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

2016; American Institute of Physics; Volume: 6; Issue: 1 Linguagem: Inglês

10.1063/1.4941063

2158-3226

Veer Dhaka, Alexander Pyymaki Perros, Shagufta Naureen, Naeem Shahid, Hua Jiang, Joona‐Pekko Kakko, Tuomas Haggrén, Esko I. Kauppinen, Anand Srinivasan, Harri Lipsanen,

Electronic and Structural Properties of Oxides

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.