Enhancement of the photoluminescence in Er-doped Al2O3 fabricated by atomic layer deposition

We show the enhancement of the photoluminescence at λ = 1:5 μm in highly-doped (> 10 21 cm -3 ) Er-Al 2 O 3 samples by controlling the vertical distance between the Er-ions using atomic layer deposition (ALD) technique. Er 2 O 3 and Al 2 O 3 were deposited on top of silicon in an alternating fashion with ALD. Five Er 2 O 3 -Al 2 O 3 samples were fabricated by keeping the amount of Er 2 O 3 constant but changing the thickness of the Al 2 O 3 -layers between the Er 2 O 3 -layers. The PL spectra of the samples reveal that the PL signal enhances up to 90% when the vertical distance (the number of Al 2 O 3 -layers) between the Er-ions increases. The PL enhancement can be related to the reduction of up-conversion signal at 532 and 650 nm in the Er-ions. Our results demonstrate that ALD is an excellent technique to fabricate and to optimize Er-doped materials due to its unique depositions properties.