Improving the photoluminescence of thin films by nanostructuring the rare-earth ion distribution

Enhanced photoluminescence of nanostructured Er3+-doped a-Si/a-Al2O3 thin films prepared by PLD

“…A slower decay, which can be associated to the emission by the erbium ions is then observed, and can be fitted by a single exponential function with a 5.7 ms lifetime. This value is higher than the one measured for the film with no a-Si layers, whose decay could be fitted by a single exponential function with a 2.2 ms lifetime, in agreement with the values reported for similar films [9]. It has been reported that the local density of optical states (LDOS) close to the interface of dielectric media depends on their refractive indices [20,21] and their spatial confinement [22].…”

“…In order to synthesize an Er 3+ -doped a-Si/a-Al 2 O 3 film having the structure detailed in Section 2.1, the number of pulses on each target has been designed for depositing two 50 nm-thick Al 2 O 3 buffer layers and two 5 nmthick amorphous silicon layers. The Al 2 O 3 layer between the a-Si layers has been doped following the procedure described in detail elsewhere [8,9] in order to achieve a periodic array of 50 Er 3+ -doped layers separated by 5 nm thick a-Al 2 O 3 layers. This doping structure has been shown to efficiently minimize clustering and concentration quenching effects [8,9].…”

“…The Al 2 O 3 layer between the a-Si layers has been doped following the procedure described in detail elsewhere [8,9] in order to achieve a periodic array of 50 Er 3+ -doped layers separated by 5 nm thick a-Al 2 O 3 layers. This doping structure has been shown to efficiently minimize clustering and concentration quenching effects [8,9]. The first and the last Er 3+ -doped layers are designed to be separated from the a-Si layers by 8 nm thick a-Al 2 O 3 layers.…”

“…It has been shown in the case of amorphous aluminium oxide (a-Al 2 O 3 ) that the luminescence emission of Er 3+ ions can be optimized by preparing doping structures in which the Er 3+ ions are distributed in well defined layers for which the Er concentration and the indepth layer separation are controlled at the nanoscale [8,9]. In this way Er clustering and luminescence by quenching due to Er-Er interaction are minimized.…”

“…Among all the techniques allowing the elaboration of thin films, pulsed laser deposition (PLD) is a powerful and versatile tool for the synthesis of thin films with tailored composition and nanostructure; it allows especially to fabricate at room temperature good quality oxide films (exhibiting a low porosity and low losses [6,7]) containing rare earth ions whose distribution within the matrix can be accurately controlled [8,9]. It has been shown in the case of amorphous aluminium oxide (a-Al 2 O 3 ) that the luminescence emission of Er 3+ ions can be optimized by preparing doping structures in which the Er 3+ ions are distributed in well defined layers for which the Er concentration and the indepth layer separation are controlled at the nanoscale [8,9].…”