Optical And Electrical Characteristics Of Leds Fabricated From Si-Nanocrystals Embedded In Sio2

Structures containing Si nanocrystals embedded in SiO2 are candidates for optoelectronic and photonic applications due to their intense visible emission at room temperature, high thermal and chemical stability and compatibility with CMOS technology. Extensive investigations have demonstrated strong tunable photo- and electroluminescence (PL, EL), and even optical amplification [1]. The photon absorption in such systems is a fundamental transition modulated by quantum confinement effects and takes place in the core of the nanocrystal, while the PL consists of an intense and wide emission peaking in the near infrared or visible spectrum [7]. The Si-SiO2 interface plays a dominant role in the emission mechanism. This is possible either through the existence of surface radiative states[8] or because of vibronic interactions among electron-hole pairs created in the nanocrystals and the polarizable material surrounding them [9]. The suppression of non-radiative defects at the Si-SiO2 interface is a process required in order to increase the radiative yield without affecting the emission mechanism. It has been reported that an increase in radiative efficiency is possible by a suitable thermal treatment in hydrogen atmosphere [11]. However, the microscopic nature of the H-passivated defects was not fully understood. This research topic has been addressed by us extensively in recent papers [13].