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 electrolu minescence (EL) power at 1.54 mu m under reverse bias conditions. The space charge region width was varied by codoping the Si:Er:O layer with boron, t hereby 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 gene rated due to a lack of hot carriers which are necessary for impact excitati on of Er3+ ions. (C) 1999 American Institute of Physics. [S0003-6951(99)032 31-3].