Evaluation of the energy-transfer rate between an Er 4f shell and a Si host in Er-doped Si

Abstract

We estimated the energy-transfer rate between an erbium (Er) 4f shell and a Si host by using two independent measurements. The first method involved measuring the temperature dependence of the decay time of Er 4f-shell luminescence and obtaining the energy-transfer rate by assuming that the energy transfer is assisted by nonradiative multiphonon processes and that thermal quenching is due to an energy back-transfer mechanism. The estimated value was 2×108 s−1. The second method involved measuring the time response for luminescence intensity after pulsed host photoexcitation. Although some tens of μs luminescence delay after host excitation has been reported, we found that the slow response time of the detection system may cause spurious delay. We measured the luminescence decay curve using a system with a fast response time and analyzed the data, taking into account the system response time. The energy transfer rate was estimated to be at least 107 s−1. This estimation is consistent with the result obtained by the first method, mentioned above, confirming a rather large energy-transfer rate between the Er 4f shell and Si host.