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The well aligned InZnP:Ag nano-rods doped with noble metal Ag were fabricated using ion milling method. Results for XPS coincide with results for AES, especially Ag 3d5. The uniformity, density, and height of InZnP:Ag nano-rods were well formed in TEM measurements. In order to clarify the formation of InZnP:Ag nano-rods, SEM was carried out due to the doping of Ag. XRD measurements were performed in order to support the above TEM results, it is confirmed that the lattice was well aligned without distortion and that the nano-rod was a single crystalline zinc blende structure. The variation of FWHM for TAD peaks demonstrates that noble metal Ag is incorporated into InZnP:Ag nano-rods. The trend of FWHM results coincides with the trend of TEM results according to ion milling depth. The clear opening of the ferromagnetic hysteresis loop indicates the formation of ferromagnetic spin coupling interaction in InP:Zn doped with Ag. The FC M-T curve clearly displays that the ferromagnetism of InZnP:Ag persists near 300 K.

We investigated the effects of the Ti content on the structural and the magnetic properties of ZnCrO:Ti thin films (Cr: 1.0 at.%, Ti: 0 - 0.8 at.%). The samples were prepared by co-sputtering of ZnCrO and Ti and showed the Ti solution limit to be ~0.3 at.%. When the Ti additives were doped with an appropriate concentration less than the solution limit, the magnetic properties of the films were improved due to the increased magnetic moments from Ti2+ ions (i.e., 3d24s0). For the samples doped with large amounts of Ti dopants over the solution limit, however, the magnetization was gradually degraded due to the formation of metastable TiO2 and ZnCrTiO having no spins (i.e., 3d04s0).

We report the room temperature ferromagnetic properties of graphene adsorbed by cobalt oxide using electrochemical method. The cobalt oxide doping onto graphene was carried out in 0.1 M LiCoO 2 /DI-water solution. The doped graphene thin film was determined to be a single layer from Raman analysis. The CoO doped graphene has a clear ferromagnetic hysteresis at room temperature and showed a remnant magnetization, 128.2 emu/cm 3 . The temperature dependent conductivity of the adsorbed graphene showed the semiconducting behavior and a band gap opening of 0.12 eV.

GaN:Mn epilayers were grown on Al 2 O 3 substrate uisng molecular beam epitaxy (MBE) and were subsequently implanted with Mn + ions (1% and 10%). Photoluminescence (PL) with 1% of Mn showed that optical transitions related to Mn revealed the donor-Mn pair (D, Mn) at 2.5 eV and the electron-Mn pair (e, Mn) around 3.1 eV, and yellow luminescence (YL) around 2.20–2.25 eV. Photoluminescence (PL) with 10% of Mn showed the same but enhanced optical transitions as above. However, the new transitions around 1.65 eV for the sample with 10% which did not appeared with Mn of 1% were very weakly produced. The results of cathode-luminescence (CL) with 10% of Mn showed transitions related to Mn in PL together with new transitions around 1.72 eV. However, the new transitions around 1.72 eV for the sample with 10% according to high accelerating voltage were very remarkably activated in contrast with PL transitions which appeared were very weakly produced in samples with Mn of 10%. Transitions around 1.72 eV in CL correspond to though around 1.65 eV in PL. This result means that deep donor (probably, V N ) is detected with increasing accelerating voltage and Mn–V N complex is formed. This is supported by strong electron beam sensitivity of the IR emission bands. It is well known that heavy Mn doping (>∼10 19 C m −3 ) leads to a downshift of the Fermi level and promotes the formation of defect complexes of Mn–V N . In our case, Mn doping concentration is >∼10 21 C m −3 . Therefore, it is conjectured that the CL transition around 1.72 eV corresponds to Mn–V N complex.

We investigated the effect of the Cr content on the magnetic properties of ZnCrO thin films (Cr: 1.0 - 12.5 at.%). Regardless of the Cr concentration, all of the films exhibited clear ferromagnetism even at temperatures above 350 K. For the dependence of spontaneous magnetization on the Cr concentration, however, the magnitude of effective magnetic moment (per Cr ion) was observed to exponentially decrease with increasing Cr content. We attributed the decreased spontaneous magnetization to the degraded crystal magnetic anisotropy. Namely, we found that, in a magnetic-ion-doped thin film, the high concentration of magnetic ions caused a lattice distortion and consequently degraded the ferromagnetic channeling in the solid-state material system.

We report a band gap opening and p-type doping for single layer graphene by an electrochemical method. The chlorine oxide doping to graphene was carried out in 0.1 M LiClO4/acetonitrile solution. The temperature dependent conductivity of the p-type doped graphene at an applied potential of 1.5 V during the electrochemical doping process showed the band gap of 0.094 eV.

We have investigated the ferromagnetic properties of MoS2 thin film doped by iron using chemical vapour deposition. The structure of film was determined to be poly-crystalline with various phases. The iron doped MoS2 film shows that the ferromagnetic hysteresis appears at room temperature, and also indicated two Curie temperatures. The remnant magnetization and coercive field at room temperature are 36 emu/cm3 and 44 Oe. The elemental atomic concentration of iron doped MoS2 measured by x-ray photoelectron spectroscopy was 0.69 at.%.

Above room temperature, ferromagnetic behavior is achieved in Si through Fe ion implantation. The incorporation of Fe in Si was confirmed by an X-ray diffraction and a superconducting quantum interference device. Fe-implanted Si magnetic semiconductors annealed at 800 and 900 ∘C for 25 min were found to have a ferromagnetic ordering with a Curie temperature above room temperature. X-ray diffraction (XRD) measurements strongly revealed that iron silicide were formed, suggesting that the ferromagnetism observed in Fe-implanted Si magnetic semiconductor is due to phase segregation into iron silicide. Even at low implantation dose, we observed the formation of Fe silicide phase responsible for the high temperature magnetic behavior. These measurements strongly support the formation of Fe silicide phase and provide strong evidence of the existence of the Fe silicide phase that determines Curie temperature.

GaN:Mn epilayers were grown on Al2O3 substrate by using molecular beam epitaxy (MBE). Xray diffraction (XRD) data showed intrinsic GaMnN and precipitates including MnGa and MnN. PL transitions (e, Mn) and (D, Mn) related to Mn were remarkably activated. Clear ferromagnetic hysteresis loops were obtained in both samples, which means a good formation of ferromagnetic coupling. The M-T curves revealed a curie temperature (T c ) of 140 ~ 170 K which is intrinsic to GaMnN and a Tc of above 300 K which is due to the MnGa and the MnN precipitates. The samples clearly displayed a magnetic resonance at a field of around 200 - 400 mT. Electron spin resonance (ESR) data showed that the shift of (H center ) (i.e., H center = 337 - H center [mT]) were greater than 20 mT for samples, and the appearance of a Hcenter with a positive H center is indicative of the samples having obvious ferromagnetism. The incorporated Mn ions are in a 2+ ionic state (i.e., Mn2+) because Mn2+ with a spin state of S = 5/2 typically exhibits a magnetic resonance with g ≈ 2 when Mn is doped into semiconductors.

We studied the influence of Mn in multilayer system consisting of twenty layers of InMnGaAs/InGaAs quantum wells (QWs) by low-temperature molecular beam epitaxy (MBE). The incorporation of Mn in the InGaAs was confirmed by X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS). A ferromagnetic ordering with a Curie temperature over 300 K of twenty layers of InGaMnAs/InGaAs QW structure grown on high resistivity (100) p-type GaAs substrates was found. Even at low growth temperature, we observed the formation of GaMn clusters responsible for the high-temperature magnetic behavior. These measurements strongly support the formation of GaMn clusters and provide strong evidence of the existence of the GaMn clusters that determines Curie temperature.

Potassium-doped ZnO thin films electrodeposited on indium tin oxide (ITO) coated glass substrates exhibited ferroelectric behavior with a remnant polarization of 0.2 µC/cm2. Especially, wave forms showing the applied input voltage Vi and output voltage Vo were obtained for Al/ZnO:K/ITO structure. It exhibits a superposition of Vi (input) and Vo (output) signal from Al/ZnO:K/ITO structure with a clear phase shift between the two wave forms which again confirms that the observed ferroelectric hysteresis curve is not related to leaky dielectric materials. The current–voltage characteristics of Al/ZnO:K/ITO structures measured for several cycles revealed bi-stable switching characteristics. The reproducible bi-stable switching characteristics for the mentioned structures had good retention in one particular resistance state. Around one order of switching was realized between low and high resistance states. The switching property thought to be polarization induced originating out from the ferroelectric properties of the potassium doped ZnO thin film. The switching between ZnO:K/ITO interface is assumed to be critical for stability in switching for several cycles. Possible application of this structure in non-volatile memories is explored.

We report a ferromagnetic graphene field-effect transistor with a band gap. The Mn-doped graphene has a coercive field (Hc) of 188 Oe and a remanent magnetization of 102 emu cm−3 at 10 K. The temperature-dependent conductivity indicates that the Mn-doped graphene has a band gap of 165 meV. A fabricated graphene FET revealed p-type semiconducting behavior, and the field effect mobility was determined to be approximately 2543 cm2 V−1 s−1 at room temperature.

Magnetocaloric effect of the Ni–Co–Mn–Al quaternary alloys was evaluated with the aim of fine-tuning the composition such that the temperature at which the maximum entropy change (|ΔSM|pk) occurs coincided with room temperature. Out of the three alloys tested (Ni41.5Co8.5Mn32Al18, Ni41Co9Mn32.5Al17.5 and Ni41Co9Mn32Al18), Ni41Co9Mn32Al18 was optimal with |ΔSM|pk of 2.1 J kg−1 K−1 at 10 kOe observed at 300 K as designed and the refrigeration capacity (RC) was 52 J kg−1. Both values do compare favorably with other Heusler-type alloys, considering the relatively low material cost of the Ni–Mn–Al alloy. In addition, Ni41.5Co8.5Mn32Al18 and Ni41Co9Mn32Al18 alloys were chemically joined (using an epoxy) to attain |ΔSM|pk and RC values that nearly corresponded to the average values of the original alloys, providing a method for further tailoring the magnetic properties of the refrigerant in addition to the refinement of the composition.

InCrP:Zn was prepared using the implantation with Cr concentrations of 0.3% and 0.7%, respectively. It was confirmed that the photoluminescence peaks near 0.85(D, Cr) eV and 0.96(e,Cr) eV were Cr-correlated PL bands by the implantation of Cr. Especially, each 0.85(D, Cr) eV and 0.96(e,Cr) eV peaks were separately observed based on InP. In triple-axis x-ray diffraction patterns, the samples revealed a shoulder peak indicative of intrinsic InCrP. Ferromagnetic hysteresis loops measured at 10 K and 300 K were observed and the temperature-dependent magnetization showed ferromagnetic behavior ≥300 K, which reveals obvious and enhanced ferromagnetic spin coupling mediated by hole.

In the present study, Mn/graphene/SiO2 films have been successfully prepared by spin coating a manganese dinitrate hydrate standard solution (10,000 μg/mL Mn+2 in 2% HNO3) on a graphene/SiO2 sheet. The samples were characterized by using an X-ray diffractometer, a scanning electron microscope, a superconducting quantum interference device and an atomic force microscope. The magnetic measurement revealed that the Mn/graphene/SiO2 films exhibited a ferromagnetic behavior at 5 K and 300 K. We concluded that the ferromagnetism observed in the Mn/graphene/SiO2 sheets was associated with parasitic ferromagnetic Mn clusters imposed on the antiferromagnetic structure of MnO2, which might have resulted from a distortion of the lattice structure due to oxygen vacancies, which might have been due to the effects of magnetic and structural disorder introduced by a random incorporation and inhomogeneous distribution of Mn atoms in the graphene layer.

A ferromagnetic ordering with a Curie temperature of 50 K of fifteen layer of InGaMnAs/GaAs multi quantum wells (MQWs) structure grown on high resistivity (100) p-type GaAs substrates by molecular beam epitaxy (MBE) was found. It is likely that the ferromagnetic exchange coupling of sample with Curie temperature of 50 K is hole-mediated resulting in Mn substituting In or Ga sites. Temperature and excitation power dependent PL emission spectra of InGaMnAs MQWs sample grown at temperature of 170 °C show that an activation energy of Mn ion on the first quantum confinement level in InGaAs quantum well is 36 meV and impurity Mn is partly ionized. It is found that the activation energy of 36 meV of Mn ion in the QW is lower than the activation energy of 110 meV for a substitutional Mn impurity in GaAs. These measurements provide strong evidence that an impurity band existing in the bandgap due to substitutional Mn ions and it is the location of the Fermi level within the impurity band that determines Curie temperature.

The p-type InP:Be/Mn/InMnP:Be triple epilayers were prepared using MBE to increase T c (>300 K) by preventing MnO 2 . After milling 1–3 nm of epilayers thickness from the top surface, the transmission electron microscopy (TEM) and X-ray diffraction (XRD) revealed no MnO 2 and precipitates, and TEM and XRD results coincide with results of ferromagnetism. The enhanced ferromagnetic transition at >300 K corresponds to InMnP:Be. The increased ferromagnetic coupling without MnO 2 is considered to originate from the increased p–d hybridation. These results demonstrate that InP-based ferromagnetic semiconductor layers having enhanced ferromagnetism can be formed by above process.

Ten layers of InGaMnAs/GaAs multiquantum wells (MQWs) structure were grown on high resistivity (100) p-type GaAs substrates by molecular beam epitaxy (MBE). A presence of the ferromagnetic structure was confirmed in the InGaMnAs/GaAs MQWs structure, and have ferromagnetic ordering with a Curie temperature, T C=50 K. It is likely that the ferromagnetic exchange coupling of the sample with T C=50 K is hole-mediated resulting in Mn substituting In or Ga sites. PL emission spectra of the InGaMnAs MQWs sample grown at a temperature of 170 °C show that an activation energy of the Mn ion on the first quantum confinement level in InGaAs QW is 32 meV and impurity Mn is partly ionized. The fact that the activation energy of 32 meV of Mn ion in the QW is lower than an activation energy of 110 meV for a substitutional Mn impurity in GaAs, indicating an impurity band existing in the bandgap due to substitutional Mn ions.

We fabricated high quality epitaxial Bi 0.9 Ho 0.1 FeO 3 thin films which exhibited the tetragonally stained structure with a c / a ratio of about 1.04. The Bi 0.9 Ho 0.1 FeO 3 thin film showed a good ferroelectric property with the high remanent polarization ( P r ) of about 80 μC/cm 2 . The ferromagnetic hysteresis loop with a clear remanent magnetization was shown. The coercive field and the remanent magnetization of the Bi 0.9 Ho 0.1 FeO 3 film are 6200 Oe and 1.7 emu/g, respectively. The abrupt conduction due to space charge limited (SCL) was revealed in leakage current density versus electric field.

We have investigated the optical properties of vertical GaN nanorods with diameters of 150 nm grown on (111) Si substrates by radio-frequency plasma-assisted molecular-beam epitaxy followed by Mn ion implantation and annealing. The GaN nanorods are fully relaxed and have a very good crystal quality characterized by extremely strong and narrow photoluminescence excitonic lines near 3.47 eV. For GaMnN nanorods, Arrhenius plots of the intensities of the Mn acceptor give a thermal activation energy of Δ=350 meV, indicating that the thermal quenching of the Mn-related PL peak is due to the dissociation of an acceptor-bound hole from the temperature-dependent PL spectra. This suggests that the Mn-bound holes in GaN nanorods exhibit the impurity states predicted by the hydrogen model.

p-type InP:Zn epilayers were grown by using metalorganic chemical vapor deposition. After the growth of InP:Zn epilayers, Mn was evaporated on top of the InP:Zn epilayers by using a molecular beam epitaxy system. Then, Mn was diffused into the InP:Zn epilayers by annealing. InMnP:Zn epilayers were annealed at 600 °C for 60 s with Mn concentrations of both ∼1.5 and ∼3.0%. The optical transitions related to Mn appeared at 1.144, 1.187, and 1.212 eV and at 1.143, 1.179, and 1.205 eV for InMnP:Zn epilayers annealed at 600 °C for 60 s with Mn concentrations of ∼1.5 and ∼3.0%, respectively. Transitions related to Mn are noticeably activated due to an increase in the Mn concentration near 3.0% in comparison with transitions for Mn concentration near 1.5%. Clear ferromagnetic hysteresis loops were obtained for InMnP:Zn epilayers. The ferromagnetic hysteresis loop of the InMnP:Zn epilayers annealed with Mn concentration near 3.0% was bigger than that of epilayers with Mn concentration near 1.5%, and these results agree with the PL results that transitions related to Mn are remarkably activated upon annealing at Mn concentration near 3.0% in comparison with concentration near 1.5%. Ferromagnetic behavior persisted up Tc1 ∼ 50 K and Tc2 ∼ 291 K. Tc2 ∼ 291 K corresponds to MnP. Tc1 ∼ 50 K originates from intrinsic InMnP:Zn, which is caused by carrier-mediated ferromagnetism in the InMnP:Zn epilayer. We found that at Tc1 ∼ 50 K, a ferromagnetic semiconductor could be formed in a diluted magnetic semiconductor based on InMnP:Zn epilayers additionally co-doped with Zn.

The ferromagnetic semiconductor p-InMnP:Zn epilayers were prepared through low-temperature annealing at 250 °C by using Mn/InP:Zn bilayers. The p-type InP:Zn epilayers were prepared by using metal-organic chemical vapor deposition. Then, ultra-thin Mn layers were subsequently deposited onto the layers by using molecular beam epitaxy. The Mn/InP:Zn bilayers were annealed at a low temperature of 250 °C in order to minimize the formation of precipitates such as InMn, MnP, Mn2P, and Mn3In. No ferromagnetic precipitates were observed in the annealed InMnP:Zn; however, the sample exhibited an antiferromagnetic phase of MnO2 that might have been formed because of an unavoidable surface oxide that had been created during the sample transfer. Despite the existence of antiferromagnetic MnO2, the samples revealed clear ferromagnetic hysteresis loops and showed high ferromagnetic transition temperatures up to ∼180 K. The results suggest that a ferromagnetic semiconductor InMnP:Zn can be effectively formed through low-temperature annealing by using a Mn/InP:Zn bilayer.

We investigated the carrier transition properties of the GaN/InGaN/GaN single quantum well bounded by AlGaN barriers. In order to confirm the carrier transition coming from the single quantum well, the single quantum well layer was etched by reactive ion etching method. The structural property of the samples was characterized by high resolution X-ray diffraction measurements. In micro-photoluminescence measurements, it is clearly shown that the donor bound exciton transition of the single quantum well sample was redshifted compared to the etched one due to strain. Moreover, a lot of peaks were observed below the GaN band gap energy due to carrier localization in the InGaN/GaN single quantum well, including carrier localization center and quantum confined states. The excitation power dependence and time resolved photoluminescence spectra were investigated to characterize the optical transition of the single quantum well© 2011 Elsevier B.V. All rights reserved.

We report on the ferroelectric and ferromagnetic behaviors of a Mn doped GaAs epilayer grown on a GaAs (111) substrate by molecular beam epitaxy. We investigated the structural, electrical, and ferromagnetic properties of the Mn doped GaAs epilayer by high resolution x-ray diffraction, anomalous Hall effect, and superconducting quantum interference device measurements. We obtained the ferromagnetic and ferroelectric Curie temperature to be 50 K and 350 K, respectively, which were confirmed by the anomalous Hall effect, temperature dependence of magnetization, and tan δ vs. temperature. Furthermore, we demonstrated ferroelectric switching behaviors of the Mn doped GaAs epilayer by electric force microscopy.

The thermodynamic behavior of excitonic emission properties in manganese- and zinc-codoped indium phosphide (InMnP:Zn) diluted magnetic semiconductor (DMS) layers was investigated. Compared to the InMnP:Zn DMS layer (Mn ≈ 0.06%), the inhomogeneous thermal-broadening of the excitonic-emission line-width in InMnP:Zn DMS layer (Mn ≈ 0.29%) is dominant at lower temperatures. This is attributed to the increase of ionized impurity scattering from Mn ions and results in the increase of exciton–phonon coupling strength. As a consequence, high Mn content can lead to low excitonic emission efficiency, although generally a larger Mn content is favorable to increase the Curie temperature of a DMS material.

1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) phospholipid membrane was used to fabricate a tightly packed 2-dimensional array of Sn nanoparticles through direct deposition of Sn on the DOPC membrane. Major advantage of the proposed method was that the vertical ordering of the nanoparticles extended to a centimeter (2 cm × 2 cm substrate) scale in the as-prepared state. It was also shown that the particle size and morphology were altered depending on processing conditions. Experimental evidences indicated that the Sn nanoparticle surface, which spontaneously oxidized during deposition, was encapsulated by the DOPC molecules. After removing the encapsulating lipid layer, the oxide-covered Sn nanoparticles exhibited strong photoluminescence. It was also demonstrated that the Sn particle morphology and ordering are related to the lipid membrane structure and chemistry. The proposed method can be easily extended to other metals that are susceptible to oxidation to produce various metal oxide nanoparticles.

Ten layers of self-assembled InMnAs quantum dots with InGaAs barrier were grown on high resistivity (1 0 0) p-type GaAs substrates by molecular beam epitaxy (MBE). The presence of ferromagnetic structure was confirmed in the InMnAs diluted magnetic quantum dots. The ten layers of self-assembled InMnAs quantum dots were found to be semiconducting, and have ferromagnetic ordering with a Curie temperature, TC=80 K. It is likely that the ferromagnetic exchange coupling of sample with TC=80 K is hole mediated resulting in Mn substituting In and is due to the bound magnetic polarons co-existing in the system. PL emission spectra of InMnAs samples grown at temperature of 275, 260 and 240 °C show that the interband transition peak centered at 1.31 eV coming from the InMnAs quantum dot blueshifts because of the strong confinement effects with increasing growth temperature.

We report a photoluminescence detected anticrossing of the energy levels in an undoped asymmetric coupled-double-quantum-well buried in a p-i-n structure. Due to the built-in electric field, the quantum wells are tilted in such a way that the symmetric energy level is higher than that of the antisymmetric one in the conduction band. Keeping the laser excitation energy below the barrier, with increasing laser power, the level anticrossing and the quantum confined Stark effect were observed due to decreasing built-in electric field by the photogenerated electron and hole pairs.

The excitation density dependent photoluminescence (PL) spectra in Ga1−xMnxN layers (where x≈0.1–0.8%) grown on sapphire (0 0 0 1) substrates using the plasma-enhanced molecular beam epitaxy technique have been investigated. The efficient PL peaks are observed in the red (1.86 eV), yellow (2.34 eV), and blue (3.29 eV) spectral ranges. By examining the dependence of PL on the excitation laser power density at 15 and 300 K, the yellow band (2.34 eV) and bandgap (3.50 eV) luminescence vary linearly with the light intensity, which are in good agreement with a simple recombination model, which assumes a density of recombination centers below the conduction band edge.

The p-type InMnP:Be epilayers, which were prepared by thermal diffusion of Mn through in-situ deposition of Mn layer using molecular beam epitaxy (MBE) onto MBE-grown InP:Be epilayers and subsequent in-situ annealing at 300–350 °C, were investigated. InMnP:Be epilayers prepared by the above sequence clearly showed the Mn-related emission band at 1.1–1.2 eV, which indicates the effective incorporation of Mn 2+ ions into the host layer InP:Be. The samples demonstrated very large ferromagnetic hysteresis loops with enhanced coercivity, and the ferromagnetic-to-paramagnetic transition of the samples was observed to occur at ∼85 K. These results suggest that InP-based ferromagnetic semiconductor layers having enhanced ferromagnetism can be effectively formed by the above-mentioned sequential in-situ processes.

The formation, including the density and height of the InFeP:Ag nanorods doped with noble metal Ag using an ion milling method, was preponderantly determined from transmission electron microscopy and x-ray diffraction analyses. We investigate, in particular, the enhanced ferromagnetism of the well-aligned InFeP:Ag nanorods. Auger electron spectroscopy and x-ray photoelectron spectroscopy measurements were carried out in order to investigate the incorporation of Ag and to verify the local chemical bonding of the InFeP:Ag nanorods. The variation of FWHM for the double-crystal x-ray rocking curve and triple-axis diffraction peaks demonstrates that noble metal Ag is incorporated into the InFeP:Ag nanorods. The noticeable ferromagnetic signature (M-H curve) of the InFeP:Ag nanorods is observed and T c persists up to almost 350 K (3.9 × 10-4 emu g-1), as determined by temperature-dependence magnetization (M-T curve) measurements. This study suggests that the InFeP:Ag nanorods should be a potential candidate for the application of spintronic devices.

GaMnN and GaMnN:Mg layers were prepared using implantation of 5 and 10 at.% Mn ions into undoped GaN and p-type GaN:Mg, respectively. Both samples revealed that two precipitate phases, Ga5:2Mn and Mn3Ga, coexist with the crystalline phase GaMnN. The ferromagnetic transition showed two kinds of behaviors; i.e., a rapid transition from GaMnN at lower temperatures (75 100 K) and a released transition from Ga5:2Mn and Mn3Ga at higher temperatures (above 300 K). The TC of GaMnN for Mg-codoped GaMnN ( 100 K) was observed to be higher than that for undoped GaMnN ( 75 K).

High quality ZnO films were made by using a pulsed laser deposition (PLD) system. Through a same method magnetic element doped Zn(Mn,Co)O films were grown. An XRD measurement was tried and the result showed a single crystal of wurtzite structure. A capacitance-voltage measurement showed that the ZnMnO has electrical properties of an n-type semiconductor, and carrier concentration is 5 × 1018 cm-3. From a deep level transient spectroscopy (DLTS) measurement, an oxygen vacancy and a Mn-related electron trap in the ZnMnO film were appeared as Ec-0.62 eV and Ec-0.13 eV, respectively. The electrical measurement of the ZnCoO films showed meaningless results because of its high conductance.

Mn+-implanted and annealed Si1−xGex thin films grown on p-Si (100) substrates were formed with the goal of producing (Si1−xGex)1−yMny with a high ferromagnetic transition temperature ( T c ) . The double-crystal X-ray rocking curves and transmission electron microscopy images showed that the Mn-implanted and annealed Si1−xGex thin films were single crystalline. The magnetization curves as functions of the magnetic field clearly showed that ferromagnetism existed in the Mn + -implanted and annealed Si1−xGex thin films, and the magnetization curves as functions of the temperature showed that the T c value was above 300 K. These results indicate that the formed (Si1−xGex)1−yMny thin films hold promise for potential applications in Si-based spintronic devices operating at room temperature.

In this paper, we studied the electrical and optical properties of magnetic impurities and non-magnetic impurities of p-type InMnP:Zn co-doped with Zn by using electrical measurements such as capacitance-voltage (C-V), deep level transient spectroscopy (DLTS), and photo-induced current transient spectroscopy. In the InMnP:Zn used in this study, ion implantation to InP:Zn and post annealing methods are used to achieve the effective substitutions of the In+-cations by Mn+-magnetic ions.

The temperature-dependent photoluminescence (PL) properties of the As-doped (Zn 0.93 Mn 0.07 )O layer, which showed the stable p -type conductivity with carrier concentration of ∼ 10 18 cm − 3 and carrier mobility of ∼ 10 cm 2 V − 1 s − 1 , were investigated. From fitting of the Bose–Einstein approximation using extracted emission parameters from temperature-dependent PL spectra, it was found that the interaction between exciton and phonon in p -(Zn 0.93 Mn 0.07 )O:As is higher than that in host material ZnO. This result was confirmed as resulting from the increase of disorder-activated phonon scattering which is attributed to the increase of free carriers donated from implanted As dopants.

Low-resistance and high-transparency cobalt-doped indium–tin oxides (ITO) showing ferromagnetic behavior were obtained by magnetron cosputtering technique. The majority of Co atoms occupied In (or Sn) sites of ITO at 8% doping, leading to hole generation and a concomitant ferromagnetic response with a maximum magnetization of approximately 0.26 µB/Co. As the Co concentration increased to 14%, oxide precipitates were formed. The resistivity at 8% doping was as low as 4.28×10-3 Ωcm. The optical transmissions at 460 nm and 520 nm reached maximums of 72.7% and 86.6%, respectively.

The p-type InP:Zn was prepared by the liquid encapsulated Czochralski method and subsequently implanted with Mn + of 5 × 10 15 cm −2 . The results of energy dispersive X-ray displayed that the concentration of incorporated Mn into InP:Zn is 1 at.%. The cross-sectional transmission electron microscopy showed that the thickness of Mn-incorporated layer was ∼300 nm. For photoluminescence measurements, the Mn-related optical transitions caused by incorporation of Mn were broadly observed at the energy region of 1.034, 0.985, and 0.958 eV. The samples clearly showed ferromagnetic hysteresis loops at 10 K, and the ferromagnetic behavior was observed to persist up to 360 K. Thus, the Curie temperature of Mn + -implanted InMnP:Zn (Mn ∼ 1 at.%) is expected to be above 300 K. It is found that a room-temperature-ferromagnetism of InMnP:Zn can be formed by ion implantation of a relatively low concentration of Mn (1 at.%).

We studied defect states of Mn-implanted p-type InP:Zn samples annealed at 450, 550, and 600 ∘ C by using C–V and deep level transient spectroscopy (DLTS) measurements. From these results, it was confirmed that ion implantation process make defects in the InP. Thermal annealing process could reduce the crystal defects and increase the crystallinity of the InMnP. We could find clear DLTS signal name as HL1, HL2, and HL3, and then their activation energies and cross-sections were obtained about 0.43 , 0.29 , 0.65 eV and 3.09 × 10 - 13 cm 2 , 1.23 × 10 - 18 cm 2 , 3.17 × 10 - 13 cm 2 , respectively. Among them, the origin of HL2 signal was considered to be a Mn-related level. Finally we confirmed that the ferromagnetic properties of InMnP:Zn are affected by this Mn-related levels and the sample crystallinity.