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Top-Down Fabrication of High Quality III–V Nanostructures by Monolayer Controlled Sculpting and Simultaneous Passivation
KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.ORCID-id: 0000-0002-2069-2820
KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
2013 (Engelska)Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 23, nr 13, s. 1620-1627Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In the fabrication of IIIV semiconductor nanostructures for electronic and optoelectronic devices, techniques that are capable of removing material with monolayer precision are as important as material growth to achieve best device performances. A robust chemical treatment is demonstrated using sulfur (S)-oleylamine (OA) solution, which etches layer by layer in an inverse epitaxial fashion and simultaneously passivates the surface. The application of this process to push the limits of top-down nanofabrication is demonstrated by the realization of InP-based high optical quality nanowire arrays, with aspect ratios more than 50, and nanostructures with new topologies. The findings are relevant for other IIIV semiconductors and have potential applications in IIIV device technologies.

Ort, förlag, år, upplaga, sidor
2013. Vol. 23, nr 13, s. 1620-1627
Nyckelord [en]
semiconductor nanostructures, monolayer etching, surface passivation, nanowires, top-down fabrication, membranes
Nationell ämneskategori
Nanoteknik Annan fysik
Identifikatorer
URN: urn:nbn:se:kth:diva-104528DOI: 10.1002/adfm.201202201ISI: 000317019100003Scopus ID: 2-s2.0-84875827561OAI: oai:DiVA.org:kth-104528DiVA, id: diva2:564985
Forskningsfinansiär
Vetenskapsrådet, 349-2007-8664EU, FP7, Sjunde ramprogrammet, 248855
Anmärkning

QC 20130507

Tillgänglig från: 2012-11-05 Skapad: 2012-11-05 Senast uppdaterad: 2017-12-07Bibliografiskt granskad
Ingår i avhandling
1. Top-down Fabrication Technologies for High Quality III-V Nanostructures
Öppna denna publikation i ny flik eller fönster >>Top-down Fabrication Technologies for High Quality III-V Nanostructures
2013 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

III-V nanostructures have attracted substantial research effort due to their interesting physical properties and their applications in new generation of ultrafast and high efficiency nanoscale electronic and photonic components. The advances in nanofabrication methods including growth/synthesis have opened up new possibilities of realizing one dimensional (1D) nanostructures as building blocks of future nanoscale devices. For processing of semiconductor nanostructure devices, simplicity, cost effectiveness, and device efficiency are key factors. A number of methods are being pursued to fabricate high quality III-V nanopillar/nanowires, quantum dots and nano disks. Further, high optical quality nanostructures in these materials together with precise control of shapes, sizes and array geometries make them attractive for a wide range of optoelectronic/photonic devices.

This thesis work is focused on top-down approaches for fabrication of high optical quality nanostructures in III-V materials. Dense and uniform arrays of nanopillars are fabricated by dry etching using self-assembly of colloidal SiO2 particles for masking. The physico-chemistry of etching and the effect of etch-mask parameters are investigated to control the shape, aspect ratios and spatial coverage of the nanopillar arrays. The optimization of etch parameters and the utilization of erosion of etch masks is evaluated to obtain desired pillar shapes from cylindrical to conical. Using this fabrication method, high quality nanopillar arrays were realized in several InP-based and GaAs-based structures, including quantum wells and multilayer heterostructures. Optical properties of these pillars are investigated using different optical spectroscopic techniques. These nanopillars, single and in arrays, show excellent photoluminescence (PL) at room temperature and the measured PL line-widths are comparable to the as-grown wafer, indicating the high quality of the fabricated nanostructures. The substrate-free InP nanopillars have carrier life times similar to reference epitaxial layers, yet an another indicator of high material quality. InGaAs layer, beneath the pillars is shown to provide several useful functions. It effectively blocks the PL from the InP substrate, serves as a sacrificial layer for generation of free pillars, and as a “detector” in cathodoluminescence (CL) measurements. Diffusion lengths independently determined by time resolved photoluminescence (TRPL) and CL measurements are consistent, and carrier feeding to low bandgap InGaAs layer is evidenced by CL data. Total reflectivity measurements show that nanopillar arrays provide broadband antireflection making them good candidates for photovoltaic applications.  A novel post etch, sulfur-oleylamine (S-OA) based chemical process is developed to etch III-V materials with monolayer precision, in an inverse epitaxial manner along with simultaneous surface passivation. The process is applied to push the limits of top-down fabrication and InP-based high optical quality nanowires with aspect ratios more than 50, and nanostructures with new topologies (nanowire meshes and in-plane wires) are demonstrated.  The optimized process technique is used to fabricate nanopillars in InP-based multilayers (InP/InGaAsP/InP and InP/InGaAs/InP). Such multilayer nanopillars are not only attractive for broad-band absorption in solar cells, but are also ideal to generate high optical quality nanodisks of these materials. Finally, the utility of a soft stamping technique to transfer free nanopillars/wires and nanodisks onto Si substrate is demonstrated. These nanostructures transferred onto Si with controlled densities, from low to high, could provide a new route for material integration on Si.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2013. s. xvi, 75
Nyckelord
III-V nanostructures, colloidal lithography, top-down fabrication, dry etching, quantum well, multilayer structures, nanowires, nanopillars, nanodisks, mono-layer etching, surface passivation, photoluminescence, carrier life time, total reflectivity, photonic crystals, nanomesh
Nationell ämneskategori
Fysik Nanoteknik
Identifikatorer
urn:nbn:se:kth:diva-117766 (URN)978-91-7501-633-7 (ISBN)
Disputation
2013-02-25, Sal/Hall C1, KTH-ICT, Electrum, Isafjordsgatan 26, Kista, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20130205

Tillgänglig från: 2013-02-05 Skapad: 2013-02-04 Senast uppdaterad: 2013-11-11Bibliografiskt granskad

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