1. LaB₆ nanostrutures for field emission

LaB₆ films have been deposited on verity of substrates such as tungsten and Rhenium flats and pointed tips by pulsed laser deposition technique. The field emission studies on have been performed in the conventional field emission geometry. In case of LaB₆/tungsten tip, the Fowler-Nordheim plot obtained from the current-voltage characteristic was found to be linear in accordance with the quantum mechanical tunneling phenomenon. A current density of 1.2×10⁴ A/cm² was drawn from the deposited tip. The field enhancement factor was calculated to be 5537cm⁻¹, indicating that the field emission was from nanoscale protrusions present on emitter surface. The emission current-time plots showed very good stability of the emitter.

References: 

1. D. J. Late et al., Enhanced Field Emission of Pulsed Laser Deposited nanocrystalline ZnO thin films on Re and W, Appl. Phy. - A, 95, 2009, 613–620.
2. D. J. Late et al., Enhanced field emission from LaB₆ thin films with nano-protrusions grown by pulsed laser deposition on Zr foil, Appl. Surf. Sc. 254(11), 2008, 3601-3605.
3. D. J. Late et al., Some aspects of pulsed laser deposited nanocrystalline LaB₆ film: Atomic force microscopy, constant force current imaging and field emission investigations, Nanotechnology, 19, 2008, 265605.
4. D. J. Late et al., Field Emission from Nanocrystalline LaB₆ prepared by Laser Ablation, Ultramicroscopy 107, 2007, 825.
5. D. J. Late et al., Field Emission Studies on Well Adhered Pulsed Laser Deposited LaB₆ Film on W Tip, Appl. Phys. Lett. 89, 2006, 123510: 1 - 3. 

2. CMR materials

Epitaxial thin films of Colossal Magneto-resistance (CMR) material La_0.5Pr_0.2Ba_0.3MnO₃ were deposited on LaAlO₃ single-crystal substrates using pulsed laser deposition (PLD) technique with different growth parameters. Structural, surface morphological, electrical, and magnetotransport measurements on these films revealed that unoptimized growth parameters during the deposition using the third harmonic of a Q-switched Nd: YAG laser yielded structurally inhomogeneous epitaxial films having a columnar morphology, while the optimized growth parameters using an excimer laser during the PLD resulted in homogeneous epitaxial films with a smooth morphology. Interestingly, at a temperature of 5 K, the films with unoptimized growth parameters showed a large high-field magnetoresistance (MR) of ~90% while the films with optimized growth parameters showed a high-field MR of only ~15%. It is contemplated that this exceptionally large MR in the un-optimized films might be due to the phase separation and coexistence of metallic and insulating phases. 

References: 

1. K. R. Mavani et al., Growth Parameters Dependent Magnetoresistance in Pulsed Laser Deposited (La_0.5Pr_0.2)Sr_0.3MnO₃ Thin Films, J. Appl. Phys. 98, 2005, 86111:1-3.
2. J. H. Markna et al., Enhancement of electronic transport and magneto-resistance of Al₂O₃ impregnated (La_0.5Pr_0.2)Sr_0.3MnO₃ thin films, Europhysics Lett., 79, 2007, 17005: 1-5.
3. J. H. Markna et al., Nano-Engineering by Implanting Al₂O₃ Nano Particle as Sandwiched Scattering Centers in Between the La_0.5Pr_0.2Sr_0.3MnO₃ Thin Film Layers, J. Nanoscience and Nanotechnology, 9(9), 2009, 5687-5691.
4. N. Kumar et. al., Room temperature magnetoresistance in Sr₂FeMoO₆/SrTiO₃/ Sr₂FeMoO₆ trilayer devices, P. Misra, RK Kotnala, A Gaur, RS Katiyar, J. Phys. D: Appl. Phys. 47(6), 2014, 065006.
5. Nitu Kumar et al., Fabrication of Sr₂FeMoO₆ try-layer structure for magnetoresistive applications, Integr. Ferroelectr., 157(1), 2014, 89-94. 

3. Si Nanoparticles 

We have grown particulate free multilayer structure of Al₂O₃ capped Si quantum dots of different mean sizes ranging from 1 nm to 3 nm as confirmed by TEM analysis by using a off-axis pulsed laser deposition scheme. A monotonic blueshift in the band-gap of Si nanoparticles with decreasing particle size as observed in photoabsorption spectra of Si  nanoparticles was in line with the putative quantum confinement effects. Room temperature photoluminescence from Si quantum dots grown for different times showed features without any apparent size dependent spectral shift which, albeit has earlier been explained by others originating from the defect levels at the interface of Si and SiO₂ shells surrounding the nanoparticles but still have certain mysteries attached.

Reference:  A. P. Detty et al., Studies on ensembles of luminescent silicon nanoparticles embbedd in silicon nitride grown by pulsed laser deposition, J. Nanosci. Lett., 1-6, 2013.

4. Laser Induced Oxidation of Si surface to grow of ultra-thin SiO₂

Downscaling of device dimensions is essential for the development of new generation ultra large scale integrated (ULSI) circuits based on complementary metal oxide semiconductor field effect transistors (CMOSFET). However, because of continuous downscaling, the thickness of SiO₂ gate dielectric has already reduced to a few mono-layers. Further thinning of SiO₂ poses several challenges, including control of growth and uniformity of ultra-thin SiO₂^. We have very recently reported a novel technique based on pulsed laser heating to grow ultra-thin SiO2 with thickness less than 4 nm on the surface of Si substrate kept at room temperature. Third harmonic laser pulse of a Q-switched Nd:YAG laser (355 nm) with a repetition rate of 10 Hz and pulse width of 6 ns was used to heat the silicon wafer in O₂ ambient pressure to grow SiO₂ in a very controlled manner. The laser fluence on the substrate was maintained at ~ 75 mJ/cm². SiO₂ was grown for different durations in the range of 30 to 180 sec in an oxygen pressure of ~ 10^-2 Torr.  The leakage current density against applied gate voltage (J–V) characteristics of the MOS devices using controlled pulsed laser  heating revealed  the low leakage current density and the breakdown field strength  >10 MV/cm, signifying the excellent quality of the laser induced oxide.