Optimization of erbium-doped light-emitting diodes by p-type counterdoping

In this letter, we report on the influence of the space charge region width in erbium- and oxygen-doped silicon light-emitting diodes on the electroluminescence (EL) power at 1.54 μm under reverse bias conditions. The space charge region width was varied by codoping the Si:Er:O layer with boron, thereby compensating the Er–O donors. We observe a strong enhancement of the EL power with increasing width. The data indicate the existence of a dark region of approximately 45 nm in the pn junction, in which no light is generated due to a lack of hot carriers which are necessary for impact excitation of Er3+ ions.