Applications In Optoelectronic Devices Research Articles

Mid-Infrared, Optically Active Black Phosphorus Thin Films on Centimeter Scale.

Black phosphorus (BP) is a narrow bandgap (∼0.3 eV) semiconductor with a great potential for optoelectronic devices in the mid-infrared wavelength. However, it has been challenging to achieve a high-quality scalable BP thin film. Here we present the successful synthesis of optically active BP films on a centimeter scale. We utilize the pulsed laser deposition of amorphous red phosphorus, another allotrope of phosphorus, followed by a high-pressure treatment at ∼8 GPa to induce a phase conversion into BP crystals. The crystalline quality was improved through thermal annealing, resulting in the observation of photoluminescence emission at mid-infrared wavelengths. We demonstrate high-pressure conversion on a centimeter scale with a continuous film with a thickness of ∼18 nm using a flat-belt-type high-pressure apparatus. This synthesis procedure presents a promising route to obtain optical-quality BP films, enabling the exploration of integrated optoelectronic device applications such as light-emitting devices and mid-infrared cameras on a chip scale.

Facile sulfur-assisted synthesis of GaAs nanowires /si heterojunctions for broadband self-powered photodetector

Nanowires (NWs)-based heterojunction photodetectors (PDs) have been widely applied in the fields of remote sensing, night vision, environmental monitoring, and optical communications with high light absorption coefficient and photoelectric conversion efficiency. Here, S-GaAs NWs/Si heterojunction was developed to form a broadband self-powered PDs by growing GaAs NWs on Si substrate through the sulfur-catalyzed assisted chemical vapor deposition (CVD) technology. Compared with the pure GaAs NWs, the sulfur-assisted catalysts could not only inhibit Ostwald ripening of Au seeds to improve the crystalline quality of NWs but also form a thin Ga–S bond passivation layer to reduce surface defects and enhance the optoelectronic performance of the PDs. The fabricated GaAs NWs/Si heterojunction PDs exhibit excellent performances with the large responsivity of 10.3 mA W−1 and high detectivity of 9.59 × 1012 cm Hz1/2 W−1. Additionally, the designed PDs have the broadband wavelength photoresponse from visible to near infrared and fast response speed (rise/fall time of 3.8/21.8 ms). Importantly, the develop strategy of hybrid heterojunction PDs can be extended to other semiconductor materials for facilitating the practical application of high-performance optoelectronic devices.

Preparation and soldering performance of SAC305@Sn-bi Core-shell solder balls based on eutectic co-deposition

SnBi eutectic thin film alloys are widely used in microelectronic devices, sensors, biomedical devices due to their high resistance, low temperature coefficient, chemical stability, and biocompatibility. However, the large standard electrode potential difference (454 mV) between Sn (−0.136 V) and Bi (+0.3118 V) makes them difficult to be co-deposited, especially with eutectic composition. In this study, cathodic polarization curves were used to analyze the negative shift of the cathodic reduction potentials of Sn and Bi induced by gelatin and EDTA-2Na, respectively, which reduced the potential difference between the two to 184 mv (Sn:-0.958 v; Bi:-0.774 v) and enabled the co-deposition of Sn and Bi; cathodic overpotentials were analysed to show that catechol not only improves the degree of cathodic polarization, but also raises the overpotentials, resulting in flatter surface coatings; By adjusting the temperature, current density, and pulse current, a SnBi eutectic thin film coating with good weldability, controllable thickness, flat surface, density, and uniformity was obtained on copper foil using a platinum as the anode in a methanesulfonic acid solution. The results indicate that it is feasible to deposit SnBi solder alloy at eutectic points (Sn41.53Bi58.47, At.%). Under the synergistic effect of gelatin and unidirectional square wave pulse, a typical eutectic network morphology can be obtained, which is the same as the microstructure of industrial SnBi eutectic solder. Based on these, a core-shell composite soldering material for low-temperature soldering was obtained by using SAC305 solder balls as cores and a SnBi low-temperature soldering material coating was roll-plated on their surfaces. This study provides a reliable technical way and theoretical guidance for low-temperature soldering, preparation of low-temperature solderable core-shell composite soldering material, and application of sensors and optoelectronic devices.

Chemically derived quinary Cu2Co1–xNaxSnS4 photon absorber material and its photocatalytic application

The solar absorbing materials attract attention for the opto-electronic device applications such as solar cells and photocatalysis. Interest in photocatalytic materials to clean up the wastewater has started to increase. Generally, semiconductors sensitive to UV region are used. However, most of the light from the sun is in the visible region. Cu2CoSnS4 is a promising material that exhibits superior photo-response in the visible regions with an appropriate band gap. In this study, Cu2CoSnS4 films were prepared by the sol–gel method. Cu2Co1–xNaxSnS4 was synthesized for the first time by partly substituting sodium with cobalt. With this approach, noticeable improvements were observed in the physical properties of the material. With the sodium replacement, the Cu2Co1–xNaxSnS4 exhibited high photocatalytic performance toward the degradation of methylene blue (MB) under visible-light irradiation. According to the results, Cu2CoSnS4 and Cu2Co1–xNaxSnS4 samples degraded the MB solution by degradation efficacy values of 89.69% and 94.57%, respectively, in a short time like 40 min under visible light. This study shows that the substitution of sodium boosted the degradation efficiency by 5.4%. For the Cu2CoSnS4 and Cu2Co1–xNaxSnS4 samples, the computed reaction rate constants are 0.059 min−1 and 0.077 min−1, respectively.

A systematic first-principles investigation of the structural, electronic, optical, thermodynamic and transport properties of lead-free pyrochlore oxides Q2Sb2O7 (Q= Be, Ca, Sr) for low-Cost energy applications

A systematic study has been performed on structural, optical and thermophysical properties of newly designed pyrochlore oxides Q2Sb2O7 (Q = Be, Ca, Sr) employing FP-LAPW based first-principles calculations. The GGA approach was used to treat exchange and correlation potentials. The investigated E-V plots reveals that Sr2Sb2O7 is the most stable structure compared to Be2Sb2O7/Ca2Sb2O7. A direct energy bandgap of 0.29 eV is evident from band structure plot of Be2Sb2O7, however, Ca2Sb2O7/Sr2Sb2O7 possess indirect energy bandgaps of magnitude 1.47/1.467 eV. The studied materials show maximum absorption of incoming photons in near UV region as shown in ε2(ω) plots, however, considerable absorption in visible region is also present. Ca2Sb2O7/Sr2Sb2O7 are effective optical material with a n(ω) value between 1.0 and 2.0. Optical properties of pyrochlore oxides reveal that these materials are potential candidates for shielding materials in upper UV region. A photon reflection of up to 60% is evident from the R(ω) in UV region, however, in IR and visible regions, the reflectance is negligible. Based on calculated values of Seebeck coefficient (S), we can state that Be2Sb2O7 is n-type semiconductor whereas Ca2Sb2O7/Sr2Sb2O7 are p-type semiconductors. The most effective thermoelectric material among Q2Sb2O7 (Q = Be, Ca, Sr) is Ca2Sb2O7 as its ZT value is highest (∼1.05) in the entire temperature range. Thermodynamic properties of Q2Sb2O7 (Q = Be, Ca, Sr) are also evaluated to check dynamical stability and appropriateness of these materials in thermal applications. The investigated outcomes show that these pyrochlore oxides are potential candidates for thermoelectric and optoelectronic device applications.

Raman scattering evolution in temperature-induced ferroelectric phase transition of few-layer NbOCl2

NbOCl2 is an emerging layered ferroelectric (FE) material with unique photoelectric properties. However, the phonons and thermal properties of NbOCl2 have remained elusive. Here, we report measurements of Raman and second harmonic generation spectrum of NbOCl2 flakes as a function of temperature (80–500 K). All observed Raman modes exhibit temperature-dependent shift. The first-order temperature coefficients of P1, P2, P3, P4, and P5 modes are 0.001 58, −0.005 21, −0.006 44, −0.012 56, and 0.036 75 cm−1 K−1, respectively. Interestingly, the frequency of the P1 mode changes directly from 161 to 156 cm−1 with increasing temperature, which is attributed to the switching between two independent Raman modes (P1H and P1L). The P1H mode is mainly contributed by the FE phase, while the P1L mode is mainly contributed by the antiferroelectric phase. Our results provide a fundamental understanding and analysis of the thermal–phonon coupling properties of few-layer NbOCl2 and promote the deep exploration of the basic physical properties of few-layer NbOCl2, which is crucial for the design and application of NbOCl2-based thermal and optoelectronic devices in the future.

Theoretical prediction (DFT) and experimental observation of electronic and electro-optical properties of HATn (n = 5,6,7,8) molecules for optoelectronic applications

The formation of triphenylene core-based discotic mesogens exhibiting a classical columnar phase led to several superior electronic and optoelectronic applications. The present work reports the theoretical investigation of discotic hexaalkoxytriphenylene (HATn; n = 5, 6, 7, 8) mesogens including electro-optical, electronic, and thermodynamic properties using density functional theory (DFT) as a computational quantum mechanical tool. The various physical and chemical properties of these mesogens, such as electronegativity, specific heat capacity, polarizability, absorption, and dipole moment are calculated computationally and discussed in the study. The simulation study reveals the variation in physical properties either follows the odd–even effect or changes monotonically for HATn series. Experiment has been performed for comparison with the theoretical results. The physical and chemical properties of these discotic mesogens change with alkyl chain length variation and explain the structure–property correlation in the molecules. The obtained results of the designed molecular structure held promising applications for optoelectronic devices based on discotic mesogens.

Orientation Dependent Interlayer Coupling in Organic–Inorganic Heterostructures

AbstractOrganic–inorganic 2D heterostructures combine the high optical absorption of organic molecules with exciton‐dominated optical properties in layered transition metal dichalcogenides (TMDs) such as MoS2. Critical to the interaction and the optical response in such hybrid systems is the electronic band alignment at the interface between the two species. Here, the coupling of monolayers of perylene derivatives is investigated with bilayer MoS2. In particular, variation in the perylene orientation on the MoS2 surface is identified using Raman spectroscopy and scanning probe microscopy. Low‐temperature optical spectroscopy reveals orientation‐dependent interlayer exciton formation. Furthermore, power‐dependent photoluminescence measurements provide insight into the modified interlayer charge transfer in these heterostructures. A saturation of interlayer states is found under high excitation power when the perylene molecules are in a perpendicular orientation to the surface that leads to electron accumulation in the MoS2, whereas parallel alignment of the perylene molecules leads to enhanced populations of organic–inorganic interlayer excitons. This work provides insights into the optimization of organic–inorganic heterostructures, with particular relevance to applications for optoelectronic and excitonic devices.

All-Perovskite Multicomponent Nanocrystal Superlattices.

Nanocrystal superlattices (NC SLs) have long been sought as promising metamaterials, with nanoscale-engineered properties arising from collective and synergistic effects among the constituent building blocks. Lead halide perovskite (LHP) NCs come across as outstanding candidates for SL design, as they demonstrate collective light emission, known as superfluorescence, in single- and multicomponent SLs. Thus far, LHP NCs have only been assembled in single-component SLs or coassembled with dielectric NC building blocks acting solely as spacers between luminescent NCs. Here, we report the formation of multicomponent LHP NC-only SLs, i.e., using only CsPbBr3 NCs of different sizes as building blocks. The structural diversity of the obtained SLs encompasses the ABO6, ABO3, and NaCl structure types, all of which contain orientationally and positionally locked NCs. For the selected model system, the ABO6-type SL, we observed efficient NC coupling and Förster-like energy transfer from strongly confined 5.3 nm CsPbBr3 NCs to weakly confined 17.6 nm CsPbBr3 NCs, along with characteristic superfluorescence features at cryogenic temperatures. Spatiotemporal exciton dynamics measurements reveal that binary SLs exhibit enhanced exciton diffusivity compared to single-component NC assemblies across the entire temperature range (from 5 to 298 K). The observed coherent and incoherent NC coupling and controllable excitonic transport within the solid NC SLs hold promise for applications in quantum optoelectronic devices.

Study of absorption and emission spectra of substituted terthiophene compounds by methods of theoretical chemistry.

Terthiophene derivatives attract interest due to their prospective applications in optoelectronic or sensor devices. Due to their nontoxicity they can be considered as suitable candidates in biological applications. Supramolecular organization of the matter is one of the most interesting topics in contemporary materials science. Amphiphilic chromophores based on substituted terthiophenes are capable of self-assembly into supramolecular architectures. In this work, we aim at simulation of the spectral properties of terthiophene with oligo(ethylene oxide) substituents by the methods of quantum chemistry and molecular dynamics (MD). The potential energy surface (PES) of this molecule was determined by the methods of density functional theory (DFT) for the ground state and time-dependent density-functional theory (TD-DFT) for the excited state. MD simulations in water than revealed the most frequented molecular conformations in both these states. Absorption and fluorescence spectra were determined for all these conformations, including the surrounding water molecules, using TD-DFT and averaged over the conformation space to obtain the final absorption and fluorescence spectrum. The calculated spectra were compared with their experimental counterparts and the differences were discussed in context of the supramolecular structure revealed by confocal microscopy. In spite of its simplicity, this approach provides a satisfactory approximation of absorption and fluorescent spectra of these molecules obtained by computational methods.

Evaluating the optoelectronic properties of individual CsPbBr3 microcrystals by electric AFM techniques

All-inorganic perovskite materials are attracting the attention of researchers owing to the good performance that they exhibit in optoelectronic device applications. In particular, cesium lead halide single crystals are of interest for their electric conductivity. However, the conductive properties of these materials are still far from being fully understood. In this work, we used several scanning probe microscopy techniques to investigate different properties of CsPbBr3 single crystals, namely their topography, electric conductivity, electric surface potential and ferroelectricity. We observed heterogeneity in conductance and work function of the different facets by using conductive atomic force microscopy and Kelvin probe force microscopy measurements. Additionally, piezo-response force microscopy was carried out to gain insight on the origin of the hysteresis in our microcrystals. Our results show the absence of ferroelectric domains and we attribute the I–V hysteresis to ionic migration within the crystal.

Electronic, direct optical, and phonon-assisted optical properties of 4H Si from first principles

The cubic polytype of silicon (Si) is the most commercialized semiconductor material and finds applications in numerous electronic and optoelectronic devices, such as solar cells. However, recent reports on the synthesis of the hexagonal 4H Si polytype have attracted the attention of the scientific community to understand its functional properties. Here, we report the electronic, vibrational, and optical properties of the 4H Si polytype obtained with predictive first-principles calculations, with an emphasis of phonon-assisted absorption in the indirect regime. Compared to the cubic polytype, 4H Si shows a slightly narrower indirect gap by ∼0.05 eV. The calculated phonon-assisted optical spectra show that 4H Si exhibits a stronger absorption coefficient than cubic Si across the visible and IR spectral regions. We further evaluate the short-circuit current density of textured thin-films. We demonstrate that 4H Si can achieve the same short-circuit current density for a five times thinner film compared to the cubic polytype, which mainly resulted from absorption in the indirect gap regime. Our work demonstrates the advantages of 4H Si for thin-film silicon-based solar-cell applications.

Theoretical studies on phase stability, electronic, optical, mechanical and thermal properties of chalcopyrite semiconductors HgXN2 (X=Si, Ge and sn): A comprehensive DFT analysis

In this study, the ground state physical properties of Hg-based chalcopyrite semiconductors, HgXN2 (X = Si, Ge and Sn), are investigated using the density functional theory (DFT), which is based on full potential linearized augmented plane wave (FP-LAPW) method. The structural, electronic, optical, mechanical and thermal properties of the body-centered tetragonal (BTC) phase, HgXN2 (X = Si, Ge and Sn), have been calculated using the modified Becke-Johnson exchange-correlation potential (TB-mBJ). The obtained lattice parameters and volume are in good agreement with the values reported earlier, indicating that the results are reliable and reproducible. The phase stability of the titled compounds is elaborately studied and it is confirmed that all are thermodynamically, dynamically and mechanically stable. The electronic band structure demonstrated a direct band gap of 1.70 eV, 0.99 eV, and 0.94 eV for the HgXN2 (X = Si, Ge and Sn) compounds, respectively. Both HgGeN2 and HgSnN2 compounds have a notably lighter carrier effective mass, resulting in higher carrier mobility and conductivity than HgSiN2. The order of the mechanical hardness is as follows: HgSiN2> HgGeN2> HgSnN2. The studied materials are also anisotropic in mechanically and optically. All the title compounds exhibit ductile behavior. The charge density contour plots indicates the dominant covalent nature of the bonds in HgXN2 (X = Si, Ge and Sn). All these compounds have a high absorption coefficient and low optical reflectivity in the visible light range. Due to the favorable band gap and high absorption coefficient, these compounds could be suitable for optoelectronic or photovoltaic device applications. Moreover, the thermal expansion coefficient, thermal conductivity, melting point and fracture toughness behavior have been calculated, which also showed promise for thermal barrier coating (TBC) applications.

Improved optical and electrical response by glancing angle synthesized Al2O3 nanorod array device

An Aluminum Oxide (Al2O3) nanorod (NR) array–based device has been synthesized upon an Al2O3 thin film (TF) by electron beam (E-beam) evaporation with a glancing angle deposition technique. The complete fabrication has been done inside a vacuum coating unit. The Al2O3 nanostructures have been fabricated on a silicon substrate. Field emission scanning electron microscopy and transmission electron microscopy show a vertically aligned Al2O3 NR array. From the Tauc plot, the optical band energies are estimated as 5 eV and 5.5 eV for the bare Al2O3 TF and Al2O3 NR/Al2O3 TF devices, respectively. Significant improvement has been observed in photosensitivity by 10 fold, detectivity by 4.2 fold, and noise equivalent power (NEP) by 16.5 fold for the Al2O3 NR/Al2O3 TF device compared with the Al2O3 TF. The Al2O3 NR/Al2O3 TF device exhibits a very fast photoswitching response (rise time = 0.15 s and fall time = 0.13 s). Therefore, the Al2O3 NR/Al2O3 TF device proves to be a prominent candidate for next-generation optoelectronic device applications.

Phase-sensitive large Kerr nonlinearity in semiconductor quantum wells

This paper presents a comprehensive investigation on Kerr nonlinearity in a three-level semiconductor quantum well (SQW) superlattice and validates the existence of large Kerr nonlinearity of the order of [Formula: see text] in the vicinity of an electromagnetically induced transparency (EIT) window. The Kerr nonlinearity is found to vary with the relative phase of the applied optical fields, and by selecting suitable relative phases, an enhanced Kerr nonlinearity can be obtained. The results may find significant applications in optoelectronic and photonic devices.

Unveiling structural and optical properties of Sn-doped β-Ga2O3: A correlation of experimental and theoretical observations

This work presents the experimental and theoretical insights into the structural and optical properties of tin (Sn)-doped β-Ga2O3. Sn-doped β-Ga2O3 films were fabricated using the low-pressure chemical vapor deposition (LPCVD) method onto the c-plane sapphire substrate. Further, deposited thin films were characterized for their structural and optical properties. XRD pattern depicts the crystalline nature of β-Ga2O3. The energy band gap (Eg) obtained from UV–Vis spectra has been decreased from 4.82 eV to 4.77 eV for as-deposited β-Ga2O3 to Sn-doped β-Ga2O3, respectively. However, an increase in absorbance has been observed in Sn-doped β-Ga2O3 films. Further, the first principle study based on density functional theory (DFT) has been used to comprehend the effect of Sn doping in β-Ga2O3 films. DFT result reveals the expansion of the lattice parameter of intrinsic β-Ga2O3 on the introduction of the Sn atom. Furthermore, a reduction in Eg has been observed upon Sn doping into the β-Ga2O3 structure similar to the experimental results. The reason behind the reduction in the Eg may be due to the Sn-5s energy level at the bottom of the conduction band as revealed in density of state (DOS) investigations. Also, the DOS results of Sn-doped β-Ga2O3 suggest that the atom has tended to form the ionic bond characteristics with the introduction of Sn into the β-Ga2O3, where the free electrons of the Sn-5s orbital state will fill the conduction band and may improve the conductivity. Additionally, optical properties such as reflectance and dielectric loss of function have been investigated. The reflectance and dielectric loss of function result proposed that more energy was absorbed when Sn was introduced to β-Ga2O3. Therefore, our observation suggests that upon Sn doping into β-Ga2O3, optical as well as structural properties were improved and these improved properties may be useful for optoelectronic devices.Novelty statementβ-Ga2O3 is an emerging material for optoelectronic device applications due to its excellent wide energy band gap, high critical electric field strength, high melting point, high Baliga figure of merits (BFOM), and exceptional physical and chemical stability. However, intrinsic β-Ga2O3 suffers from poor mobility and surface defects. Therefore, β-Ga2O3 needs a dopant material to enhance its' structural and optical properties. In this case, Sn doping may improve the optoelectronic properties of β-Ga2O3. Therefore, detailed theoretical and experimental investigations on Sn-doped β-Ga2O3 become necessary to understand inside phenomena. However, lots of experimental and theoretical works have been performed on Sn-doped β-Ga2O3. But, to date, there is no available report related to the correlation of theoretical and experimental data-based studies on Sn-doped β-Ga2O3. In this work, we have explored the structural and optical properties of Sn-doped β-Ga2O3 thin films deposited by the LPCVD method on the c-plane sapphire substrate. Further, the experimental results obtained were correlated with the first principal based DFT results. Our observation suggests that upon Sn doping into β-Ga2O3, optical as well as structural properties were improved and these improved properties may be useful for optoelectronic devices.

A new candidate for optoelectronic device applications: CoTiX (X: P, As, Sb) half-heusler compounds

Some theoretical calculations of CoTiX(X:P, As, Sb) Half-Heusler(HH) compounds in MgAgAs-type structure have been analyzed using density functional theory (DFT). These Half-Heusler compounds are stable mechanically, and CoTiAs are entirely isotropic, whereas CoTiP and CoTiSb are anisotropic. Mechanical properties indicate that they have a ductile nature in all three compounds. In addition, elastic properties are presented in three dimensions (3D) for detailed analysis of Young's modulus, linear compressibility, shear modulus, and Poisson's ratio. Electronically, the investigated compounds are semiconductors with an indirect bandgap. The calculated positive phonon vibration frequencies of these Half-Heusler compounds show their dynamic stability in the cubic MgAgAs phase. Optical parameters such as dielectric function, reflectivity, absorption coefficient, refractive index, loss function, and absorption coefficient are given in IR, visible, and ultraviolet regions according to considerable photon energies. Finally, the effects of pressure and temperature on thermodynamic properties are discussed in detail.

Effect of substrate on structural and transport properties of La0.05Sr0.95SnO3 and La0.05Ba0.95SnO3 epitaxial films

Perovskite-structured stannate La0.05Sr0.95SnO3 and La0.05Ba0.95SnO3 films were deposited on SrTiO3, LaAlO3, LSAT, PMN-PT, and MgO substrates using pulsed laser deposition, respectively. The effects of substrates on the structure, transport properties, and optical properties of the films were investigated in detail. High-resolution X-ray diffraction results revealed the epitaxial growth of all films on each substrate without any impurity phase, and a high lattice quality indicated by the rocking curves. Atomic force microscopy images confirmed the low root-mean-square roughness observed in all films. Hall effect measurements showed that the maximum mobility was obtained for both La0.05Sr0.95SnO3 films and La0.05Ba0.95SnO3 films grown on SrTiO3 substrates, with values of 26.46 cm2/Vs and 43.09 cm2/Vs, respectively. The temperature dependence of resistivity at low temperatures was attributed to e−-e− interactions. Optical transmittance spectra showed high transparency of all films in both visible and near-infrared regions. Collectively, these results indicate that La-doped SrSnO3 and BaSnO3 films exhibit excellent performance across various substrates, providing a wide range of options for optoelectronic device applications.

Exploring the Influence of Solvents on Electrochemically Etched Porous Silicon Based on Photoluminescence and Surface Morphology Analysis.

Porous silicon (PSi) has promising applications in optoelectronic devices due to its efficient photoluminescence (PL). This study systematically investigates the effects of various organic solvents and their concentrations during electrochemical etching on the resulting PL and surface morphology of PSi. Ethanol, n-butanol, ethylene glycol (EG) and N,N-dimethylformamide (DMF) were employed as solvents in hydrofluoric acid (HF)-based silicon etching. The PL peak position exhibited progressive blue-shifting with increasing ethanol and EG concentrations, accompanied by reductions in the secondary peak intensity and emission linewidth. Comparatively, changes in n-butanol concentration only slightly impacted the main PL peak position. Additionally, distinct morphological transitions were observed for different solvents, with ethanol and n-butanol facilitating uniform single-layer porous structures at higher concentrations in contrast to the excessive etching caused by EG and DMF resulting in PL quenching. These results highlight the complex interdependencies between solvent parameters such as polarity, volatility and viscosity in modulating PSi properties through their influence on surface wetting, diffusion and etching kinetics. The findings provide meaningful guidelines for selecting suitable solvent conditions to tune PSi characteristics for optimized device performance.

(Ga,Mn)N—Epitaxial growth, structural, and magnetic characterization—Tutorial

The spin control possibility and its application in optoelectronic devices began an intensive research into its utilization, in particular, in the wide-gap semiconductors such as GaN doped with transition metal ions. Due to a strong p–d hybridization in Ga1−xMnxN, the Curie temperature above 300 K was already expected for x = 5%, providing that the free hole concentration necessary for the hole-mediated ferromagnetism exceeds 1020 cm−3. In this context, the development of non-equilibrium techniques enabled the engineering high-quality epitaxial layers of (Ga,Mn)N exhibiting uniform ferromagnetism at low-end cryogenic temperatures. The Tutorial is focused on the molecular beam epitaxy growth method of the Mn-enriched GaN magnetic semiconductors, summarizes the (Ga,Mn)N structural and electronic studies, and explains fundamental ferromagnetic properties, including the determination of the Mn concentration and the Curie temperature based on magnetic measurements. Most studies reveal the homogenous substitution of Mn3+ ions in the GaN matrix. Nevertheless, achieving room-temperature ferromagnetism still remains a challenge. Therefore, in the Tutorial, future research is suggested that can help obtain the homogenous ferromagnetism in (Ga,Mn)N at much elevated temperatures.