electron field emission properties were obtained usingB(OCH{sub}3){sub}3 as dopants in chemical vapor deposition process. TheCH{sub}4:B(OCH{sub}3){sub}3 ratio and total gas flow rate markedly influenced the emissioncurrent density (J{sub}e) without significantly altering the turn-on electric field (E{sub}0) andeffective work function (Φ{sub}e) of the films. The emission current density attainable is(J{sub}e){sub}(Si) =280μA/cm{sup}2 (at 20 V/μm) with (E{sub}0){sub}(Si) = 10.2 V/μm and(Φ{sub}e){sub}(Si) = 0.0934 eV for the films deposited usingCH{sub}4:B(OCH{sub}3){sub}3:H{sub}2= 18:6:300 sccm. Analysis using Raman spectroscopyrevealed that the improvement of the J{sub}e value could be attributed to the modification on thedefect concentration of the films. Precoating an Au layer on Si substrates pronouncedly lowered theturn-on electric field to [(E{sub}0){sub}(Au/Si = 7.1 V/μm] without markedly altering the effectivework function [(Φ{sub}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 transport from substrates tothe emission sites, i.e. the diamond surfaces. The emission current density attainable is(J{sub}e)(Au/Si)=700μA/cm{sup}2 (at 20 V/μm).