Protective capping and surface passivation of III-V nanowires by atomic layer deposition

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Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2016-01-01
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Language
en
Pages
7
1-7
Series
AIP ADVANCES, Volume 6, issue 1
Abstract
Low temperature (∼200 °C) grown atomic layer deposition (ALD) films of AlN, TiN, Al2O3, GaN, and TiO2 were tested for protective capping and surface passivation of bottom-up grown III-V (GaAs and InP) nanowires (NWs), and top-down fabricated InP nanopillars. For as-grown GaAs NWs, only the AlN material passivated the GaAs surface as measured by photoluminescence (PL) at low temperatures (15K), and the best passivation was achieved with a few monolayer thick (2Å) film. For InP NWs, the best passivation (∼2x enhancement in room-temperature PL) was achieved with a capping of 2nm thick Al2O3. All other ALD capping layers resulted in a de-passivation effect and possible damage to the InP surface. Top-down fabricated InP nanopillars show similar passivation effects as InP NWs. In particular, capping with a 2 nm thick Al2O3 layer increased the carrier decay time from 251 ps (as-etched nanopillars) to about 525 ps. Tests after six months ageing reveal that the capped nanostructures retain their optical properties. Overall, capping of GaAs and InP NWs with high-k dielectrics AlN and Al2O3 provides moderate surface passivation as well as long term protection from oxidation and environmental attack.
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Dhaka , V , Perros , A , Naureen , S , Shahid , N , Jiang , H , Kakko , J-P , Haggren , T , Kauppinen , E , Srinivasan , A & Lipsanen , H 2016 , ' Protective capping and surface passivation of III-V nanowires by atomic layer deposition ' , AIP Advances , vol. 6 , no. 1 , 015016 , pp. 1-7 . https://doi.org/10.1063/1.4941063