Zemo temperatūru luminiscence AlN pulveriem

Abstract

Darbā ar ir pētīta AlN nanopulvera un makropulvera luminiscence plašā temperatūru rajonā no 8 K līdz 300 K. Tika mērīti fotoluminiscences un tās ierosmes spektri. Ir atrasts, ka abos materiālos vieni un tie paši defekti rada galvenās luminiscences joslas pie 420 nm un 480 nm, kas ir jau zināmas AlN keramikā. 420 nm luminiscenci saista ar skābekli saturošiem centriem materiāla tilpumā, bet 480 nm luminiscenci – ar līdzīgiem virsmas defektiem. Luminiscences ierosmes spektros bez jau zināmām joslām pie 250 nm un 280 nm, kas atbild par 420 nm un 480 nm luminiscenci, tika atrastas jaunas 320 nm un 340 nm joslas. Šīs ierosmes joslas mēs saistām ar luminiscences centra tiešu ierosināšanu enerģijas līmenī, no kura notiek luminiscences izstarošana. Palielinoties temperatūrai no 8 K līdz 300 K, 420 nm un 480 nm luminiscences intensitāte samazinās, ko var saistīt ar temperatūras izraisītu bezizstarojuma procesu īpatsvara palielināšanos luminiscences procesos. Iegūtie rezultāti ļauj prognozēt, ka gan AlN nanopulveris gan arī AlN makropulveris varētu būt perspektīvi materiāli jaunu redzamās gaismas avotu izveidei.

Photoluminescence of AlN nanosize powder and bulk AlN powder was investigated within a wide temperature range between 8 K and 300 K. The photoluminescence spectra and its excitation spectra were studied. It was found that in these two materials the same defect types are present responsible for two main luminescence bands at 420 nm and 480 nm known from AlN ceramics. The 420 nm band is attributed to oxygen-related defects within the material volume, whereas the 480 nm band – to the surface defects with similar structure. Two new luminescence excitation bands at 320 nm and 340 nm were found together with those well known bands at 250 nm and 280 nm responsible for the 420 nm and 480 nm luminescence, respectively. These new luminescence excitation bands could be related to direct excitation of the defect energy level responsible for emission. It was observed that the intensity of 420 nm and 480 nm luminescence decreases when temperature increases from 8 K up to 300 K. The results obtained allows proposal that both the AlN nanosize powder and bulk AlN powder are prospective materials for application in new light emitting materials useful for visible light sources.