Manganese (Mn) doped III-V dilute ferromagnetic semiconductors (DFSs) are a candidate materials for semiconductor spintronics due to their intrinsic ferromagnetism
mediated by holes. In this thesis, Mn doped III-V dilute ferromagnetic semiconductors (DFSs), including (Ga,Mn)As, (In,Mn)As, (Ga,Mn)P, and (In,Ga,Mn)As have been
successfully prepared by ion implantation and pulsed laser melting. All (In,Ga,Mn)As films are confirmed to be well recrystallized and ferromagnetic while their Curie
temperatures depend on the Ga concentration. (Ga,Mn)As and (Ga,Mn)P have an inplane easy axis, while an out-of-plane easy axis for (In,Mn)As is observed. However,
all of them do not present strong in-plane uniaxial anisotropy between [110] and [110] directions, which always occurs in low temperature molecular beam epitaxy (LT-MBE)
grown (Ga,Mn)As samples. The reason is ascribed to the fact that the ultra-fastrecrystallization induced by pulsed laser melting weakens the formation of Mn-Mn
dimers along the [100] direction which occurs in LT-MBE grown (Ga,Mn)As. Then selected samples were co-doped with Zn or irradiated with He ions. The Zn
co-doping leads to the increase of conductivity of (Ga,Mn)P, however both the Curie temperature and magnetization decrease, which is probably due to the suppression of
active Mn substitution by Zn co-doping. By using Rutherford Backscattering Spectroscopy and Particle-Induced X-ray Emission, the substitutional Mn atoms in
(Ga,Mn)As are observed to shift to interstitial sites, while more Zn atoms occupy Ga sites. This is consistent with first-principles calculations, showing that the formation
energy of substitutional Zn and interstitial Mn is 0.7 eV lower than that of interstitial Zn and substitutional Mn. For ion irradiated (Ga,Mn)As, (In,Mn)As and (Ga,Mn)P,
both Curie temperature and magnetization decrease due to the hole compensation. However, the compensation effect is the strongest in (In,Mn)As and the least in
(Ga,Mn)P. This is due to the different energy level of the produced defect relative to the band edges in different semiconductors. The results in the thesis point to an important issue: the difference in the band alignment and the hole binding energy of Mn dopants in different III-Mn-V dilute ferromagnetic semiconductors have strong influence on their magnetic properties and should be taken into account in the material design.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:79186 |
| Date | 16 May 2022 |
| Creators | Xu, Chi |
| Contributors | Helm, Manfred, Fassbender, Jürgen, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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