Seminars Archive

Photo-induced processes at solid surfaces and interfaces: the growth of SiGe layers on Si(001) by laser epitaxy at 248 nm

Abstract
Photo-induced processes at solid surfaces and interfaces are of widespread interest for fundamental scientific questions as well as for possible technological applications in material processing. Laser stimulated chemistry and laser induced surface modification are frequently exploited for the treatment of electronics and optoelectronics materials, thin film deposition and processing, UV cleaning of surfaces, compound synthesis, material alloying, layer doping. As an example the formation of epitaxial graded SiGe alloy layers on Si(001) by pulsed UV laser irradiation of Si_xGe_(1-x)/Si(001) heterostructures will be presented. KrF excimer laser pulses at 248 nm were used to irradiate Ge and Si_xGe_(1-x) films grown on Si(100) by Chemical Vapor Deposition (CVD) or to assist the CVD growth itself. On-line single wavelength ellipsometry allowed to follow in real time the modification of the film morphology induced by the laser treatment. High resolution X-ray diffraction and Rutherford backscattering spectrometry demonstrated that the SiGe alloys exhibited excellent epitaxial quality, graded Ge profiles and partial strain relaxation. These results attest the potential of the laser assisted growth techniques for those technological applications, which require the epitaxy of high quality materials in combination with low substrate temperature, rapid processing time and eventually high spatial resolution.