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Diffusion of Interstitial Mn in the Dilute Magnetic Semiconductor (Ga,Mn)As: The Effect of a Charge State
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.ORCID-id: 0000-0002-9920-5393
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
2008 (Engelska)Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 17, s. 177204-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Migration barriers for diffusion of interstitial Mn in the dilute magnetic semiconductor (Ga,Mn)As are studied using first-principles calculations. The diffusion pathway goes through two types of interstitial sites: As coordinated and Ga coordinated. The energy profile along the path is found to depend on the ratio of concentrations between substitutional and interstitial Mn in GaAs. Two regions of distinctly different behavior, corresponding to n-type and p-type (Ga,Mn)As, are identified. The difference in mobility is a reflection of the change in the charge state of Mn interstitials (double donors) that occurs in the presence of substitutional Mn impurities (acceptors). In addition, substitutional Mn impurities are shown to act as traps for interstitial Mn. The effective migration barrier for the positively doubly charged Mn interstitials in p-type (Ga,Mn)As is estimated to vary from 0.55 to about 0.95 eV.

Ort, förlag, år, upplaga, sidor
2008. Vol. 101, nr 17, s. 177204-
Nyckelord [en]
DILUTE MAGNETIC SEMICONDUCTOR, ELECTRONIC STRUCTURE, DEFECTS, DIFFUSION
Nationell ämneskategori
Den kondenserade materiens fysik Annan elektroteknik och elektronik Fysikalisk kemi
Identifikatorer
URN: urn:nbn:se:kth:diva-7895DOI: 10.1103/PhysRevLett.101.177204ISI: 000260383600060Scopus ID: 2-s2.0-55049107277OAI: oai:DiVA.org:kth-7895DiVA, id: diva2:13059
Anmärkning

QC 20100624

Tillgänglig från: 2008-01-15 Skapad: 2008-01-15 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
Ingår i avhandling
1. Point defect interactions and structural stability of compounds
Öppna denna publikation i ny flik eller fönster >>Point defect interactions and structural stability of compounds
2007 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Theoretical studies of point defect interactions and structural stability of compounds have been performed using density functional theory. The defect-related properties, such as activation energy of diffusion, electronic and magnetic structure of selected materials have been studied.

The major part of the present work is devoted to a very important material for semiconductor industry, GaAs. The formation energies of intrinsic point defects and the solution energies of 3d transitions in GaAs have been calculated from first principles. Based on the calculated energies, we analysed the site preference of defects in the crystal. The tendency of defects to form clusters has been investigated for the intrinsic defects as well as for impurities in GaAs. The magnetic moment of 3d impurities has been calculated as a function of the chemical environment. The possibility of increasing the Curie temperature in (Ga,Mn)As by co-doping it with Cr impurities has been examined on the basis of calculated total energy difference between the disordered local moment and the ferromagnetically ordered spin configurations. We found that, in order to reach the highest critical temperature, GaAs should be separately doped with either Cr or Mn impurities. Also, we have shown that diffusion barrier of interstitial Mn depends on the charge state of this impurity in (Ga, Mn)As. The formation of defect complexes between interstitial and substitutional Mn atoms, and their influence on the value of diffusion barrier for interstitial Mn, has been studied.

The pair interactions energies between interstitial oxygen atoms in hcp Zr, Hf and Ti have been calculated using first principles. Based on the calculated energies, the oxygen ordering structures in IVB transition metal solid solutions have been explained. A prediction of nitrogen ordering in Hf-N solid solution has been made.

The thermodynamic description of intermetallic compounds in the Zr-Sn binary system has been obtained. The conclusion has been made that Zr substitution on the Sn sites takes place in the Zr4Sn phase, which accounts for the unusual stoichiometry of this Cr3Si structure type compound.

The influence of pressure on the phase stability in the Fe-Si system has been investigated. We have found instability of the hcp Fe0.9Si0.1 random alloy with respect to the decomposition onto the Si-poor hcp Fe alloy and the B2 FeSi under high pressure. The tendency of this decomposition becomes stronger with increasing the applied pressure.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH, 2007
Nyckelord
first principles, ab initio, density functional theory, point defects interactions, diluted magnetic semiconductors, structural stability, zirconium alloys
Nationell ämneskategori
Annan materialteknik
Identifikatorer
urn:nbn:se:kth:diva-4605 (URN)978-91-7178-842-9 (ISBN)
Disputation
2008-01-28, Sal F3, KTH, Lindstedtsvägen 26, Stockholm, 10:00
Opponent
Handledare
Anmärkning
QC 20100624Tillgänglig från: 2008-01-15 Skapad: 2008-01-15 Senast uppdaterad: 2012-03-19Bibliografiskt granskad

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Korzhavyi, Pavel A.

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