Er-related trap levels in GaAs:Er,O studied by optical spectroscopy under hydrostatic pressure

An optical spectroscopic study of Er-related luminescence in GaAs:Er,O as a function of temperature and applied hydrostatic pressure is reported. We observed the appearance of different Er-related luminescence under the application of hydrostatic pressure. The temperature dependence of the luminescence intensities for three kinds of Er centers as a function of pressure is measured and discussed in terms of the trap levels formed by the Er centers. It is shown that the energy-transfer process between photoexcited carriers in the host and the $4f$ shell of the ${\mathrm{Er}}^{3+}$ ion may occur when trap levels associated with an Er center enter the band gap under the application of hydrostatic pressure.