Possible origin of ferromagnetism in (Ga,Mn)N

Zając, M.; Gosk, J.; Grzanka, Ewa; Kamińska, M.; Twardowski, A.; Strojek, B.; Szyszko, T.; Podsiadło, S.

doi:10.1063/1.1559939

Cited by 102 publications

(77 citation statements)

References 22 publications

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“…Antiferromagnetic GaMn 3 N precipitates have previously been observed in Wurtzite (Ga,Mn)N at high Mn concentrations [16]. Although Mn 4 N phases are not usually identified in MBE-grown (Ga,Mn)N, this is a known room temperature ferromagnet, and undetected inclusions of this or other magnetic secondary phases may be responsible for the room temperature ferromagnetic properties observed here as well as elsewhere [17]. For the (Ga,Mn)N (002) reflection, no significant shift in the peak position on varying the Mn concentration between zero and 10% can be resolved, due to the large width of the 002 reflection.…”

Section: Growth and Structurementioning

confidence: 77%

“…Comparing the measured room temperature ferromagnetism to the Mn concentration measured by SIMS, we obtain a magnetic moment of only around 0.1 µ B / Mn, indicating that most of the Mn in the sample is not contributing to the room temperature coupling. The origin of this signal is not presently known, however it has been noted that there are several Mn x N y phases which have a ferromagnetic transition temperature above room temperature [17], which could account for the observed behaviour. Here we take the view that, in order to 6 understand the magnetic properties of (Ga,Mn)N, it is important to study the system as a whole rather than concentrating only on the small room temperature ferromagnetic part (we note however that the opposite approach is frequently taken in the experimental literature surrounding (Ga,Mn)N).…”

Section: Magnetic Propertiesmentioning

confidence: 96%

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p -type conductivity in cubic (Ga,Mn)N thin films

Edmonds

Novikov

Sawicki

et al. 2005

Applied Physics Letters

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The electrical and magnetic properties of p-type cubic (Ga,Mn) IntroductionThe emerging field of semiconductor spintronics relies on the ability to manipulate the electron spin in a semiconductor device, thus offering new prospects for non-volatile high speed information storage and processing. An important milestone in this field was the discovery of carrier-mediated ferromagnetism in III-V compounds doped with Mn [1]. Intensive efforts have since led to ferromagnetic transition temperatures T C in excess of 150K in (Ga,Mn)As [2,3,4], and an impressive range of prototype devices [5,6,7]. However, for widespread technological usage of these systems, a T C significantly above 300K is necessary, which may yet require the development of new materials.In this context, the Zener mean-field model prediction of room temperature ferromagnetism in (Ga,Mn) , a value significantly higher than the highest hole concentrations so far obtained in GaN. Furthermore, optical measurements have indicated that the Mn acceptor level lies over 1eV above the valence band maximum in Wurtzite (Ga,Mn)N [9,10], which is in agreement with density-of-states calculations [11]. Therefore, in contrast to the case for (Ga,Mn)As, Mn does not appear to be an efficient acceptor in Wurtzite GaN, and may not be expected to interact strongly with delocalised charge carriers in the conduction or valence bands. In spite of this, there are numerous observations of room temperature ferromagnetism in n-type (Ga,Mn)N, even in cases where no secondary phases have been identified [12]. The origin of the ferromagnetism in these cases is unresolved, but no conclusive evidence for a coupling between magnetic and semiconductor properties has been demonstrated, and it appears that this effect lies outside the Zener model prediction.It may be expected that Mn incorporation is favoured in the metastable zincblende (cubic) phase of GaN, since MnN is itself cubic with a similar lattice constant to GaN. at room temperature [14]. Cubic (Ga,Mn)N may therefore be a more promising candidate than the Wurtzite phase for room temperature carrier-mediated ferromagnetism. It is important to determine the origin of the p-type conductivity and investigate the nature of the Mn state in this material. Here we report on a detailed study of the electrical and magnetic properties of cubic (Ga,Mn)N films grown on GaAs(001) by molecular beam epitaxy. Growth and structureUndoped cubic GaN films and cubic (Ga,Mn)N layers were grown on semi-insulating GaAs (001) substrates by plasma-assisted molecular beam epitaxy (PA-MBE) using arsenic as a surfactant to initiate the growth of cubic phase material [15]. Films where grown under Nrich conditions, which has been found to be necessary for the effective substitutional incorporation of Mn in hexagonal (Ga,Mn)N [16]. The substrate temperature was measured using an optical pyrometer. Growth temperatures from 450 to 680 o C were used. The active nitrogen for the growth of the group III-nitrides was provided by an CARS25 RF activated plasma source...

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Section: Growth and Structurementioning

confidence: 77%

Section: Magnetic Propertiesmentioning

confidence: 96%

p -type conductivity in cubic (Ga,Mn)N thin films

Edmonds

Novikov

Sawicki

et al. 2005

Applied Physics Letters

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“…It has been theoretically and experimentally suggested that the Mn level is too deep in the GaN band gap to be an effective acceptor [7][8][9], explaining why ptype conduction is not generally observed. Therefore, the reported ferromagnetism has been ascribed to undetected metallic secondary phases [11,12].…”

Section: School Of Physics and Astronomy University Of Nottingham Nmentioning

confidence: 99%

P-type conductivity in cubic GaMnN layers grown by molecular beam epitaxy

Novikov¹,

Edmonds

Giddings

et al. 2003

Semicond. Sci. Technol.

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Cubic (zinc-blende) Ga 1-x Mn x N layers were grown by plasma-assisted molecular beam epitaxy on GaAs (001) substrates. Some of the structures also contained cubic AlN buffer layers. Auger Electron Spectroscopy and Secondary Ion Mass Spectroscopy studies clearly confirmed the incorporation of Mn into cubic GaN, the Mn being uniformly distributed through the layer. X-ray diffraction studies demonstrated that the Mn-doped GaN films are cubic and do not show phase separation up to a Mn concentrations of x<0.1. P-type conductivity for the cubic Ga 1-x Mn x N layers was observed for a wide range of the Mn doping levels. The measured hole concentration at room temperature depends non-linearly on the Mn incorporation and varies from 3x10

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“…In some parts ( suggests the presence of ferromagnetic precipitations in our crystals. Such situation is commonly found in GaN--based DMS [9]. Detailed analysis of the M (B) data allows a reasonable subtraction of the FM phase contribution [1].…”

Section: Resultsmentioning

confidence: 99%