Carbon nano dots scale by focused ion beam system for MIS diode nano devices

Metal–insulator–semiconductor (MIS) structures with a nanocrystal carbon (nc-C) embedded in SiO2 thin films were fabricated using a focused ion beam (FIB) system with a precursor of low-energy Ga+ ion and carbon source. The crystallinity of nc-C was investigated by Raman spectroscopy and atomic force microscopy (AFM). Raman spectra indicate the evidence of crystallization of nc-C after annealed at 600 °C by the sharp peak at 1565 cm−1 in graphite (sp2), while no peak of diamond (sp3) could be seen at 1333 cm−1. The AFM images showed the nc-C dots controlled with diameter of 100 nm, 200 nm and 300 nm, respectively. The above results revealed that the nc-C dots had sufficiently stuck onto SiO2 films. The hysterisis loop in the capacitance–voltage characteristics appeared in the MIS device with SiO2/nc-C/SiO2 structure in which voltage shift is 0.32 V for radical oxidation and 0.14 V for dry oxidation, respectively.