Electroluminescence studies of Er and SiO co-doped Si layers prepared by molecular beam epitaxy

Er/O co-doped Si light emitting diodes (LEDs) have been fabricated using la yer structures prepared by molecular beam epitaxy (MBE). The Er/O doping wa s realized by sublimation of elemental Er and silicon monoxide simultaneous ly with Si during MBE growth. Intense Er-related electroluminescence (EL) a t 1.54 mu m was observed at room temperature from p(+)-SiGe/i-SiGe-Si/Si:Er /n(+)-Si LEDs by electron impact excitation under reverse bias. It has been found that the EL intensity was increased with increasing growth temperatu re of the Si:Er/O layer in the range of 430-575 degrees C. The electrical p umping power dependence of EL intensity has been studied. An excitation cro ss section value of similar to 1 x 10(-16) cm(2) was estimated based on the experimental data and model fitting. The EL decay behavior under various i njection and bias conditions has been studied by time-resolved EL measureme nts. The overall luminescence decay time is found to strongly depend on the injection parameters. Two types of de-excitation mechanisms due to Auger e nergy transfer to free carriers introduced by either dopant ionization or c arrier injection have been discussed. Both Auger processes play an importan t role in reduction of the EL intensity when there is a high density of car riers with excited Er ions. (C) 2000 Elsevier Science B.V. All rights reser ved.