It is difficult to grow Mg-doped GaN epilayer (Mg:GaN) with high hole concentration ( 1E18 cm⁻³) to fabricate p-type contact on laser diodes and light emitting devices due to high ionization energy ( 200 meV) along with issues like passivation, compensation, segregation etc. High temperature post-growth activation of Mg may generate holes but adversely affect the material and electrical characteristics due to creation of donor-like nitrogen vacancy defects. Post-growth rapid thermal annealing (RTA) has been optimized for activation of Mg dopants in metal organic vapor phase epitaxy (MOVPE) grown Mg:GaN epilayers to enhance hole concentration with minimal deterioration in material characteristics. Effect of RTA temperature (800–900 °C) on the crystalline quality, morphology, optical quality and Mg distribution in GaN has been studied systematically using high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), photoluminescence (PL), and secondary ion mass spectroscopy (SIMS), respectively. Electrochemical capacitance voltage (ECV) measurement has been presented as a convenient and reliable technique to depth profile the hole concentration and ascertain extent of activation. Activation of more than 6

In this investigation, novel PVDF-metal oxide (MO) nanocomposite-based systems were meticulously developed and thoroughly characterised. Employing an eco-friendly green synthesis process, a polymer-metal oxide nanocomposite system was successfully constructed using two distinct nanoparticles. The integration of nanocomposite systems was accomplished using the versatile sol–gel technology, and an innovative spin coating method was utilised to create the nanocomposite thin films without requiring an electrical field or a post-processing poling step. The characterisation encompassing morphology, structural, electrical, and piezoelectric performance was conducted. Notably, all PVDF/MO nanocomposite thin films surpassed the individual PVDF thin film in piezoelectric performance, demonstrating their exceptional potential. Among them, the PVDF nanocomposite doped with ZnO and TiO2 exhibited the most promising and superior piezoelectric performance. The outstanding piezoelectric capabilities displayed by The PVDF/MO nanocomposite systems offer remarkable potential for their utilization as an innovative energy source in nanogenerators, making them an enthralling option for future applications.

Silicon based conventional solar cells have dominated the photovoltaic (PV) market as they have high efficiency even though their production cost is comparatively high. Continuous efforts for an alternative to the conventional cells have been made across the globe to reduce the cost. One of the most standout in the search of an alternative is the hybrid solar cells – a blend of both organic and inorganic materials. Organic materials are keenly priced, easy to process and their functionality can be altered by chemical synthesis and molecular engineering. Inorganic semiconductors have high absorption coefficients, by possibility of varying size of nanoparticles the absorption range can be tailored with tunability of band gap. Hybrid halide perovskites possess quite interesting properties such as large absorption coefficients, high carrier mobility, long carrier life time, long carrier diffusion length and a tunable energy band gap. These properties have attracted more attention for optoelectronic applications, especially in photovoltaic devices. The evolution of perovskite solar cells (PSCs) towards a formidable performance would depend on its synthesis techniques. In this book chapter, we present the various methods used in the synthesis of single crystals of hybrid perovskites and address the main synthesis issues pertaining to PSCs.

Yttrium (1 mol %) -doped 0.49BiFeO(3)-0.20Pb(Mg1/3Nb2/3)O-3-0.31PbTiO(3) ceramic at the morphotropic phase boundary was synthesized by a solid-state reaction via columbite precursor technique. X-ray diffraction (XRD) and FESEM analysis confirmed a perovskite phase in the P1m1 space group with a homogeneous microstructure sintered at 920 degrees C. Rietveld refinement yield lattice parameters a = 3.95984 angstrom, b = 3.93828 angstrom, c = 4.04466 angstrom, alpha = 90.000 degrees, beta = 89.970 degrees, gamma = 90.000 degrees. Studies of dielectric permittivity and ferroelectric hysteresis at room temperature shows Y doping impact, exhibiting low dielectric loss and a saturated hysteresis loop. The synthesized sample remains fatigue-free over 10(4) cycles, with a high value of converse piezoelectric coefficient of d(33)* similar to 723 pm/V. Weak ferromagnetism is observed in the magnetic hysteresis loop (M-H) at room temperature, suggesting potential applications in ferroelectric-based technologies.

Pure and Mn-doped 0.49BiFeO 3 –0.20Pb(Mg 1/3 Nb 2/3 )O 3 –0.31PbTiO 3 (BF–PMN–PT) ceramics at morphotropic phase boundary (MPB) have been prepared by solid state reaction method. A systematic investigation of its microstructure and electrical properties was conducted. Powder X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM) showed the formation of pure perovskite phase with homogeneous microstructure having average grain size of 2.48 µm at optimum temperature 920 °C. As compared to the pure BF–PMN–PT ceramic, enhanced dielectric constant value (~ 800) was observed for Mn-doped sample at room temperature. Polarization vs. electric field (P–E) hysteresis curves exhibits improved ferroelectric properties (P r = 97.65 C/cm 2 at coercive field E c = − 17.08 kV/cm) after doping and showed a fatigue free nature over 10 4 switching cycles. The displacement voltage (D–V) curve showed a high value of the piezoelectric coefficient d 33 * = 786 pm/V after Mn doping. The magnetic hysteresis loop (M–H) curve showed a weak ferromagnetic nature with coercive field (H c = 54.19 Oe) and remanent magnetization (M r = 0.0087 emu/g) of the sample. Therefore, Mn-doped BF–PMN–PT ceramic can be a promising candidate for applications in the electronic ceramic industries.

A near-morphotropic phase boundary (MPB) composition of ternary 0.49BiFeO 3 -0.20Pb(Mg 1/3 Nb 2/3 )O 3 -0.31PbTiO 3 (BF-PMN-PT) ceramic was synthesized for various dielectric, ferroelectric and piezoelectric applications using the conventional solid-state reaction method via a two-step columbite precursor technique. Powder x-ray diffraction (XRD) confirms the perovskite phase of the synthesized ceramic with a monoclinic crystal structure belonging to the P1m1 space group. The dielectric properties and the relaxation mechanisms of this ternary ceramic were studied using dielectric spectroscopy measurements for the frequency range of 10 Hz to 1 MHz over a wide range of temperature from 50°C to 400°C. A good dielectric response was observed with a high dielectric constant value (~ 800) that decreases with increasing frequency. A phase transition temperature ( T c = 275°C) and a low dielectric loss were also observed. The dielectric exhibits a clear and distinct Debye-type relaxation in the ferroelectric phase. The measured dielectric data fit quite well with the modified Debye model. Various Debye fitting parameters were obtained which show a temperature-dependent nature. The value of Debye broadening parameter α exhibits a decreasing trend from 0.136 to 0.003 as temperature increases from 50°C to 200°C, after which it increases and attains a maximum value of 0.566 at 350°C . The Cole–Cole plot obtained from the measured data reveals the distributive nature of the sample’s dielectric relaxation.

The thickness of dielectric spacer layer (DSL) plays an important role in performance of plasmonic solar cells. In this work, effect of thickness variation of ITO (indium tin oxide) DSL in silver (Ag) nanospheres/ITO/crystalline silicon(c-Si) structure on forward and backward scattering efficiencies has been investigated. Simulations were carried out using the open-source software MEEP via FDTD method for Ag nanospheres of sizes 50nm, 80nm and 100nm. Maximum forward scattering was observed with 80nm thickness of ITO DSL for all sizes of Ag nanospheres. Transmittance at ITO/c-Si interface and spatial distribution of electric field have been investigated for optimised thickness of ITO DSL. In visible to near infra-red region, maximum transmittance was exhibited by 100nm Ag nanosphere. Enhanced electric field has been observed with increasing size of nanosphere. This study provides us an optimum value of ITO DSL thickness in Ag nanospheres/ITO/c-Si structure to fabricate a photovoltaic device with upgraded efficiency.

A ternary 0.49BF-0.20PMN-0.31PT ceramic with composition at morphotropic phase boundary has been synthesized using the solid-state reaction method. The perovskite phase of synthesized 0.49BF-0.20PMN-0.31PT ceramic with monoclinic structure was confirmed by powder XRD. Dense microstructure with uniform grain was revealed by the FESEM micrograph. An excellent dielectric response with a high dielectric constant value, high-phase transition temperature (Tc = 275 °C) and low dielectric loss was obtained. A large value of piezoelectric coefficient (d33* = 632 pm/V) was achieved from the butterfly loop. The pyroelectric study revealed an excellent pyroelectric response for the ceramic. BF-PMN-PT ceramic displayed excellent ferroelectric P-E hysteresis loops with good fatigue resistance. The magnetic hysteresis loop (M-H) was traced at room temperature which displayed weak ferromagnetic nature of the sample. The obtained properties of the synthesized MPB composition of BF-PMN-PT indicate its great potential in ferroelectric device applications.

In this work, two different geometries of Au core-Al2O3 shell composite nanospheres (CNS) in ITO/a-Si:H based solar cell structure have been considered. A finite-difference time domain (FDTD) analysis of optical and electrical properties for both geometries has been conducted using open-source software MEEP. When embedded in the active layer of the cell, Au core-Al2O3 shell CNS exhibit relatively high scattering efficiency over a broad spectrum. Maximum normalized scattering efficiency for ‘CNS on top’ geometry has been found 18.16 while that for ‘embedded CNS’ geometry it boosts up to 19.62. The localized surface plasmon resonance wavelength achieves a value of 738.9nm for ‘CNS on top’ and 835.8nm for ‘embedded CNS’ configurations. Furthermore, reflectance of the incident radiation reduces significantly with the shell thickness leading to effective light trapping. This study provides an important design to enhance the efficiency of silicon based plasmonic solar cells.

In this paper, the impact of pyramidal texture on a silicon substrate in ZnO/p-Si heterojunction was investigated. The texturisation of p-type silicon (100) substrate was obtained using the KOH anisotropic wet chemical etching method for different etching times. The RF magnetron sputtering technique was used to deposit ZnO thin films on textured Si substrates and planar Si substrates to form ZnO/Si heterojunction. The surface morphology was studied with field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Optical properties were investigated using UV-Visible spectroscopy and photoluminescence (PL). The results show that the PL intensity in the visible region of the electromagnetic spectrum increases with the etching time, while a significant reduction is observed in the reflectance. Due to impressive anti-reflection response, ZnO/Si (textured silicon-TS) heterojunction can be effective in improving the efficiency of solar cells.

In this paper, thin film of ZnO nanoparticles deposited on a planar Si (100) and a textured Si (100) substrate are investigated. Chemical etching is used to prepare textured Si substrate and RF magnetron sputtering is used to deposite ZnO thin films. The surface morphology and reflectance are studied with SEM and UV-VIS Spectroscopy, respectively. Structural morphology of the etched wafer indicate random pyramidal structures. Optical study indicates a significant reduction in reflectance for textured silicon (TS) heterojunction in comparison to planar Si (PS) heterojunction. This study promotes the study of heterojunction devices and surface texturing for light management in various optoelectronic devices.

We have demonstrated the impact of fabrication of pyramidal structure on Silicon (Si) wafer substrate in ZnO/Si heterojunction on its structural and optical properties. The texture on Si substrate is obtained using wet etching method for different time durations. Patterns of photoresist have been used to get desired size of the structure. Scanning electron microscopy (SEM) of the samples shows a pyramidal structure on the surface of Si substrate. The thin film of ZnO material on p-type planar silicon (100) and textured Si (100) substrate has been deposited by using RF magnetron sputtering technique. ZnO thin films produce an anti reflection (AR) effect when deposited on silicon substrate. The structural and optical properties of ZnO/Si (TS) heterojunction were studied by x-ray diffraction (XRD) and UV-Vis spectrophotometer respectively. XRD patterns of the ZnO/Si and ZnO/Si (TS) heterojunctions show the orientation of the ZnO film fabricated on silicon substrate. Their reflectance spectra show reduction in reflectance proportional to increase in time duration of texturization. This study indicates that ZnO/Si (TS) heterojunction may be utilized in various heterojunction and photovoltaic devices for reduction in reflection of incident light.

In this paper the crystalline and morphological properties of Pd thin films deposited on glass substrate by pulsed laser deposition (PLD) technique at different substrate temperatures have been investigated. These films were deposited with an excimer (XeCl) laser source (lambda= 308 nm, pulse duration of 30 ns, repetition rate of 10 Hz). The fabricated films were characterized by various methods such as X-ray diffraction (XRD) and atomic force microscopy (AFM). The thickness and refractive index of samples were measured using ellipsometry. There was influence of substrate temperature on the surface roughness of thin film. The rms roughness increases with increasing temperature. As the temperature increase the crystallinity of the film also increases.

In this paper the structure, morphology and optical properties of Pd thin films deposited on glass substrate by pulse laser deposition technique at two different substrate temperatures have been investigated. The fabricated films were characterized by various methods such as XRD, AFM, and UV–vis-NIR spectroscopy. The influence of surface roughness and angle of incidence with p polarization was investigated experimentally by optical property of palladium (Pd) thin films of two different thicknesses and rms roughness from transmission measurement in the visible spectral range. It has been shown that the experimental transmittance spectra agree well with their theoretical values for absorbing Pd thin film. The transmittance of thin film increases with increase in incident angle for the same sample.

This work describes a homogeneous single layer model for surface roughness by polarized light. It has been shown that the reflectance change in non-absorbing layer is directly proportional to the refractive index of the ambient and substrate media for s polarization but inversely proportional to the p polarization and it is directly proportional to the square of the thickness of the layer for both the polarization. The thickness of the film has been written in terms of surface roughness to correlate the homogeneous model with the scattering theory. The consequence of the scattered light on the specular reflectance and transmittance for oblique incidence shows that there is reduction in reflectance and transmittance, due to roughness on the surface under the Drude effective-medium approximation.

In this paper a homogeneous single layer model for surface roughness by polarized light has been developed. It has been shown that the reflectance change in non-absorbing layer is directly proportional to the refractive index of the ambient and substrate media for s polarization but inversely proportional to the p polarization and it is directly proportional to the square of the thickness of the layer for both the polarization. In an absorbing layer, it has been shown that the thickness of the layer is equal to the twice of surface roughness of the single layer identical system for s polarization but it is ratio of twice of surface roughness to the square of refractive index of thin film for p polarization. The extinction coefficient of the layer is directly proportional to the thickness of that layer for both the polarization. The consequence of the scattered light on the specular reflectance and transmittance for oblique incidence shows that there is reduction in reflectance (in both non-absorbing and absorbing cases) and transmittance (in the absorbing case for p polarization only), due to roughness on the surface under the Drude effective-medium approximation. Thus such an absorbing layer provides a valid model for the effect of scatter on the transmittance for p polarization only.

In this paper a homogeneous model for surface roughness in the identical double layer system has been presented. It has been shown that the reflectance change in non-absorbing layers is directly proportional to the square of the total thickness of the layers. In an absorbing layer, it has been shown that the thickness of each layer is equal to the surface roughness of the identical double layer system. The extinction coefficients of both layers are directly proportional to the thickness of that layer.

In this paper homogeneous model for surface roughness in identical layer system has been presented. It has been shown that reflectance change in non-absorbing layer is directly proportional to the square of total thickness of the layers. The reflectance in the visible range of the wavelength changes (decreases) substantially when the roughness factor or the number of layers are increases. In the present model the reflectance of the double layer system can be explained with the help of only one parameter that is roughness factor sigma.