Abstract

The thesis is divided into two topics: silicon nanocrystals based light emitting devices and erbium doped silicon nanocrystals devices. I have studied silicon nanocrystals based devices. Here I have demonstrated the role of the different injection mechanisms in determining the efficiency of the device. I have studied single and multilayer structures, both in diode or transistor configurations. Lastly, the time dependence of the electroluminescence has been studied, clarifying the role of bipolar or unipolar injection in these structures. On the second part of my thesis, I have studied Er and silicon nanocrystals co-doped devices. Firstly, the study was aimed at the understanding of the efficiency of the electrical pumping of Er ions. Then, integrated optical cavities were designed and fabricated and their optoelectronic properties measured. Here I built a specific set-up in order to measure at the same time the optical and electronic properties of active devices on wafer. Unfortunately, the measurements demonstrated that many nonlinear loss mechanisms set in when the devices are heavily injected with current. Therefore, despite the optical cavities are of high qualities, the system did not show any laser emission. On the other hand, I have demonstrated a fully integrated system where the Er doped injection device pumps a waveguide and the emission is then extracted through a grating. Last result was the experimental verification of the existence of intermediate band states through which the silicon nanocrystals to Er energy transfer occurs.