monolithically integrated nanodiamond vacuum lateral

the field provided by the anode. The modified F-N [4] principle, in triode configuration, with the resultant Vt was used to analyze the emission data, Fig. 2 inset. The result confirms that the emission current is due to tunneling mechanism under applied electric fields. In the second mode of operation the handling Si was used as gate electrode and the other ND electrode as anode, while keeping the fingerlike emitters as cathode. Figure 3 displays the triode I-V characteristics. A larger Ia of ~40 µA was obtained at Va of ~60 V, when the Vg was 10 V. Where as, applying negative 10 V at the gate, suppressed Ia to ~20 µA at same Va. It is believed that the higher current attributes to the position of the gate which is 2 µm closer than the previous case. The total cathode voltage (Vt) was calculated as earlier and the device characteristics were also found to follow the modified F-N relationship, Fig. 3 inset. Further, the applied anode and gate voltages are one of the lowest reported for lateral device, especially with cathode-gate separation in microns. However, these values can be further improved by placing the gate closer to the emitter. It is also important to mention here that the gate-intercepted current is negligible to the anode current of the triode. The analysis based on the modified Fowler-Nordheim theory in triode configuration confirms the field emission mechanism and operating principle of the device. The geometry coefficient associated with the gate screening effect was estimated from the triode amplification factor extracted from the emission characteristics, showing consistency with the modeling results based on electrostatic theory.

IV. CONCLUSION The fabrication process of a monolithic nanodiamond microtriode has been successfully developed. The fabricated device exhibits clear triode behavior of gate- modulated emission current at low operating gate voltages. The analysis of triode parameters provides a viable approach to understand the field emission mechanism of the triode and for further design of the device structure with desired triode performance for vacuum IC.

REFERENCES 1. W. P. Kang, J. L. Davidson, A. Wisitsora-at, Y. M.

Wong, and D. V. Kerns, Diamond and Related Materials, Vol. 13, 11-12, pp. 1944-1948, 2004.

2. C. M. Park, M. S. Lim, and M. K. Han, IEEE Electron Device Lett., Vol. 18, 11 pp. 538, 1997.

3. K Subramanian, PhD dissertation, Department of Electrical Engineering, Vanderbilt University, Nashville, TN, USA, 2008.

4. R. H. Fowler and L. W. Nordheim, Proc. of the Royal Society of London, Series A 119, 173-181, 1928.

Figure 1. SEM of the fabricated nanodiamond triode. Inset shows higher magnification image of the device.

Figure 2. Triode emission characteristics of the nanodiamond lateral device operating in mode 1 (handling Si as anode); Inset shows corresponding F-N plots.

Figure 3. Triode emission characteristics of the nanodiamond lateral device operating in mode 2 (handling Si as gate); Inset shows corresponding F-N plots.

Paper WP-1-6 presented in IEEE Nanotechnology Materials and Devices Conference (IEEE NMDC 2013), October 7-9, 2013, National Cheng Kung University, Tainan, Taiwan.