Erbium emission in MOS light emitting devices: From energy transfer to direct impact excitation

摘要

The electroluminescence (EL) at 1.54νm of metaloxidesemiconductor (MOS) devices with Er ~(3+) ions embedded in the silicon-rich silicon oxide (SRSO) layer has been investigated under different polarization conditions and compared with that of erbium doped SiO _2 layers. EL time-resolved measurements allowed us to distinguish between two different excitation mechanisms responsible for the Er ~(3+) emission under an alternate pulsed voltage signal (APV). Energy transfer from silicon nanoclusters (Si-ncs) to Er ~(3+) is clearly observed at low-field APV excitation. We demonstrate that sequential electron and hole injection at the edges of the pulses creates excited states in Si-ncs which upon recombination transfer their energy to Er ~(3+) ions. On the contrary, direct impact excitation of Er ~(3+) by hot injected carriers starts at the FowlerNordheim injection threshold (above 5MVcm ~1) and dominates for high-field APV excitation.