Laser-sintered thin films of doped SiGe nanoparticles

Abstract

We present a study of the morphology and the thermoelectric properties of short-pulse laser-sintered (LS) nanoparticle (NP) thin films, consisting of SiGe alloy NPs or composites of Si and Ge NPs. Laser-sintering of spin-coated NP films in vacuum results in a macroporous percolating network with a typical thickness of 300 nm. The Seebeck coefficient is independent of the sintering process and typical for degenerate doping. The electrical conductivity of LS films rises with increasing temperature, best described by a power-law and influenced by two-dimensional percolation effects.Comment: 4 pages, 4 figure

Thermal conductivity of mesoporous films measured by Raman spectroscopy

“…2 Lasersintered films of silicon-germanium nanoparticles (NPs) are such a candidate. 3 Alloy scattering on the atomic scale, inclusions of pristine NPs with diameters of 20-50 nm in larger grains of a typical size of 100-150 nm and a mesoscale porosity of a characteristic length scale of 300-500 nm provide the desired scattering centers for phonons of different wavelengths in this material system. However, the determination of j for this material by established standard methods is difficult.…”

“…A more detailed description of the film fabrication can be found in Ref. 3. The NPs used consisted of undoped Ge (27 nm diameter) and Si 78 Ge 22 (23 nm diameter), synthesized with approximately 2% P as a dopant.…”

“…3 A typical electrical conductivity of samples prepared similarly to this work and comprising a composition of Si 80 Ge 20 with 1% P-doping is r % 15 S=cm at T % 500 K. 3 This value has not been normalized by porosity, so that we relate it to j eff . Compared to bulk-nanostructured samples made from the same NP batches using current-assisted pressure-assisted sintering, 26 the ratio r=j is approximately twice as high for the laser-sintered films.…”

Laser‐Assisted Wet‐Chemical Doping of Sintered Si and Ge Nanoparticle Films

“…Figure 1 illustrates these fabrication steps. [ 13,18,21 ] Panel (f) schematically shows that dopants in the solid thin fi lm can either occupy dilute substitutional lattice sites and be electrically active, or remain electrically inactive due to clustering [ 22,23 ] or occupation of surface states. [ 18 ] In the side-view sketch in panel (b), the NP fi lm is immersed in the doping liquid.…”

Improved thermoelectric property of B-doped Si/Ge multilayered quantum dot films prepared by RF magnetron sputtering

“…Moreover, great achievements have been realized for other thin films, such as self-assembled Si 1−x Ge x quantum dots, which can significantly reduce thermal conductivity leading to the improvement of the thermoelectric ZT, and quantum dots embedded in a multistacked layer structure can also greatly reduce the thermal conductivity. [20][21][22] Although MOCVD and PECVD are excellent for preparing superlattice and=or quantum dot nanostructures, small sample size and high cost hinder their further applications. On the other hand, magnetron sputtering can potentially reduce the cost, enable large-scale production, and enhance the properties of Si=Ge-based thermoelectric films.…”