Bias-enhanced nucleation and growth processes for improving the electron field emission properties of diamond films

Abstract

The evolution of diamond films in bias-enhanced-nucleation (BEN) and bias-enhanced-growth (BEG) processes was systematically investigated. While the BEN process can efficiently form diamond nuclei on the Si substrates, BEG with large enough applied field (> –400 V) and for sufficiently long periods (>60 min) was needed to develop proper granular structure for the diamond films so as to enhance the electron field emission (EFE) properties of the films. For the films BEG under −400 V for 60 min (after BEN for 10 min), the EFE process can be turned on at a field as small as 3.6 V/μm, attaining a EFE current density as large as 325 μA/cm2 at an applied field of 15 V/μm. Such an EFE behavior is even better than that of the ultrananocrystalline diamond films grown in CH4/Ar plasma. Transmission electron microscopic examination reveals that the prime factor enhancing the EFE properties of these films is the induction of the nano-graphite filaments along the thickness of the films that facilitates the transport of electrons through the films.

Origin of graphitic filaments on improving the electron field emission properties of negative bias-enhanced grown ultrananocrystalline diamond films in CH4/Ar plasma

“…It is to be indicated that in CH 4 /H 2 plasma, the bias current required at least 7.5 min to reach a saturated value after the application of À400 V bias voltage. 26 The saturated bias current in the BEG period was proportional to the bias voltage applied [solid squares, Fig. 1(b)] and reached 270 mA/cm 2 for À200 V bias voltage.…”

“…In addition, Teng et al 26 reported the enhanced EFE behavior of bias-enhanced grown (BEG) nanocrystalline diamond (NCD) films using CH 4 CH 4 /H 2 plasma and the feasibility of bias enhanced growth of UNCD films using CH 4 /Ar plasma has not been reported yet.…”

Structural modification of nanocrystalline diamond films via positive/negative bias enhanced nucleation and growth processes for improving their electron field emission properties

“…These curves reveal that the application of negative bias voltage is more effective in lowering the turnon field for inducing the EFE processes. However, the EFE properties of both the beg-NCD À300V and the beg-NCD þ200V films are still better than those attainable for beg-MCD, 15 which has a large E 0 value of 17.7 V/lm when grown under a À300 V bias voltage (closed hexagon symbol, Fig. 7(c)).…”

“…13,14 The formation of sp 2 bonded graphitic phases at the grain boundaries, which create conduction channels for the electrons to get transported, accounts for the improved EFE properties. 15 In contrast, the application of a positive bias voltage enhances the rate of growth of the diamond films as well as growth of grains in the favored orientation. [16][17][18] However, the reports on the effect of positive and negative bias voltages on modifying granular structure of diamond films are controversial.…”

О Возможности Разращивания Алмазов В Среде Углеводородов

“…К настоящему времени для их приготовле-ния используются в основном термическое разложение метана в электрическом поле методами " горячей ни-ти" [1], физическое осаждение из пара в микроволно-вой плазме [2][3][4] и развиваемый нами способ пиролиза метана в зазоре между двумя углеродными пластинами, между которыми создается разность электрических по-тенциалов [5][6][7].…”