Growth and Characterization of Germanium-Based Type I Clathrate Thin Films Deposited by Pulsed Laser Ablation

Abstract

Thin films of type I clathrate material, Ba 8 Ga 16 Ge 30, have been grown using the pulsed laser ablation technique. These materials hold the potential for thermoelectric applications. Films have been deposited on a variety of substrates including silicon, quartz, sapphire, glass substrates, and YSZ cubic zirconium. Optimal crystalline films were obtained at a growth temperature of 400 o C and laser fluences at 3 J/cm 2 and above. The optimum laser fluence to produce stoichiometric films with the lowest particle density has been determined. The low ablation threshold for the UV wavelength leads to the particulate ejection during laser-target interaction. Excitation of the UV laser generated plasma by a second pulsed IR laser further reduced particulates and produced broader expansion profiles leading to large area uniform films.

Nanocolumnar Interfaces and Enhanced Magnetic Coercivity in Preferentially oriented Cobalt Ferrite Thin Films Grown Using Oblique-Angle Pulsed Laser Deposition

“…Under the above conditions, the growth rates for obliquely incident CFO thin films were measured to be 0.5 Å/s whereas those for the normal-incidence films were found to be 1 Å/s. , To optimize the growth parameters in the α-PLD process, we observed the laser-ablated plasma plumes in situ and imaged them during the film growth process. For this purpose, an intensified charge-coupled detector (ICCD) imaging system (PI Acton PI-MAX:512 UNIGEN Digital ICCD Camera System, 512 × 512 pixels, <5 ns gating capability, spectral range 150–925 nm) set at 20 μs exposure time was aligned normal to the plume propagation direction to capture the total visible emission from the laser-ablated plumes in a manner similar to our previous reports. − …”

Energy Analyses of Thermoelectric Renewable Energy Sources

“…Current TE devices operate at an efficiency of about 5% -6%. By increasing ZT by a factor of 4 predicted efficiencies can increase to 30% [5].…”

“…A related effect was discovered a little bit later in 1834 by a French scientist Jean Peltier [4,5]. Peltier found, Figure 1(b), that when he applied a current in two pieces of coupled materials, a temperature gradient can be developed and the rate of heat absorbed or released at the junctions followed a relationship of Q/dt = Π·I, where Π is Peltier coefficient and I is the applied current.…”