Excitation efficiency of electrons and holes in forward and reverse biasedepitaxially grown Er-doped Si diodes

In this letter, we report on the excitation efficiency of erbium ions by ho t electrons and holes in Si:Er:O and Si1-yCy:Er pn diodes at 10 K. In forwa rd bias, a higher electroluminescence efficiency at 1.54 mum is observed fo r incorporating the erbium ions in the p region of the diode, where enough holes are present to form bound excitons for erbium excitation. In reverse bias, electrons turn out to be 5000 times more efficient in impact exciting of Er3+ than holes at equal space-charge region widths. A dark region of 4 5 nm for electrons and about 70 nm for holes is present where no erbium exc itation is possible. Impact excitation of Er codoped by C is much less effi cient than for O codoping. (C) 2001 American Institute of Physics.