Electron and hole impact excitation of Er in MBE grown Si:O and Si1−yCy diodes

We have investigated the doping and electroluminescence (EL) properties at 1.54 μm of erbium ions in Si:O and Si1−yCy:Er layers completely grown by MBE. Erbium in Si1−yCy:Er films shows a lower doping density (p=+1.6×1017 cm−3) than erbium in Si:O (n=−3×1018 cm−3). The energy levels responsible for doping and optical erbium activation are different because different activation energies are observed. To realise both maximum luminescence output and low doping concentration, it is important to incorporate the carbon on substitutional lattice sites. The efficiency for electron and hole excitation by impact processes is compared. Electrons are about 5000× more efficient for impact excitation of Er3+ than holes.