Mn-doped InP Research Articles

Non-volatile memory field effect transistor composed of ferroelectric Mn-doped InP thin films and single-layer MoS2 channel

Ferroelectric properties can be generated by doping semiconductor thin films of ZnO and InP with a transition metal such as Mn. Furthermore, ferroelectric thin films exhibiting ferroelectric properties can be utilized as non-volatile memory components, potentially replacing conventional flash memory. In this study, we investigated non-volatile memory properties using field-effect transistors (NVMFET) fabricated from Mn-doped InP (MIP) thin films and single-layer MoS2 sheets. The 5 % Mn-doped MIP thin films exhibited a larger remanent polarization of 8.2 μC/cm2 compared to the 3 % Mn-doped films with 5.1 μC/cm2. The NVMFET devices, operating as non-volatile memory devices, demonstrated a distinct memory window for current changes. Notably, enhancing the remanent polarization of the 5 % Mn-doped MIP thin film further improved the memory window of the corresponding NVMFET.

Delayed fluorescence of InP:Mn/ZnS nanocrystals

The photoluminescence properties of ZnS-capped Mn-doped InP nanocrystals are shown to be determined by the high ratio of the radiative rate constants of the host and dopant emission, by the polydispersity-induced inhomogeneous broadening, and by the rapid establishment of thermal equilibrium in the distribution of the excitation between the energy levels of the quantum dot and the dopant ion. Because of the combination of these factors, the resulting photoluminescence includes the delayed host fluorescence and the quenched dopant phosphorescence, both having very broad lifetime distributions.

Mapping the Identity of Transition Metal Doping and Surface Passivation in Indium Phosphide with Theoretical Calculation.

Understanding the electronic structure of doped InP quantum dots (QDs) is essential to optimize the material for specific optoelectronic applications. However, current synthesis approaches are often tedious and unfavorable for rational tunning. Herein, a combination of experimental and computational studies was conducted to address the doping mechanism and surface passivation of InP QDs. The successful dopant introduction requires low Cu doping concentration and heavy Mn doping, while the Ag doping amount is relatively moderate. This may correspond to the theoretical doping formation energy presented as Cu (-2.52 eV) < Ag (-1.76 eV) < Mn (-0.38 eV). As for surface passivation, inorganic ions and shell-like ZnS are unraveled through simulational investigation. Chloride ion promotes oriented growth toward tetrahedron morphology while nitrate-passivated InP QDs exhibit blurry transmission electron microscope (TEM) morphology. Correspondingly, the binding energy of chloride ion with (111) facet is -2.13 eV significantly lower than those of (110) and (100) facets. Further, the additional Zn 3d bands are more involved in the formation of conduction band, which optimized the Mn-doped InP with a 0.32 eV bandgap. These experimental and model results provide more microscopic details of doped InP, which can motivate theoretically exact control of guest ion stoichiometry with optimized characteristics for electrical devices.

Local strain-induced ferromagnetism in inhomogeneous Fe-implanted silicon carbide

Despite an intense research on diluted magnetic semiconductors since twenty years ago, the origin and nature of observed ferromagnetism in these materials remain controversial, the presence of transition metal precipitates hindering to reveal unambiguously the intrinsic ferromagnetic behavior of the semiconducting matrix. In this work, we have investigated the magnetic properties of Fe-doped SiC, composed of Fe-rich nanoparticles and some diluted Fe atoms in the SiC matrix. By a careful analysis of the experimental magnetization data, a magnetic contribution from the diluted Fe atoms in the SiC matrix was evidenced, with a Curie temperature (TC) value of ∼115 K. Such a value is much higher than those reported in similar III-V diluted magnetic semiconductors such as a few at.% Mn-doped InP (TC = 20–40 K). This magnetic ordering temperature of the diluted Fe atoms is shown to be independent of the amorphous or crystalline state of the SiC matrix, but depends strongly on the Fe-rich nanoparticle size, with a drastic reduction of TC down to 45 K observed in the presence of Fe-rich nanoparticles with diameter higher than 10 nm.

Carrier-induced ferromagnetism in the insulating Mn-doped III-V semiconductor InP

Although InP and GaAs have very similar band-structure their magnetic properties appear to drastically differ. Critical temperatures in (In,Mn)P are much smaller than that of (Ga,Mn)As and scale linearly with Mn concentration. This is in contrast to the square root behaviour found in (Ga,Mn)As. Moreover the magnetization curve exhibits an unconventional shape in (In,Mn)P contrasting with the conventional one of well annealed (Ga,Mn)As. By combining several theoretical approaches, the nature of ferromagnetism in Mn doped InP is investigated. It appears that the magnetic properties are essentially controlled by the position of the Mn acceptor level. Our calculations are in excellent agreement with recent measurements for both critical temperatures and magnetizations. The results are only consistent with a Fermi level lying in an impurity band, ruling out the possibility to understand the physical properties of Mn doped InP within the valence band scenario. The quantitative success found here reveals a predictive tool of choice that should open interesting pathways to address magnetic properties in other compounds

Structural, electronic, and magnetic properties of Mn-Doped InP nanowire

In the present work, we investigate structural stability, electronic and magnetic properties of InP nanowire (NW) oriented along (111) direction and doped with Mn using first-principles calculations. Structural analysis revealed that incorporation of Mn atom in NW geometry results in strong reconstructions of surface atoms relative to core atoms. For single Mn-doped NW, partially filled d orbital of Mn atom results in magnetic semiconducting behavior due to non-degenerate electronic band-gap (∼0.1 eV). We have further considered the effect of Mn–Mn coupling on the electronic/magnetic properties of InP NW. Anti-ferromagnetic coupling state is observed as most favorable state based on total energy calculations. A half-metallic ferromagnetic coupling is also observed in case of Mn-pair doped at sub-surface of NW. The present results predict that the system doped with Mn pair between surface and core region are energetically more favorable than others.

First-Principle Investigations of Structural, Electronic, and Half-Metallic Ferromagnetic Properties in In1−xTM x P (TM = Cr, Mn)

First-principle calculations within the framework of density functional theory are employed to study the structural, electronic, and half-metallic ferromagnetic properties of In1−x (TM) x P (TM = Cr, Mn) at concentrations (x = 0.0625, 0.125, 0.25)of transition metal in zinc blende phase. The investigations of electronic and magnetic properties indicate that In1−xTM x P (TM = Cr, Mn) at x = 0.0625, 0.125, and 0.25 are half-metallic ferromagnets with 100 % magnetic spin polarization. On the one hand, the total magnetization is an integer Bohr magneton of 3 μ B and 4 μ B for In1−xCr x P and In1−xMn x P, respectively, which confirms the half-metallic feature of In1−xTM x P compounds. On the other hand, the densities of states of majority-spin states show that the large hybridization between 3p (P) and 3d (TM) partially filled states dominates the gap, which stabilizes the ferromagnetic state configuration associated with double-exchange mechanism. The band structures depict that half-metallic gap at x = 0.0625 is 0.404 eV for In1−xCr x P which is higher than 0.125 eV for In1−xMn x P. Therefore, the largest half-metallic gap in In1−xCr x P at low concentration x = 0.0625 reveals that Cr-doped InP seem to be a more potential candidate than that Mn-doped InP for spin injection applications in the field of spintronic devices.

Electronic and magnetic properties of Mn-doped InP nanowires from first principles

We have investigated, using ab initio total energy density-functional calculations, the electronic, structural, and magnetic properties of Mn doped InP nanowires. The nanowires have been constructed along the [111] direction and the dangling bonds on the surface have been saturated by hydrogen atoms. We found that the most energetically favorable position for the Mn atom is near the surface. When the Mn atoms are in ``bulklike'' positions, the magnetic Mn-Mn coupling in the nanowire is ferromagnetic. In these cases, our results are consistent with a host-$p\text{\ensuremath{-}}\mathrm{Mn}\text{\ensuremath{-}}d$ coupling mechanism. On the other hand, if at least one of the Mn atoms is located near the surface, the coupling is antiferromagnetic.

Ferromagnetic ordering in nanostructured Mn-doped InP

We report the observation of ferromagnetic ordering at 25K in a diluted magnetic semiconductor (DMS) nanoparticle system: In0.9Mn0.1P, sized 3nm. These particles were synthesized using a novel nanochemical technique without using any external surfactant. Structural and elemental characterizations established the occurrence of the zinc-blende phase of the DMS without any separate or induced impurity phase. A robust onset of ferromagnetic order is observed in magnetization measurements at around 25K with blocked state behavior below 15K characteristic of magnetic nanoparticles. The system shows strong frequency dependence of the susceptibility, similar to the behavior observed for spin glasses. Reversible transverse susceptibility experiments done using a resonant radio-frequency (rf) method reveal a strong temperature-dependent effective anisotropy.

High temperature annealing of undoped and Mn doped InP: photoluminescence and Hall measurements

Crystals of intentionally undoped n-type InP and Mn doped p-type InP were grown by the Czochralski technique. The as-grown crystals and those processed by high temperature long time annealing were studied by low temperature photoluminescence and temperature dependent Hall measurements. A new broad band was observed in those undoped InP samples which were converted to semi-insulating state by annealing. Hall measurements on those samples show that the semi-insulating state is caused by deep level defects of the same energy as the binding energy of the Fe impurity. Another new photoluminescence band appeared in the annealed InP doped with Mn, while the concentration of Mn did not change according to both photoluminescence and Hall measurements.

Evaluation of semi-insulating Ti-doped and Mn-doped InP for radiation detection

Semi-insulating and semiconducting InP single crystals without intentional doping and doped with Fe, co-doped with Zn and Ti and doped with Mn were grown using the Czochralski technique. Hall effect measurements and deep level transient spectroscopy were used to characterize samples cut from these crystals. Two electron traps were found in undoped InP whose concentration was suppressed in Mn-doped InP. Binding energies of Fe, Ti and Mn deep level impurities were determined from the temperature-dependent Hall effect measurements. The curves of Hall coefficient versus reciprocal temperature decline from straight lines at low temperatures for InP:Fe and for InP:Ti samples due to electron and hole mixed conductance. The resistivity of InP:Ti is equal to about 106 Ωm at the lowered temperature of 230 K. This value of resistivity and the small hole capture rate of Ti makes this material suitable for radiation detection at the lowered temperature.

Frequency characteristics of the Mn-doped InP p-n junction

Admittance spectroscopy is applied to the analysis of the thermal properties of the Mn acceptor-doped InP grown by liquid-phase epitaxy. The thermal activation energy and capture cross section are determined as ΔET=183 meV and σp=1.8×10−13 cm2, respectively. The cutoff frequency of the emission of holes from the Mn acceptor is 1 GHz at 300 K. It is shown that the small signal frequency characteristic of a buried heterostructure laser is improved at frequencies f&amp;gt;1 GHz by using the Mn-doped p-InP layer for the current blocking region.