F. Antoni

Analytical description of the film thickness distribution obtained by the pulsed laser ablation of a monoatomic target: application to silicon and germanium

Abstract In this work, the spatial distribution of laser-generated species in vacuum from a monoatomic target is deduced from the analytical resolution of the hydrodynamic equations for a plasma expanding in the adiabatic regime. The thickness distribution of the laser deposited layers is demonstrated to be related to the initial dimensions of the plasma but independent of both the laser fluence and the atomic mass of the target element. From these calculations, we also deduced an angular distribution of the deposits as a sum of cos {ce:italic}n{/ce:italic} θ. These theoretical results are experimentally supported in the specific case of the pulsed excimer laser ablation of Si and Ge monoatomic targets.

Pulsed excimer laser deposition of Si1−xGex thin films

The ability to grow Si1−xGex thin films on single‐crystal silicon or fused silica substrates by the pulsed excimer laser ablation from a sintered SiGe target is investigated. The stoichiometry of the deposits was found to depend essentially on the Ge enrichment of the ablated target surface. Crystalline layers were obtained for substrate temperatures higher than a threshold value depending on its nature. Finally, surfaces, nearly free from droplets, were achieved by optimizing the laser irradiation conditions.

HFCVD diamond nucleation and growth on DLC carbon films obtained by laser ablation

Diamond deposition by hot filament chemical vapour deposition (HFCVD) on DLC films prepared by laser ablation (5 nm <thickness<20 nm) was studied by electron spectroscopics, including X-ray photoemission, Auger electron and electron loss spectroscopy directly connected to the HFCVD growth chamber. It is shown that, whatever the thickness and the annealing procedure, this carbon layer is removed in the gas phase or reacts with silicon to form a silicon carbide layer as soon as the typical operative conditions for diamond growth are implemented (1073 K and 0.5% CH 4 diluted in H 2 ). The instability of this carbon layer is ascribed to the etching behaviour of highly reactive hydrogen radicals at the high temperature of the diamond growth (1073 K), especially with carbon of graphitic form. Moreover, both the thickness of the carbon films and the annealing temperature greatly influence the diamond nucleation density.

Si1−xGex thin films deposited by the pulsed excimer laser ablation technique

Abstract In this paper, we investigate the possibility to use the pulsed excimer laser ablation technique for depositing Si1−xGex thin films both onto single-crystal silicon and fused quartz substrates. It is demonstrated that the film composition, surface morphology and structural properties of the deposits depend strongly on several parameters like the laser fluence and the nature as well as the temperature of the substrate during the deposition process.