Abstract EN:

This work reports on the characterization of Si1-xGex/Si heterostructures grown on Si by rapid thermal chemical vapour deposition (RT-CVD). The goal of this study, was to contribute to a better understanding of the electronical properties of this strained system, and to analyse the quality of this material for its application to heterojunction bi polar transistors (HBTs). A detailed study, of the photoluminescence (PL) properties of Sit-xGex strained layers is presented. The excitonic transitions, observed for the first time in thick Si Ge strained layers, have been used to give the band gap variations as a function of germanium content, at low temperatures. The effects of band gap narrowing (BGN) du to heavy boron doping have been also studied by PL rneasurements on Sio,s2Geo,18 strained films. The relaxation process bas been studied by rneans of PL rneasurements, and electrical characterizations (I(V), C(V), deep level transient spectroscopy (DLTS)), in order to know accurately the limits of stability of the strained layers. Deep levels correlated to the relaxation defects have been detected by spacialy resolved DLTS measurements. This procedure allows us to observe separately, the levels associated to the interfacial misfit dislocations, and the dislocations within the SiGe layers. Finally, this study leads us to conclude on the excellent quality of the RT-CVD heteroepitaxial Iayers, and hence, on the ability to use this strained system for the realisation of advanced Si-based devices.