Enhancement in field emission current density of Ni nanoparticles embedded in thin silica matrix by swift heavy ion irradiation

Abstract

The field emission (FE) properties of nickel nanoparticles embedded in thin silica matrix irradiated with 100 MeV Au+7 ions at various fluences are studied here. A large increase in FE current density is observed in the irradiated films as compared to their as deposited counterpart. The dependence of FE properties on irradiation fluence is correlated with surface roughness, density of states of valence band and size distribution of nanoparticles as examined with atomic force microscope, X-ray photoelectron spectroscopy, and grazing incidence small angle x-ray scattering. A current density as high as 0.48 mA/cm2 at an applied field 15 V/μm has been found for the first time for planar field emitters in the film irradiated with fluence of 5.0 × 1013 ions/cm2. This significant enhancement in the current density is attributed to an optimized size distribution along with highest surface roughness of the same. This new member of field emission family meets most of the requirements of cold cathodes for vacuum micro/nanoelectronic devices.

Mechanistic details of the formation and growth of nanoscale voids in Ge under extreme conditions within an ion track

“…Moreover, glancing incidence smallangle x-ray scattering (GISAXS) is an effective means to quantify the growth dynamics of voids in terms of dimensions in both in-plane and out-of-plane orientations. GISAXS technique is well established and widely used to study formation and modification of nanostructures especially by ion beams [23][24][25]. This technique is suitable to study nano porous structures as X-ray scattering is highly sensitive to contrast of electron density in medium [26].…”

Evidence of local structural influence on the shape driven magnetic anisotropy in electronically excited Ni nanoparticles embedded in SiO2 matrix

“…This magnetic behaviour in irradiated metal-insulator films is a manifestation of micro-structural and electronic structural properties. After initial reduction in Ni (111) peak height due to irradiation induced disordering 25 , not many changes are observed in the XRD pattern of other films irradiated at different fluences. Thus long-range ordering is not playing very crucial role in magnetic results obtained herein.…”

“…The as deposited and annealed films were then subjected to different fluences (1 × 10 13 , 5 × 10 13 , 7.5 × 10 13 and 1.0 × 10 14 ions/cm 2 ) of 100 MeV Au +7 beam: to be referred as 1e13, 5e13, 7.5e13 and 1e14 respectively from now onwards. Further details can be found in our earlier works 2 , 25 , 28 – 30 . To analyze irradiation induced MA, in-plane and out-of-plane SQUID measurements were performed [QD, MPMS XL-7] at 5 K. The underlying electronic and local atomic structures were then studied with x-ray absorption spectroscopy (both at near edge and far edges i.e.…”

“…We have found that SHI mediated thermal spike induced high temperatures (≈4000–6000 K) modify various metal clusters viz. FeCo 23 , 24 or Ni 25 , 26 differently. The spin-spin interaction controls the local structural parameters in these ferromagnetic nanoclusters 26 , 27 .…”

“…thermal spike in the lattice subsystem 21 – 23 . In addition, local atomic disordering 24 , change in bond length, modification of surface 25 , etc are reported consequences of SHI-matter interaction. We have found that SHI mediated thermal spike induced high temperatures (≈4000–6000 K) modify various metal clusters viz.…”