Croissance de boîtes quantiques In(Ga)As sur substrats de silicium et de SOI pour la réalisation d'émetteurs de lumière
This thesis focuses on the study of the self-organized growth of In(Ga)As quantum dots (QDs) on a silicon substrate. The purpose of this work is to pave the way for a monolithic integration of III-V semiconductor-based light emitter on silicon. One of the big challenges of this project is to overcome the high lattice mismatch between InGaAs and Si which can induce structural defects in the QDs. Another key challenge comes from the expected type II In(Ga)As/Si interface that is detrimental for efficient light emission. In order to solve the "interface type" issue, we suggested to insert the In(Ga)As QD plane inside a thin silicon layer grown on a SOI substrate. Confinement effects of the Si/SiO2 quantum well are expected to raise the X-valley of the Si conduction band above the Γ-valley, leading to a type I interface in both direct and reciprocal space. The influence of different parameters (such as the amount of deposited In(Ga)As, the growth temperature, the V/III ratio and the gallium content...) on the growth mode and on the structural and optical properties of the In(Ga)As QDs grown on Si(001) are experimentally studied. We propose an interpretation of the microscopic phenomena governing the formation of the QDs as a function of gallium content. We finally show the possibility of making In0,4Ga0,6As QDs on Si(001) substrates, these QDs being free of 'plastic relaxation'-related structural defects. The expected luminescence from the QDs was not obtained probably due to two incompatible conditions: the first, required for growing high structural quality QDs (possible only for In(Ga)As containing less than 50% of In) and the second, essential for maintaining a type I interface band alignment (theoretically possible for an In content greater than 50%). This work is contributing to the understanding of In(Ga)As QDs growth on Si(001) substrates and to the know-how of capping such QDs with silicon inside a III-V molecular beam epitaxy reactor.