Lower Crystalline Quality Research Articles

Recent Progress of Thin Crystal Engineering for Perovskite Solar Cells.

Metal halide perovskite single crystals hold promise for photovoltaics with high efficiency and stability due to their superior optoelectronic properties and weak bulk ion migration. The past several years have witnessed rapid development of single-crystal perovskite solar cells (PSCs) with efficiency rocketed from 6.5 % to 24.3 %, however, which still lags behind their polycrystalline counterparts. Moreover, the poor device stability under light illumination is contrary to the high ion migration barrier of perovskite single crystals. The key limiting factors should be the low crystalline quality and high surface defect density of solution-grown thin single crystals. Under this circumstance, a review paper summarizing the recent progress and challenges will be instructive for future development of this emerging field. In this manuscript, the crystal engineering used to enhance carrier transport and suppress carrier recombination in vertical single-crystal PSCs will be summarized initially, including crystal growth, component control, surface and interface modification. Subsequently, the application of perovskite single crystals in lateral single-crystal PSCs will be discussed and compared with the conventionally vertical structure. Finally, the challenges and proposed strategies for the development of single-crystal PSCs are provided.

Extraction and Physicochemical Characterization of Hydroxyapatites From Horse Humerus Bones of Different Ages (1, 3, 6, and 8 Years old) Calcined at Low Temperature.

The aim of this work is to investigate the changes in the physicochemical properties of hydroxyapatite (HAp) extracted from horse humerus bones of different ages (1, 3, 6, and 8 years) subjected to low temperature calcination (600°C). Thermal analysis revealed significant mass loss due to water, collagen, organic compounds, carbonates, and age-related magnesium out-diffusion. Higher fat content in older bones contributed to increased mass loss. Phosphorus content remained constant across age groups, while calcium and sodium showed age-related fluctuations. Magnesium levels decreased with age, emphasizing its importance for early bone development. The Ca/P ratio deviated from the stoichiometric values due to additional ions from biogenic sources. Infrared spectroscopy identified functional groups in carbonated HAp, with changes observed before and after calcination. The full width at half maximum (FWHM) of the 961 cm-1 band decreased with age, indicating improved crystalline quality. The molar absorption coefficients provided information on the changes in molecular concentration and emphasized the differences between the age groups. X-ray analysis revealed nanocrystalline HAp in all samples, with crystallite size increasing with age. Rietveld analysis showed that the lattice parameters were affected by the presence of organic material, but the lattice constants remained stable, confirming high crystallinity independent of age. TEM analysis confirmed nanocrystalline structures, with crystallite size increasing with age. SEM images showed the characteristic porosity of calcined HAp, with particle size correlating positively with age. Calcination at 600°C preserved the nanoscale properties and microcrystal formation. Raman spectroscopy confirmed the identity of HAp, with FWHM variations indicating age-related changes in crystalline quality. EHAp1 showed increased FWHM, indicating lower crystalline quality and increased trace element content.

Structural Defects on Graphene Generated by Deposition of CoO: Effect of Electronic Coupling of Graphene.

Understanding the interactions in hybrid systems based on graphene and functional oxides is crucial to the applicability of graphene in real devices. Here, we present a study of the structural defects occurring on graphene during the early stages of the growth of CoO, tailored by the electronic coupling between graphene and the substrate in which it is supported: as received pristine graphene on polycrystalline copper (coupled), cleaned in ultra-high vacuum conditions to remove oxygen contamination, and graphene transferred to SiO2/Si substrates (decoupled). The CoO growth was performed at room temperature by thermal evaporation of metallic Co under a molecular oxygen atmosphere, and the early stages of the growth were investigated. On the decoupled G/SiO2/Si samples, with an initial low crystalline quality of graphene, the formation of a CoO wetting layer is observed, identifying the Stranski-Krastanov growth mode. In contrast, on coupled G/Cu samples, the Volmer-Weber growth mechanism is observed. In both sets of samples, the oxidation of graphene is low during the early stages of growth, increasing for the larger coverages. Furthermore, structural defects are developed in the graphene lattice on both substrates during the growth of CoO, which is significantly higher on decoupled G/SiO2/Si samples mainly for higher CoO coverages. When approaching the full coverage on both substrates, the CoO islands coalesce to form a continuous CoO layer with strip-like structures with diameters ranging between 70 and 150 nm.

Physical characterizations of Se-doped CdS nanostructures

The investigation thoroughly analyzes undoped and Se-doped CdS nanostructures using multiple techniques. Elemental composition analysis via EDS showed pure Cd and S in the undoped sample, while successful Se incorporation was confirmed in Se-doped samples. XRD revealed distinct CdS phases, with reduced intensity and broadening after Se-doping, indicating lower crystalline quality. The (111) peak shift confirmed Se substitution in the CdS lattice. Williamson-Hall and Monshi-Scherrer analyses demonstrated smaller crystallite sizes and increased lattice strain after Se-doping. FESEM displayed smaller grain sizes after Se-doping. PL analyses showed diminished crystalline quality and reduced intensity. UV–Vis indicated increased absorption and reduced transmission after Se-doping. Bandgap energy declined due to Se-doping and potential CdSe phase formation. Raman spectroscopy confirmed reduced crystalline quality. Se-doping enhances photon absorption, potentially improving optical properties for diverse applications. The study provides a detailed assessment of Se-doped CdS nanostructures, highlighting structural, optical, and morphological changes, valuable for various technological applications.

Reduction of oxygen vacancies in Mg–N codoped Ga2O3 films for improving solar-blind UV photodetectors performance

Solar-blind photodetectors based on gallium oxide (Ga2O3) have shown possibilities in optical imaging, spatial communication, and other fields. The high oxygen vacancy (VO) content inherent in Ga2O3 film would inevitably result in poor photoelectric detection capability. This work suggests using a codoping for reducing VO concentrations in Ga2O3 films. In a N2O atmosphere, magnesium and nitrogen codoped gallium oxide (Mg–N:Ga2O3) films were grown using the pulsed laser deposition (PLD) technique on (0001) sapphire substrates. It is possible to produce codoped Ga2O3 thin films with low oxygen vacancy density and high crystalline quality by thoroughly examining and optimizing preparation conditions. Metal-semiconductor-metal (MSM) photodetectors were constructed using both pristine and Mg–N codoped Ga2O3 thin films as the active layer. The photodetector with a codoped active layer outperforms those with pristine Ga2O3, with a quick decay time of 20 ms, a high sensitivity of 2.61 × 105, and a high responsivity of 0.191 A/W under 254 nm UV light irradiation, highlighting the significance of the VO concentration decrease in the application of Ga2O3-based solar-blind photodetectors.

Revealing the influence of aerosol particle state on the high-quality α-Ga2O3 single crystal thin film growth by Mist CVD epitaxy

There is little research on α-Ga2O3 single crystal film because it is a metastable phase of Ga2O3 crystal and difficult for controllable fabrication. In this paper, highly crystallized Ga2O3 thin films of poly-crystalline, α-Ga2O3 and β-Ga2O3 were prepared by modulating the growth temperature from 400 °C to 700 °C by mist-assisted CVD (Mist CVD) method. The results show that films grown at 525 °C owes the best crystalline quality of α-Ga2O3 film. To further improve the crystallinity of α-Ga2O3 thin film, a systematic simulation revealing the distribution changes of aerosol particle size, flow field, and temperature gradient in the reaction chamber were explored. The optimal growth region C with uniform particle size, well-distribute temperature gradient and stable flow field is determined. Meanwhile, the experimental results of α-Ga2O3 thin films grown at different positions in the reaction chamber was proved to consistent with the simulation results. Furthermore, the optimal single crystallized α-Ga2O3 thin films with smooth surface morphology and optical property were obtained. The PL spectrum operated at room temperature show the α-Ga2O3 film with low defect density and high crystalline quality. It shows that the single crystallized α-Ga2O3 is orientated grown on sapphire substrate with epitaxial relationship of α-Ga2O3 (0006)//c-Al2O3 (0006). Although, slight lattice mismatch is observed on the selected area electron diffraction pattern of the interface between sapphire and α-Ga2O3 film, it is ideal for further application in devices. This work reveals the key point for α-Ga2O3 single crystal film growth by mist CVD is to construct a steady and orderly environment through controlling aerosol particle state.

Lithium Polyacrylate as Lithium and Carbon Source in the Synthesis of Li3 VO4 for High-Rate and Long-Life Li-Ion Batteries.

Li3 VO4 is a promising anode material for use in lithium-ion batteries, however, the conventional synthesis methods for Li3 VO4 anodes involve the separate use of lithium and carbon sources, resulting in inefficient contact and low crystalline quality. Herein, lithium polyacrylate (LiPAA) was utilized as a dual-functional source and an in-situ polymerization followed by a spray-drying method was employed to synthesize Li3 VO4 . LiPAA serves a dual purpose, acting as both a lithium source to improve the crystal process and a carbon source to confine the particle size within a desired volume during high-temperature treatment. Additionally, the in-situ synthesis of a porous carbon decorating skeleton prevents the growth and agglomeration of Li3 VO4 particles and provides abundant ion/electron diffusion channels and contact areas. Based on the synthesis route and the constructed primary-secondary structure, the Li3 VO4 anodes obtained in this study exhibit an impressive capacity of 596.2 mAh g-1 . Moreover, they demonstrate enhanced rate performance over 600 cycles during 10 periods of rate testing, as well as a remarkably long lifespan of 5000 cycles at high currents. The utilization of LiPAA as a dual-functional source represents a broad approach that holds great potential for future research on high-performance electrodes requiring both lithium and carbon sources.

Selective area growth of high quality GaN nanocolumns on Si(0 0 1) by plasma assisted molecular beam epitaxy

Two different arrays of GaN nanocolumns, with average diameters of 140 nm and 260 nm, were selectively grown by molecular beam epitaxy on GaN-buffered on-axis Si(001) substrates. Footprint of the nanocolumns with respect to the grain size of the GaN buffer layer plays and important role on the crystalline quality of the nanocolumnar material. Despite the rather low crystalline quality of the GaN buffer, very high quality GaN nanocolumns were achieved in the case of the array with 140 nm average diameter, as indicated from a low temperature photoluminescence donor-bound exciton linewidth of 1.9 meV and negligible densities of stacking faults and threading dislocations determined by transmission electron microscopy. These results may help to the integration of GaN-based nano-devices with the conventional Si(001) electronics platform.

High-performance photodetector based on semi-encompassed CH3NH3PbCl3–ZnO microwire heterojunction with alterable spectral response

Recently, heterojunctions consisting of hybrid organic-inorganic lead (Pb) halide perovskites and other semiconductors have drawn increasing attention for the potential application in photodetectors due to their exceptional performance. However, their performance is usually limited by the relatively low crystalline quality of perovskites, and the response spectra of the devices are difficult to adjust according to the practical requirement. Here, high quality CH3NH3PbCl3 micro-sized crystals have been successfully fabricated on one side of individual ZnO microwire to form heterojunction photodetector by a two-step crystallization method. The heterojunction device presents a low dark current (60 nA at −6 V) along with a rapid response speed (rise time of <20 μs and fall time of ∼500 μs). More interestingly, the modulation of the response spectra and the responsivity can be realized by operating the device under front or back illumination due to the self-filtering properties. Our findings provide a promising method for combining perovskites with other inorganic materials to form high-performance heterojunction photodetectors.

Investigation of structural and electrical properties of ITO thin films and correlation to optical parameters extracted using novel method based on PSO algorithm

Thermally annealed DC sputtered indium tin oxide (ITO) thin films were investigated for improvement in properties. The structural and optoelectronic characteristics of as-grown and air annealed films were studied and correlated to the film deposition time. Raman spectroscopy analysis showed low crystalline quality films for as-grown films and were significantly improved after annealing. X-ray diffraction analysis confirmed the crystallinity of samples with (222) preferential orientation. The 30-min ITO films showed a peak at (400). The films optical study shows an increased transmittance (in the transparency region) with decreasing deposition time, yielding a high transparency of 90% for the 5- and 15-min ITO films annealed at 400°C. The films thickness and optical constants were determined from optical transmission only without interference fringe using a novel method based on particle swarm optimization (PSO) algorithm. The absorption coefficient and calculated refractive index decreased with increasing deposition time and their value reduced further after annealing treatment. The 30-min ITO films showed a comparable low resistivity of 4 × 10−3 Ω cm before and after annealing as determined by Hall effect measurements. This observation confirms their non-sensitivity to the oxygen post-contamination that resulted from (400) orientation. A shift of the absorption edge towards shorter wavelengths accompanied with an increase in the optical bandgap before and after annealing with decreasing thickness were observed. We have demonstrated that the optical parameters such as the optical gap depend mainly on the electrical parameters such as the carrier concentration.

Suppression of (0001) plane emission in GaInN/GaN multi-quantum nanowires for efficient micro-LEDs.

GaInN/GaN multi-quantum-shell (MQS) nanowires (NWs) are gaining increasing attention as promising materials for developing highly efficient long-wavelength micro-light emitting diodes (LEDs). To improve the emission properties in GaInN/GaN MQS NWs, it is necessary to suppress the emission from the (0001) c-plane MQS at the apex region, which featured with low crystalline quality. In this study, we investigated the enhancement of optical properties and the realization of micro-LEDs by confirming the effect of the (0001) plane region. A 7.9-fold enhancement of the electroluminescence (EL) intensity was demonstrated by removal the (0001) plane region via inductively coupled plasma (ICP) dry etching, owing to the promoted current injection into the (1-101) semi-polar and (10-10) non-polar sidewall area. To investigate the effect of the emission area on the samples with and without truncated (0001) plane region, devices with three different mesa areas (50 × 50, 100 × 100, and 100 × 200μm2) were fabricated. An increased EL intensity with the reduced mesa areas was observed in the samples without dry etching of the (0001)-plane area, because more current can be injected into the sidewall region with higher crystalline quality and luminous efficiency than the (0001)-plane MQS. Under the same injection current density, the truncated samples' light output was increased for more than ten times as compared to the samples without (0001)-plane etching. Therefore, it confirms the possibility of realizing highly efficient GaInN/GaN MQS NWs LEDs by eliminating the (0001) plane MQS region. A precise etching and surface passivation of the apex region is expected to further reduce the reverse leakage current and improve the performance in NW-LEDs.

Highly aligned organic microwire crystal arrays for high-performance polarization-sensitive photodetectors and image sensors

Organic semiconductors with excellent optoelectronic properties are important building blocks for high-performance organic devices. Patterning organic crystals with high precision and accurately positioning them at the target position are major challenges for integrated devices. However, uncontrollable dewetting of the conventional solution method leads to as-prepared micro-nanocrystals with high defect-state density, low crystalline quality, and disordered distribution, which impair the uniformity of the device performance and limit integration. By regulating the solution position with a template and guiding the solution flow direction under gravity, aligned organic microwire arrays and polygonal patterns were fabricated. The polarization-sensitive photodetector exhibited responsivity up to 1234 A W−1, linear dynamic range of 148 dB, Iphoto/Idark of 104, response time as low as 1.1 ms, and dichroic ratio up to 2.1. Given the homogeneity of microwire arrays, the device-to-device variation was reduced to 3.58%, resulting in high-quality imaging. This study provides new insights into organic micro/nanocrystal patterning and device integration.

Boron Phosphide Films by Reactive Sputtering: Searching for a P‐Type Transparent Conductor

AbstractWith an indirect band gap in the visible and a direct band gap at a much higher energy, boron phosphide (BP) holds promise as an unconventional p‐type transparent conductor. This work reports on reactive sputtering of amorphous BP films, their partial crystallization in a P‐containing annealing atmosphere, and extrinsic doping by C and Si. The highest hole concentration to date for p‐type BP (5 × 1020cm−3) is achieved using C doping under B‐rich conditions. Furthermore, bipolar doping is confirmed to be feasible in BP. An anneal temperature of at least 1000 °C is necessary for crystallization and dopant activation. Hole mobilities are low and indirect optical transitions are stronger than that predicted by theory. Low crystalline quality probably plays a role in both cases. High figures of merit for transparent conductors might be achievable in extrinsically doped BP films with improved crystalline quality.

Correlation of Morphology Evolution with Carrier Dynamics in InN Films Heteroepitaxially Grown by MOMBE

In this study, we report the catalyst-free growth of n-type wurtzite InN, along with its optical properties and carrier dynamics of different surface dimensionalities. The self-catalyzed epitaxial growth of InN nanorods grown by metal–organic molecular-beam epitaxy on GaN/Al2O3(0001) substrates has been demonstrated. The substrate temperature is dominant in controlling the growth of nanorods. A dramatic morphological change from 2D-like to 1D nanorods occurs with decreasing growth temperature. The InN nanorods have a low dislocation density and good crystalline quality, compared with InN films. In terms of optical properties, the nanorod structure exhibits strong recombination of Mahan excitons in luminescence, and an obvious spatial correlation effect in phonon dispersion. The downward band structure at the nanorod surface leads to the photon energy-dependent lifetime being upshifted to the high-energy side.

Influence of Precursor Concentration on Crystalline Quality of GaN Thin Films Grown on a Sapphire Wafer

Abstract Chemical vapor deposition (CVD), which involves chemical reactions in gases for deposition on a heated surface, is an extensively used manufacturing technique for obtaining thin films of materials like silicon, graphene, silicon carbide, aluminum nitride, and gallium nitride (GaN). The process is driven by heat and mass transfer, fluid flow, and chemical reactions in the gases and at the surface. GaN is one of the most promising materials for manufacturing optical and electronic devices. However, the reliability and durability of the GaN-based devices depend on the crystalline quality of the thin films used. In this study, the epitaxial growth of GaN thin films on sapphire (Al2O3) wafers is carried out in a vertical rotating disk metalorganic chemical vapor deposition (MOCVD) system. Epitaxial growth refers to the process of growing a crystal of a particular orientation on the top of another crystal, with the orientation being determined by the underlying crystal. MOCVD reactors are CVD systems that use metalorganic compounds that consist of metal and organic ligands, leading to materials like GaAs, AlN, InN, and GaN. The quality of the thin films is largely determined by the choice of operating conditions such as the flowrate, surface temperature, and concentration of the metalorganic precursors that decompose due to heat in the reactor, react, and deposit the desired material on the surface of a wafer or a heated susceptor. In this experimental study, the crystalline quality and surface morphology of GaN thin films are evaluated using atomic force microscopy (AFM), X-ray diffraction (XRD), and Raman spectroscopy. The correlation between the crystalline quality of GaN thin films and the flowrate of the precursors is examined in detail on the basis of an evaluation of the dislocation density. The results indicate that a low concentration (V/III) ratio, where V and III refer to elements in the fifth and third groups of the periodic table, is beneficial for obtaining a high deposition rate since a low value of this ratio implies a high precursor concentration. However, it negatively affects the crystalline quality of the thin film. Similarly, high V/III ratios lead to low deposition rates and better crystalline quality, indicating the need to optimize the process.

Solution-Processed Epitaxial Growth of MAPbI3 Single-Crystal Films for Highly Stable Photodetectors

Recent years, organic-inorganic hybrid perovskites (OIHPs) have been widely used in applications, such as solar cells, lasers, light-emission diodes, and photodetectors due to their outstanding optoelectronic properties. Nowadays photodetectors based on perovskite films (PFs) suffer from surface and interface traps, which result from low crystalline quality of perovskite films and lattice mismatch between perovskite films and substrates. Herein, we fabricate MAPbI3-(MA = CH3NH3) single-crystal films (SCFs) on MAPbBr3single crystal substrates in MAPbI3precursor solution during crystallization process via solution-processed epitaxy. Benefit from the good lattice matching, epitaxial MAPbI3SCFs with high crystallinity and smooth morphology are of comparable quality to MAPbI3PSCs and are of better quality than MAPbI3polycrystalline films. Here we report that epitaxial MAPbI3SCFs have a low trap density of 5.64×1011cm–3and a long carrier lifetime of 11.86 μs. In this work, photodetector based on epitaxial MAPbI3single-crystal film (SCF) exhibits an excellent stability of a long-term stable response after 120 days, a fast response time of 2.21 μs, a high responsivity of 1.2 A W–1and a high detectivity of 3.07 ×1012jones.

Tunnel Junctions with a Doped ( In,Ga)N Quantum Well for Vertical Integration of III -Nitride Optoelectronic Devices

Properties of tunnel junctions (TJs) grown by plasma-assisted molecular beam epitaxy are investigated. Examined TJs consist of a ($\mathrm{In},\mathrm{Ga})\mathrm{N}$ quantum well (QW) sandwiched between ${\mathrm{In}}_{0.02}{\mathrm{Ga}}_{0.98}\mathrm{N}$ barriers. The influence of piezoelectric polarization, doping, and width of a TJ QW on resistivity of TJs is studied. A decrease of TJ resistivity is observed for high doping and high ($\mathrm{In},\mathrm{Ga})\mathrm{N}$ composition. Additionally, the crystal quality of TJs as a function of magnesium and silicon doping in a ($\mathrm{In},\mathrm{Ga})\mathrm{N}$ QW is discussed. Generation of defects in highly doped layers is observed in transmission electron microscopy and by defect selective etching. High doping leads to deterioration of surface morphology, which is corroborated by atomic force microscopy imaging. TJs with low resistance and high crystalline quality, without formation of structural defects, are demonstrated. A theoretical model for calculation of tunneling currents is proposed based on Kane tunneling theory, which considers a realistic electric field distribution in a TJ. A good agreement with the experimental data is obtained. The model is used to predict electrical parameters in a wide range of ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$ compositions (x = 0--0.40), doping (${n}_{\mathrm{Mg},\mathrm{Si}}={10}^{17}\ensuremath{-}5\ifmmode\times\else\texttimes\fi{}{10}^{21}\phantom{\rule{0.25em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$), and TJ QW width (d = 2 -- 12 nm).

The Influence of AlN Nucleation Layer on Radio Frequency Transmission Loss of AlN‐on‐Si Heterostructure

Reducing radio frequency (RF) transmission loss is a key requirement when fabricating GaN‐on‐Si RF devices. To get a better insight into the RF loss mechanism in the GaN‐on‐Si structure, the RF loss of an AlN/Si template is investigated by varying the growth temperature of AlN during a metalorganic chemical vapor deposition process. The results show that the RF loss of the AlN/Si template is dominated by the interface loss due to the p‐type conductive channel at the AlN/Si interface, which is induced by the thermal diffusion of Al during the high‐temperature growth. Although a low growth temperature of the AlN nucleation layer can suppress the RF loss in the AlN/Si template, it results in a low crystalline quality of AlN for practical use. Optimizing the growth temperature of the AlN nucleation layer is essential to obtain a good balance between the crystalline quality, morphological quality, and RF loss such that the AlN/Si template is suitable for epitaxial growth of the complete GaN‐on‐Si RF device structure.

Quasi One-Dimensional Metal-Semiconductor Heterostructures.

The band offsets occurring at the abrupt heterointerfaces of suitable material combinations offer a powerful design tool for high performance or even new kinds of devices. Because of a large variety of applications for metal-semiconductor heterostructures and the promise of low-dimensional systems to present exceptional device characteristics, nanowire heterostructures gained particular interest over the past decade. However, compared to those achieved by mature two-dimensional processing techniques, quasi one-dimensional (1D) heterostructures often suffer from low interface and crystalline quality. For the GaAs-Au system, we demonstrate exemplarily a new approach to generate epitaxial and single crystalline metal-semiconductor nanowire heterostructures with atomically sharp interfaces using standard semiconductor processing techniques. Spatially resolved Raman measurements exclude any significant strain at the lattice mismatched metal-semiconductor heterojunction. On the basis of experimental results and simulation work, a novel self-assembled mechanism is demonstrated which yields one-step reconfiguration of a semiconductor-metal core-shell nanowire to a quasi 1D axially stacked heterostructure via flash lamp annealing. Transmission electron microscopy imaging and electrical characterization confirm the high interface quality resulting in the lowest Schottky barrier for the GaAs-Au system reported to date. Without limiting the generality, this novel approach will open up new opportunities in the syntheses of other metal-semiconductor nanowire heterostructures and thus facilitate the research of high-quality interfaces in metal-semiconductor nanocontacts.

Effect of the crystal size on the infrared and Raman spectra of bio hydroxyapatite of human, bovine, and porcine bones

AbstractThe optical properties of hydroxyapatites (HAps) and bio HAps have been studied using Raman and infrared (IR) spectroscopies to describe their crystalline quality. However, the size of the HAp crystals and their crystalline order effects have not been considered yet. This paper focuses on the study of the effect of the change in the crystallites size have on the width of the IR and Raman spectra for defatted and deproteinized bones as well as incinerated biogenic HAp obtained from bovine, porcine, and human bones. Bone samples were analyzed through Raman and IR spectroscopies, X‐ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma (ICP), and scanning electron microscopy (SEM). The Raman and IR spectra for raw samples showed broad bands but, after calcination at 720 °C, became narrow and well defined. TEM images showed that all raw crystallites are ordered nanoplates contrary to the so far well‐established concept that biogenic HAps have low crystalline quality. XRD data confirmed that raw samples display broad peaks that correlated with the HRTEM images of ordered nanocrystals. This fact confirmed that the broad Raman and IR bands of raw clean bones come from nanocrystal plates. SEM analysis confirmed the increase in the crystal size after calcination from nanomicron to submicron dimensions due to a coalescence phenomenon. These results imply that the interpretation of Raman and IR spectra in the case of HAp nanoparticles has been erroneous. These results contribute to the design of biomaterials for tissue engineering based on biogenic HAp for bone regeneration.