Design and manufacture of quantum-confined punch-through SOI light sources

Abstract

To investigate quantum-confinement (QC) effects on silicon (Si) light source electroluminescence (EL) properties like external power efficiency (EPE) and spectral emission, nanometer-scale Si finger junctions were manufactured in a fully customized silicon-on-insulator (SOI) production technology. All spectrometer-measured thickness-confined SOI light sources displayed pronounced optical power for 600 nm < λ < 1 μm. The best thickness-confined SOI light source emitted about 24 times more optical power around λ = 844 nm and exhibited an EPE improvement factor of about 21 compared to a 350 nm bulk-CMOS avalanche reference light-source operating at the same current. Internal quantum efficiency (IQE) enhancements factors of about 3.5 were attributed to carrier-confinement. The punch-through (PT) technique, which introduced breakdown voltages as low as 6 V, increased the SOI light source EPE by about a factor 2.5. It was estimated that geometric-optical improvement techniques that include Si finger surface profiling, raised the SOI light source external quantum efficiency (EQE) by about a factor 1.7. It was further shown that the SOI Si handle could be used to reflect up to about 40 % of light that would otherwise be lost due to downward radiation back up, thereby increasing the EPE of SOI light sources.