Auger quenching-based modulation of electroluminescence from ion-implanted siliconnanocrystals

Abstract

We describe high-speed control of light from silicon nanocrystals underelectrical excitation. The nanocrystals are fabricated by the ion implantation ofSi+ in the 15 nm thick gate oxide of a field effect transistor at 6.5 keV. A characteristic read-peakedelectroluminescence is obtained either by DC or AC gate excitation. However, AC gateexcitation is found to have a frequency response that is limited by the radiative lifetimes ofsilicon nanocrystals, which makes impossible the direct modulation of light beyond100 kb s−1 rates. As a solution, we demonstrate that combined DC gate excitationalong with an AC channel hot electron injection of electrons into thenanocrystals may be used to obtain a 100% deep modulation at rates of200 Mb s−1 and low modulating voltages. This approach may find applications in biological sensingintegrated into CMOS, single-photon emitters or direct encoding of informationinto light from Si-nc doped with erbium systems, which exhibit net optical gain.In this respect, the main advantage compared to conventional electro-opticalmodulators based on plasma dispersion effects is the low power consumption(104 timessmaller) and thus the inherent large scale of integration. A detailed electrical characterization is also given. AnSi/SiO2 barrierchange from Φb = 3.2 to 4.2 eV is found while the injection mechanism is changed from Fowler–Nordheim tochannel hot electron, which is a clear signature of nanocrystal charging and subsequentelectroluminescence quenching.