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

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 x 10(8) s(-1). The second method involved measuring the time response for luminescence intensity after pulsed host photoexcitation. Although some tens of mu s 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 10(7) 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. (C) 1998 American Institute of Physics. [S0021-8979(98)04120-6].