Growth and modification of thin SiGeC films at low substrate temperatures through UV laser assisted processing

Enhancing the performance of solar cells, near infrared photo-detectors and microelectronic devices through band gap engineering caused an increasing attention in processes for growing thin silicon germanium carbon (SiGeC) films in a wide range of composition and crystalline structures. Moreover, the demand of using cheap substrates and the development of new devices with advanced materials like ‘‘high-k dielectrics’’ and ‘‘organic materials’’ implies the need of new processes avoiding high substrate temperatures that may decompose or alter the substrate materials, crystallise part of the heterostructures or promote segregation effects. Laser induced chemical vapour deposition (LCVD) and excimer laser assisted crystallisation (ELC) are such alternative and relatively cheap ‘‘low thermal budget’’ techniques that, in addition, are compatible with conventional IC silicon technology. The present study will show the possibility of tailoring the composition of amorphous SiGeC coatings through the adjustment of gas flow rates in LCVD processes performed at substrate temperatures between 180 and 400 8C. The modification of an amorphous film through a subsequent ELC process performed at room temperature is analysed through SEMand depth profile XPS in order to study the effects of controlled laser radiation on it, aswell as on a very thin underlaying interfacial SiO2 layer and on the Si(1 0 0) substrate. # 2004 Elsevier B.V. All rights reserved