Enhanced field emission and patterned emitter device fabrication of metal-tetracyanoquinodimethane nanowires array
Introduction
Over the past few years, one dimensional (1D) nanostructures have been considered as promising field emitters to fabricate field emission displays (FEDs) because of their high enhancement factor owing to the sharp tips and high aspect ratios [1]. Among them, carbon nanotubes (CNTs) [2], [3], [4] have obviously attracted the most attention due to their high aspect ratio and conductivity. These years, metal oxide 1D nanostructures such as ZnO [5], WO3 [6] and CuO [7] have been considered as appropriate alternatives to CNTs for field emission (FE) microelectronic devices owing to their higher thermal and chemical stability and negative electron affinity. However, the synthesis of these nanostructures all requires high-temperature treatments as described in Table 1, which is not conducive to the emission cathode fabrication and FE device packaging. Therefore, it is essential to seek low-temperature-synthesized emission material and to develop convenient counterpart cathode fabrications, which are curial for FE microelectronic device application.
The 1D nanostructures of metal-tetracyanoquinodimethane (M-TCNQ) charge transfer complexes attracted increasingly interests for potential application in functional nano-scaled electronic devices due to their high densities of charge carriers and field-induced electrical switching properties [8], [9], [10], [11]. Recently, studies have revealed that M-TCNQ (e.g., Ag-TCNQ and Cu-TCNQ) nanostructures grown on Ag/Cu foils by organic vapor–solid-phase reaction at 150 °C have low emission turn-on field and mA/cm2 order emission current density [12]. However, the research on FE device application of M-TCNQ nanowires including electrode patterning and substrate facilitating is still insufficient and necessary.
In this paper, Ag(TCNQ) and Cu(TCNQ) nanowires were produced via an undemanding vapor-transport reaction method at a temperature of 100 °C. The field emission properties of as-obtained nanowires were studied. Furthermore, a structure consisting of M-TCNQ nanowires/Metal thin film/ITO glasses was employed in order to reduce the emission threshold field and enhance the emission current. Field emitter device was then fabricated utilizing this structure. The emission fluorescence experiment afterwards indicates that M-TCNQ 1D nanostructures are promising candidates for field emission display (FED) cathode materials.
Section snippets
Experimental
Horizontal oriented M-TCNQ nanowires arrays were synthesized via a vapor-transport reaction method we developed in previous work [13]. A 10 nm thick Cu or Ag film was pre-deposited on the ITO glass substrate by thermal evaporation. Afterwards the substrate together with TCNQ powder (98% Aldrich) was placed in a glass tube connected to a vacuum chamber. After pumped down to 2 × 10−3 Pa, the tube was sealed and thermal treated in a furnace at 100 °C for 1 h. Consequently, the substrate was covered with
Results and discussion
The morphologies of as-prepared M-TCNQ nanowires are shown in Fig. 1. The typical diameters of nanowires ranged from 50 to 200 nm, which was determined by the thickness of the pre-cursor metal film. It can be seen that Ag(TCNQ) nanowires were straight and rigid rod-like (Fig. 1a and b) while Cu(TCNQ) nanowires were bendy and flexible (Fig. 1c and d). The growth of M-TCNQ nanowires conformed to a vapor–liquid–solid mechanism as was discussed in our previous work [13]. During the growth, the metal
Acknowledgements
The authors acknowledge financial support from Shanghai Science and Technology Development Fund (No. 09DZ1142102 and No. 0752nm016) and Shanghai Leading Academic discipline Project (No. B113).
References (18)
- et al.
Micron
(2005) - et al.
J. Solid State Chem.
(2000) - et al.
Science
(1995) - et al.
Appl. Phys. Lett.
(1999) - et al.
Appl. Phys. Lett.
(2001) - et al.
Appl. Phys. Lett.
(2000) - et al.
Appl. Phys. Lett.
(2004) - et al.
Appl. Phys. Lett.
(2007) - et al.
J. Appl. Phys.
(2007)