GaAs/AlGaAs Core Multishell Nanowire-Based Light-Emitting Diodes on Si

Tomioka, Katsuhiro; Motohisa, Junichi; Hara, Shinjiro; Hiruma, Kenji; Fukui, Takashi

doi:10.1021/nl9041774

Cited by 330 publications

(319 citation statements)

References 47 publications

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“…This finding has important implications for NW-based devices that require a high radiative recombination intensity and/or long radiative lifetime, e.g. LEDs [191][192][193], lasers [194,195] and solar cells [29,32,134].…”

Section: Discussionmentioning

confidence: 99%

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

et al. 2014

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This thesis deals with the growth of GaAs nanowires (NWs) by molecular beam epitaxy (MBE) using vapor-liquid-solid method on various substrates including GaAs(111)B, Si(111) and graphene. The growth of the NWs on GaAs substrates was carried out by Au-catalyzed technique, whereas the growths on Si and graphene substrates were carried out using self-catalyzed technique that has been the main focus of this thesis. The long-term goal of this work was to produce p-n radial junction GaAs NWs for solar cell applications.Necessary conditions were established for obtaining vertical self-catalyzed GaAs NWs on Si(111), which is reproducible from run-to-run. One of the major issues in these NWs grown by both Au-and self-catalyzed techniques is their crystal structure. The Au-catalyzed GaAs NWs usually adopt a wurtzite (WZ) crystal phase, whereas the self-catalyzed NWs a zinc blende (ZB) phase. However, in both the cases the NWs contain stacking faults, rotational twins or/and a mixed crystal phase. The ZB and WZ phases show different optical properties, and one phase might be favored over other for certain applications. Therefore the crystal phase was controlled within single NWs by tuning the V/III ratio and introducing GaAsSb inserts. The change of the crystal phases was correlated with the change in the contact angle of the Ga droplet.Since the discovery of graphene, an ultra-thin two-dimensional material, the research on graphene has become an active field in recent years due to its remarkable properties including excellent electrical and thermal conductivities, mechanical strength and flexibility, and optical transparency. By growing the semiconductor NWs on graphene, a completely new hybrid system can be envisioned where the unique properties of both NWs and graphene can be utilized. Therefore we established a method for the growth of semiconductor NWs on graphene by demonstrating epitaxial growth of vertical GaAs and InAs NWs on different graphitic substrates.Core-shell heterostructure, doping, optical properties, and position controlled growth of self-catalyzed GaAs NWs were investigated. Growth of GaAs/GaAsSb coreshell NWs where the Sb content was tuned from about 10% -70% was studied. The effect of growth temperature and the Sb flux on the morphology of GaAsSb shell was investigated. In addition, by utilizing the core-shell geometry where the shell copies the crystal phase of the core, WZ phase of GaAsSb was demonstrated. Successful p-type doping of GaAs core using Be as dopant, and n-type doping of GaAs shell using Si and Te as dopants were achieved. To investigate the optical properties, GaAs/AlGaAs coreshell NWs were grown with different V/III ratios during the core growth. The NWs grown with high V/III ratio, despite containing a higher density of twinned ZB and WZ GaAs with SFs, were found to have superior optical quality as compared to the NWs grown with low V/III ratio that contain pure ZB GaAs. The observed V/III ratio dependent optical quality was correlated to the intrinsic defects such as As vac...

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Section: Discussionmentioning

confidence: 99%

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

et al. 2014

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“…Semiconductor nanowires (NWs) have attracted considerable interest in recent years because of their potential applications in devices such as field-effect transistors [1,2], light-emitting diodes [3][4][5][6], and solar cells [7,8]. The most-surprising feature of nanowires is that they can be grown with a wurtzite (WZ) crystal structure by appropriately adjusting the growth conditions such as growth temperature, V/III ratio, and doping amount [9][10][11][12][13][14][15][16], even though they are stable in the zinc blende (ZB) phase of the bulk crystal.…”

Section: Introductionmentioning

confidence: 99%

“…We have grown III-V compound semiconductor nanowires by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE) [1,4,[8][9][10][11][22][23][24][25][26]. The crystal structures of InP nanowires can be controlled by adjusting the growth conditions of SA-MOVPE, and pure WZ InP nanowires can be obtained at high growth temperature and low V/III ratio [9,10].…”

Section: Introductionmentioning

confidence: 99%

Growth of wurtzite GaP in InP/GaP core–shell nanowires by selective-area MOVPE

Ishizaka

Hiraya

Tomioka

et al. 2015

Journal of Crystal Growth

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A GaP nanowire is promising from the viewpoint of device applications because when its crystal phase is changed from zinc blende (ZB) to wurtzite (WZ), its band gap changes from indirect to direct. GaP in the WZ phase is theoretically and experimentally shown to have the possibility of "green" emission. Here we report on the growth of WZ GaP in InP/GaP core-shell nanowires by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE). WZ InP nanowires were used as a template for transferring the WZ structure to GaP. Transmission electron microscopy revealed that WZ GaP was grown on the sidewalls of the InP core in the lateral <-211> direction and that ZB GaP was grown on the top of the InP core in the axial <111>A direction. A growth model for the different crystal structures of the GaP shell is proposed from the viewpoint of the growth direction. The WZ structure is "transferred" from the InP core to the GaP shell only when GaP grows in the direction perpendicular to the WZ stacking direction of the InP core. This so-called "crystal structure transfer" can also be applied to p-and n-doped GaP and is therefore promising for fabricating WZ-GaP-based light-emitting diodes.

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“…11,12) In this study, we report the growth and characterization of WZ InP/AlGaP CMS NWs with QW structures for the green color spectrum. The WZ AlGaP at an Al composition of around 20% is expected to have the band gap energy in the green spectral region according to calculations of their band structures.…”

mentioning

confidence: 99%

Growth and characterization of wurtzite InP/AlGaP core–multishell nanowires with AlGaP quantum well structures

Ishizaka

Hiraya

Tomioka

et al. 2016

Jpn. J. Appl. Phys.

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We report on selective-area growth and characterization of wurtzite (WZ) InP/AlGaP core-multishell nanowires. Quantum well (QW) structures were fabricated in the AlGaP multishells by changing alloy compositions. Transmission electron microscopy revealed that the AlGaP multishell was grown with a WZ structure on side of the WZ InP core. The lattice constants of the WZ InP core and WZ AlGaP shell were determined by X-ray diffraction. Cathodoluminescence studies showed that the WZ AlGaP QW with an Al composition of 20% had green emissions at 2.37 eV. These results open the possibility for green light-emitting diodes using WZ AlGaP based materials. 2Color mixed RGB light-emitting diodes (LEDs) are promising candidates for future solidstate lightning and display technology due to their potential advantages in energy conversion efficiency and color rendering index (CRI). 1,2) However, achieving high efficient LEDs in the green region is challenging due to a lack of suitable semiconductor materials, which is known as the "green gap". 3,4) Non-nitride III-V materials having wurtzite (WZ) structures have recently offered a new approach to overcome this issue. Some theories predict that GaP and AlP in the WZ structures have direct band gaps in contrast to the conventional zinc blende (ZB) structures with indirect band gaps. [5][6][7] Although this approach has been experimentally demonstrated in WZ GaP 8,9) and WZ AlInP, 10) these WZ materials with quantum well (QW) structures required for LED applications have not been reported so far.In nanowire (NW) structures, radial core-multishell (CMS) NWs with QW structures are suitable structures for LED applications. 11,12) In this study, we report the growth and characterization of WZ InP/AlGaP CMS NWs with QW structures for the green color spectrum. The WZ AlGaP at an Al composition of around 20% is expected to have the band gap energy in the green spectral region according to calculations of their band structures. 6,7) The CMS NWs were synthesized by selective-area metal organic vapor phase epitaxy (SA-MOVPE). In SA-MOVPE, InP NWs can be grown with a pure WZ structure by properly adjusting the growth conditions. 13-15) Based on these WZ InP NWs, the crystal structure transfer method [16][17][18] was applied for the radial multishell growth. At first, a 20-nm-thick SiO 2 layer was deposited on an InP (111)A substrate using plasma sputtering, and the SiO 2 layer was partially removed using electron-beam (EB) lithography and wet chemical etching. The SiO 2 patterns were designed to be a periodic array of openings with a diameter of 130 nm.The SA-MOVPE was performed in a low-pressure MOVPE reactor using trimethylaluminum (TMAl), trimethylgallium (TMGa), trimethylindium (TMIn), and tertiarybutylphosphine 3 (TBP) as source materials. Prior to the growth, the native oxide on the openings was removed using thermal cleaning for 5 min at 600°C under a hydrogen and TBP ambient. After thermal cleaning, WZ InP NWs were grown for 15 min at 660°C with a V/III ratio of 18, which is t...

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GaAs/AlGaAs Core Multishell Nanowire-Based Light-Emitting Diodes on Si

Cited by 330 publications

References 47 publications

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

Growth of wurtzite GaP in InP/GaP core–shell nanowires by selective-area MOVPE

Growth and characterization of wurtzite InP/AlGaP core–multishell nanowires with AlGaP quantum well structures

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