Hexagonal ferromagnetic MnAs nanocluster formation on GaInAs∕InP (111)B layers by metal-organic vapor phase epitaxy

Abstract

The authors report the self-assembly of hexagonal MnAs nanoclusters on GaInAs ͑111͒B surfaces by metal-organic vapor phase epitaxy. The ferromagnetic behavior of the nanoclusters dominates the magnetic response of the samples when magnetic fields are applied in a direction parallel to the wafer plane. For the magnetic fields applied in a direction perpendicular to the plane, diamagnetic characteristics are dominant. The results indicate that the c axis of the nanoclusters is perpendicular to the plane, and that their a axis is in plane. They are consistent with the results of crystallographic analysis, where the nanoclusters' c axis is shown to be along a GaInAs ͓−1−1−1͔ direction. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2349309͔Ferromagnetic materials hybridized in III-V compound semiconductors ͑FM III-V hybrids͒ and III-V compoundbased diluted magnetic semiconductors ͑III-V DMSs͒ are promising for the realization of nanospintronic devices using not only the charge but the spin of carriers. In MnAs/ GaAs, GaMnAs, and InMnAs materials systems where extensive research efforts have been carried out, magnetic thin films have been grown on GaAs layers by molecular beam epitaxy at an extremely low growth temperature ͑LT-MBE͒, 1-3 implantation of magnetic ions into semiconductors, 4 and metalorganic vapor phase epitaxy ͑MOVPE͒. 5,6 We have pursued FM III-V hybrids, in particular, using MnAs nanoclusters ͑NCs͒ embedded in GaInAs/ InP ͑001͒ layers grown by MOVPE. 7,8 InP-related materials are more suitable for the fabrication of key devices in optical communication systems for 1.3 and 1.55 m wavelength bands. Recently, LT-MBE of III-V DMS, e.g., GaInMnAs, on InP ͑001͒ wafers has been reported, 9,10 and waveguide-type optical isolators using the magneto-optical effects of MnAs NCs have been proposed. 11 Ferromagnetic MnAs thin films, in addition, serve as an electrical spin injection source into semiconductors. 12 For the growth of hexagonal NiAs-type MnAs layers, ͕111͖ orientations of zinc-blende ͑ZB͒-type materials are promising because of the similarity of the crystallographic structures. MnAs "thin films" have been grown not only on GaAs ͑111͒B ͑Refs. 13-18͒ but on Si ͑111͒ ͑Ref. 19͒ surfaces by LT-MBE. Another potential advantage using the ͕111͖ orientations is the catalyst-free formation of onedimensional ͑1D͒ semiconductor nanowires ͑NWs͒ using selective-area MOVPE as promising building blocks for future nanophotonics and electronics. 20,21 The hybridization of ferromagnetic NCs into 1D semiconductor NWs possibly leads to the understanding of physical properties in 1D spinpolarized electronic systems and the realization of 1D nanospintronic devices in the next generation. We believe that the MOVPE techniques in the present work are one of the most powerful methods to meet this future goal. In this letter, we demonstrate the self-assembly of ferromagnetic MnAs NCs on planar GaInAs ͑111͒B surfaces by MOVPE. This letter describes the results of fundamental crystallographic and magnetic characterizations...

Magnetic domain characterizations of anisotropic-shaped MnAs nanoclusters position-controlled by selective-area metal-organic vapor phase epitaxy

“…[2][3][4][5]9 We have demonstrated the epitaxy of ferromagnetic NiAstype MnAs nanoclusters ͑NCs͒ self-assembled on GaInAs/ InP ͑111͒B wafers by metal-organic vapor phase epitaxy ͑MOVPE͒. 10,11 For the NiAs-type ͑or ZB-type͒ MnAs growth, the ͕111͖ orientations of ZB-type layers are promising because of the similarity of their crystal structures. Another potential advantage in using the ͕111͖ orientations is the catalyst-free "buildup" fabrication of one-dimensional ͑1D͒ semiconductor nanowires ͑NWs͒ and ferromagnet/ semiconductor heterostructured NCs position-controlled on semiconductor wafers by selective area MOVPE ͑SA-MOVPE͒ because atomically flat crystal facets and abrupt heterointerfaces are formed without any process-induced damage and contaminations.…”

“…͑CH 3 ͒ 3 Ga, ͑CH 3 ͒ 3 Al, ͑CH 3 C 5 H 4 ͒ 2 Mn and 20%-AsH 3 diluted in H 2 were used as source materials for SA-MOVPE. 17 The growth temperature, T g , and the V/Mn ratio, whose definition was given elsewhere, 10 were 800-850°C and 375-1125, respectively. MnAs NCs were formed directly on partially SiO 2 -masked GaAs ͑111͒B wafers ͑Figs.…”

Effect of the cluster magnetization on the magnetotransport at low temperatures in ordered arrays of MnAs nanoclusters on (111)BGaAs

“…An orientation of the magnetization in the cluster plane was also found by Hara et al, who performed angle-dependent measurements of the magnetization for randomly distributed nanoclusters on (111)B GaInAs/InP surfaces. 22 For all three arrangements FMR measurements in in-plane geometry were also performed. The results are shown in Fig.…”

Proceedings of the 4th International Workshop on Computational Terminology (Computerm)

“…So far, we were able to complete five fully annotated papers, which can allow us to start our preliminary experiments concerning extracting and utilizing characteristic information in supporting nanodevice development. These papers are currently from the same research group (e.g., (Hara et al 2006)). We also started to collaborate with other research groups to enlarge and include different research topics related to nanodevice development.…”