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

Abstract

Doped thin films of group‐IV semiconductors can be fabricated using the adsorption of dopant species from a liquid source to a precursor nanoparticle film, followed by laser‐sintering to incorporate and activate the dopants in the sintered thin film. A detailed study of the doping of germanium films with arsenic reveals diffusion of dopants into the film and their adsorption to the nanoparticle surface as kinetically governing steps, benefiting from the large internal surface area of the nanoparticle film. The resulting charge carrier concentration can be adjusted by the internal surface area via the nano­particle diameter, by controlling the dopant concentration in the liquid, and by the immersion time and temperature. It is shown that the method can be successfully transferred to silicon and silicon–germanium alloy films using group‐III and ‐V elements, which lead to p‐ and n‐type conductivity, respectively. Atomic dopant concentrations above 1020 cm−3 can be realized by laser‐sintering, which are electrically active to a high extent and lead to effective conductivities well above 10 S cm–1 in the mesoporous films is investigated here. The method allows flexible printing of devices using inks for the nanoparticles and the dopant and avoids toxic substances for the doping of nanoparticles in the gas phase.

Nonthermal Plasma Synthesis of Nanocrystals: Fundamental Principles, Materials, and Applications

“…In this section, we will review investigations carried out with substitutional doping of plasma-grown nanocrystals that were doped in situ. Ex situ wet chemistry doping approaches have also been proposed. , However, these do not preserve the nanocrystal’s morphology as they involve laser-assisted sintering. We will focus on the significant body of work on the doping of Si and Ge, which have received by far the most attention.…”

“…Ex situ wet chemistry doping approaches have also been proposed. 284,285 However, these do not preserve the nanocrystal's morphology as they involve laser-assisted sintering. We will focus on the significant body of work on the doping of Si and Ge, which have received by far the most attention.…”

Measurement of the in-plane thermal conductivity by steady-state infrared thermography

“…With on-sample calibration, no additional knowledge for the temperature calibration is necessary, thus the technique could be applied to novel materials such as highly porous SiGe films, as well as composite and organicinorganic hybrid materials. [30][31][32][33] The setup presented here furthermore allows to measure κ || as a function of temperature (by additionally heating the substrate in the vacuum chamber) and the application to brittle materials (due to the small hole diameters possible). While for large temperature differences generated by the optical heating losses due to thermal radiation were identified as an issue, for low temperature differences consistent results were observed.…”

Silicon‐based nanocomposites for thermoelectric application

“…Here, we summarize the properties of laser‐assisted wet‐chemically doped thin films , concentrating on the n‐type doping of Ge and Si thin films. Figure shows the room temperature conductivity and the Seebeck coefficient of thin films of the two materials as a function of the concentration of different group‐V dopants in the doping liquid.…”