Cross-sectional Transmission Electron Microscopy Research Articles

Hexagonal Boron Nitride Seed Layer-Assisted van der Waals Growth of BaSnO3 Perovskite Films.

We have succeeded in obtaining BaSnO3 perovskite thin films with remarkable near-infrared luminescence by van der Waals growth. The films were grown on quartz glass substrates by pulsed laser deposition using hexagonal boron nitride as the seed layer, and their crystallinity was confirmed by X-ray diffraction and cross-sectional transmission electron microscopy. The near-infrared emission of the grown film exhibited a broad emission peak centered at 920 nm. The transparency of the BaSnO3 film (thickness = 1000 nm)/ hexagonal boron nitride /double-sided optically polished quartz glass substrate was approximately 90% at approximately 500 nm with or without the BaSnO3 film. Films showing remarkable near-infrared emission and high transparency obtained by van der Waals-type growth could be used in practical wavelength conversion devices that improve the efficiency of Si single-crystal solar cells. The hexagonal boron nitride seed layer supporting the van der Waals growth is an effective method for high-quality crystal growth of films. It can be used for perovskite-type oxides with many functionalities.

Structure and electrical conductivity of Ti-Zr-Ni films of quasicrystalline and related crystalline phases

The temperature dependence of electrical resistivity in the temperature range from 4.4 to 300 K for Ti41Zr41Ni18 (at.%) thin coatings of various crystal perfection and phase compositions has been investigated. The films were deposited by the magnetron sputtering method. The following vacuum annealing in various modes provided several combinations of the film phases such as 1/1 and 2/1 crystal-approximant phases, the quasicrystalline icosahedral phase, Laves (Ti,Zr)2Ni phase and α-Ti(Zr) solid solution phase. The structure and composition of the films before and after annealing were studied in detail by X-ray diffractometry and cross-sectional high-resolution transmission electron microscopy. Samples with predominant amorphous, quasi-crystalline, and approximant 2/1 phases have a temperature coefficient of resistance less than zero, while samples dominated by crystalline phases exhibit the characteristic metallic conductivity. For the quasicrystalline Ti41Zr41Ni18 film, the temperature dependence of the electrical resistance turned out to be similar to that of bulk samples with the composition Ti40Zr40Ni20. A significant effect of the presence of phases with metallic conduction on the overall conductivity of the coating is described. The electrical resistance of the 2/1 approximant phase with a low content of the additional Laves phase in the film has an almost constant value over the entire temperature range under study.

Thick p-type Mg2Si film on Si: Growth, structure and transport properties

A ∼ 0.8–0.9 µm thick Mg2Si film was grown by pulsed deposition of Mg on Si(111) at 340 °C in UHV. The X-Ray Diffraction (XRD) and cross-sectional High-resolution Transmission Electron Microscopy (x-HRTEM) data demonstrate the high crystal quality and nearly 100% texture of the film. Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) depth profiling show that the synthesized Mg2Si contains some oxygen. Hall measurements reveal the p-type conductivity of 130 S/cm and carrier concentration of 6 × 1018 cm−3 at room temperature (RT), the acceptor concentration of ∼ 1.4 × 1018 cm−3 at 190 K, hole activation energy Ea ≈ 26 meV, mobility μ∼5050 cm2/V∙s at 75 K and μ∼134 cm2/V∙s at RT. The p-type conductivity is related to either unintentional doping with oxygen or/and Mg vacancies occurred during the non-equilibrium process of silicide ultra-fast formation. The outstanding transport parameters of the film are explained by its high crystal quality and texture. The films with such thickness and transport properties are suitable for photovoltaic and thermoelectric applications.

Ultrathin Pt and Mo films on Al1–xScxN: an interface investigation

Aluminum scandium nitride (Al1–xScxN) with attractive ferroelectric and piezoelectric properties is a promising material for next-generation device applications. However, the understanding of interface properties between integrated ultrathin metal electrodes and Al1-xScxN films is still limited, despite their significant impact on device performance. In the study, we investigated the growth mechanism and interfacial chemistry of ultrathin platinum (Pt) and molybdenum (Mo) films deposited on the high-crystalline Al1-xScxN (x = 0.2) surface. The chemical and electronic structure evolutions of the interface during the deposition process were probed by in-situ X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The structural properties of the interface were further characterized by cross-sectional transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), and atomic force microscopy (AFM). Our results reveal the formation of ionic Pt2+-N bonds at the Pt/Al1-xScxN interface, while Mo does not bond with the substrate. Furthermore, we identified electron transfer induces upward band-bending like effects on the Al1-xScxN surface upon both Pt and Mo interactions. Our work on the chemical and structural research of ultrathin metal electrodes and Al1–xScxN interfaces provides guidance towards designing high-performance micro-electromechanical (MEMS) devices.

Observation of comet-shaped defect as killer defect in halide vapor phase epitaxial (001) β-Ga2O3 and its impact on Schottky barrier diodes

We observed killer defects that served as reverse leakage current paths for halide vapor phase epitaxial (001) β-Ga2O3 Schottky barrier diodes, which resulted in a leakage current of −0.46 μA at reverse bias of −100 V. Synchrotron X-ray topography revealed comet-shaped contrasts extending along [010] which are induced from the strain field surrounding the defects. They consisted of perfect (100)-cracks and horizontal-oriented (001) cracks. The cross-sectional scanning transmission electron microscopy observation showed (100)-cracks on the surface and dislocations along [100] beneath the surface. This defect was speculated to be generated from damage during the chemical-mechanical polishing.

Decomposition pathways in nano-lamellar CVD Ti0.2Al0.8N

Recent progress in chemical vapour deposition (CVD) technology has enabled synthesis of metastable cubic Ti1−xAlxN coatings with x as high as 0.8–0.9. These coatings have unique micro- and nano-structures consisting of grains with epitaxially grown nanolamellae with different Al/Ti ratios, and exhibit exceptional hardness and resistance to wear and oxidation. Here, the thermal stability and decomposition of nano-lamellar CVD Ti0.2Al0.8N at temperatures between 800 and 1000 °C have been investigated using a combination of cross-sectional transmission X-ray nano-diffraction and scanning transmission electron microscopy. The decomposition started by formation of hexagonal AlN (h-AlN) in the grain boundaries throughout the coating. Below 900 °C, only limited further decomposition of the grain interiors occurred. At higher temperatures the formation of grain boundary h-AlN was followed by a bulk transformation of the nano-lamellar structure, starting at the top of the coating and subsequently sweeping inwards. The bulk transformation occurred initially through spinodal decomposition, followed by transformation of the Al-rich cubic phase to h-AlN, leading to a coarsened structure with Ti-rich domains in a h-AlN matrix. The behaviour is explained by the higher capability of grain boundaries and free surfaces to accommodate the volumetric expansion from the h-AlN formation. The results increase our understanding of the complicated decomposition processes in these metastable cubic coatings, which are of utmost importance from both technological and scientific perspectives.

Laser induced diamond/graphite structure for all-carbon deep-ultraviolet photodetector

Graphite was formed by in-situ structural conversion from sp3 to sp2 hybridized carbon via KrF excimer. The surface morphology of diamond was changed to nanoparticles after laser irradiation. Raman peak related to amorphous carbon emerged after laser treatments with energy of 10 ∼ 25 mJ cm−2. X-ray photoelectron spectroscopy exhibited that surface graphitization could take place under low laser energy of 2 mJ cm−2. The structural transformation of diamond after laser irradiation was further studied by cross-sectional transmission electron microscopy (TEM) analysis. The TEM results displayed that the diamond/graphite interface was gradually transformed from diamond to graphite, and the transformation process was verified by molecular dynamics simulations. The specific contact resistance of 7.83 × 10-5 Ω cm2 for the diamond/graphite structure was acquired by transmission line model. Meanwhile, the barrier height of the graphite/diamond contact was obtained to be 0.54 eV. In the end, an all-carbon deep-ultraviolet photodetector with diamond/graphite structure was developed. The all-carbon photodetector exhibited relatively high responsivity of 15 mA/W under 220 nm illumination, and a fast transient response of 86 μs.

Molecular beam epitaxy and crystal structure of majority a-plane-oriented and substrate-strained Mn3Sn thin films grown directly on sapphire (0001)

The Kagome antiferromagnet Mn3Sn has garnered much attention due to the presence of exciting properties such as anomalous Hall and Nernst effects. This paper discusses the synthesis of crystalline Mn3Sn thin films, prepared on Al2O3 (0001) substrates at 453±5°C using molecular beam epitaxy. The growth is monitored in situ using reflection high energy electron diffraction and measured ex situ using x-ray diffraction, Rutherford back-scattering, and cross-sectional scanning transmission electron microscopy. Our analysis shows the in-plane lattice constants of a1,M=4.117±0.027 Å and a2,M=4.943±0.033 Å, which is a very unexpected result when compared to the bulk a-plane Mn3Sn. This indicates a strain in the film and makes it challenging to provide a straightforward explanation. In an effort to explain our results, we discuss two possible orientation relationships between the Mn3Sn films and the sapphire substrates. Samples prepared under these conditions appear to have smooth surfaces locally, but overall the film has a 3D island morphology. First-principles calculations provide atomic models of the Mn3Sn (112¯0) lattice on Al2O3 (0001) high symmetry sites, indicating that the L3-R90° is the most stable configuration. A detailed discussion of the experimental data and theoretical results, as well as strain effects, is provided.

Thickness-dependent carrier transport of PdSe2 films grown by plasma-assisted metal selenization

Atomically thin narrow-bandgap layered PdSe2 has attracted much attention due to its rich and unique electrical properties. For silicon-compatible device integration, direct wafer-scale preparation of high-quality PdSe2 thin film on a silicon substrate is highly desired. Here, we present the low-temperature synthesis of large-area polycrystalline PdSe2 films grown on SiO2/Si substrates by plasma-assisted metal selenization and investigate their charge carrier transport behaviors. Raman analysis, depth-dependent x-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy were used to reveal the selenization process. The results indicate a structural evolution from initial Pd to intermediate PdSe2–x phase and eventually to PdSe2. The field-effect transistors fabricated from these ultrathin PdSe2 films exhibit strong thickness-dependent transport behaviors. For thinner films (4.5 nm), a record high on/off ratio of 104 was obtained. While for thick ones (11 nm), the maximum hole mobility is about 0.93 cm2 V−1 S−1, which is the record high value ever reported for polycrystalline films. These findings suggest that our low-temperature-metal-selenized PdSe2 films have high quality and show great potential for applications in electrical devices.

Self-Aligned Nanopatterning and Controlled Lateral Growth by Dual-Material Orthogonal Area-Selective Deposition of Poly(3,4-ethylenedioxythiophene) and Tungsten

Despite recent advances in area-selective deposition (ASD) processes, most studies have focused on single-material ASD. Multi-material ASD processes could provide additional flexibility for fabricating semiconductor devices. In this work, we identify process requirements to sequentially combine two intrinsic ASD processes: (1) poly(3,4-ethylenedioxythiophene) (PEDOT) ASD on SiO2 vs Si–H via oxidative chemical vapor deposition and (2) W ASD on Si–H vs SiO2 via atomic layer deposition. Using ex situ X-ray photoelectron spectroscopy, we show that a preferred orthogonal ASD sequence involves PEDOT ASD on SiO2 vs Si–H, followed by W ASD on Si–H vs PEDOT. We find that the properties of the individual PEDOT and W ASD materials, including resistivity, surface roughness, and growth rate, are affected by the ASD sequence. Furthermore, we successfully demonstrate that orthogonal ASD can be extended to nanoscale starting patterns. The cross-sectional scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy analysis shows that the resulting PEDOT thickness on SiO2 depends on feature geometry and dimension. Finally, we demonstrate the feasibility that the PEDOT layer can control the lateral growth of W onto the non-growth surface.

Whereabouts of missing atoms in a laser-injected Si (Part III)

ABSTRACT Microstructure of laser induced modified volume (LIMV) in Si was examined using transmission electron microscopy (TEM) and infra-red optical microscopy. Dominant features of LIMV are voids, dislocations, cracks and non-DS phases of Si. Nucleation of dislocations and cracks can be accounted for by dilatation caused by local temperature rise near the focus of laser. Mass of Si wafer before and after laser injection was conserved by laser injection. Therefore, those Si atoms which must have existed in pre-void, that is, that area which on laser injection is transformed to void, also stay in Si matrix. The void is thermally stable up to ∼800oC, however, it becomes unstable above ∼800oC. That is, void (or LIMV) fades above ∼800oC under infra-red optical microscope. In TEM, after annealing at 1000oC, 1∼a few μm diameter voids which had been present in the as-laser-injected Si, disappeared and very fine voids (nano-voids) appeared. In the cross-sectional TEM of LIMV sitting near the exiting surface of laser beam, a gap was observed between the exiting surface and a protective coat (W). Si atoms in pre-void become plasmas on laser irradiation. In other words, Si atom is dissociated into Si+n and n free electrons (n =1 ∼ 14). The ionized Si (Si+n) forms a void but some of them are dispersed in the adjacent matrix of DS-Si. On the other hand, free electrons gain a high energy and travel far away from the void: The ionized Si (Si+n) and free electrons do not recombine to annihilate.

Dynamic Electrode–Electrolyte Intermixing in Solid-State Sodium Nano-Batteries

Nanostructured solid-state batteries (SSBs) are poised to meet the demands of next-generation energy storage technologies by realizing performance competitive to their liquid-based counterparts while simultaneously offering improved safety and expanded form factors. Atomic layer deposition (ALD) is among the tools essential to fabricate nanostructured devices with challenging aspect ratios. Here, we report the fabrication and electrochemical testing of the first nanoscale sodium all-solid-state battery (SSB) using ALD to deposit both the V2O5 cathode and NaPON solid electrolyte followed by evaporation of a thin-film Na metal anode. NaPON exhibits remarkable stability against evaporated Na metal, showing no electrolyte breakdown or significant interphase formation in the voltage range of 0.05-6.0 V vs Na/Na+. Electrochemical analysis of the SSB suggests intermixing of the NaPON/V2O5 layers during fabrication, which we investigate in three ways: in situ spectroscopic ellipsometry, time-resolved X-ray photoelectron spectroscopy (XPS) depth profiling, and cross-sectional cryo-scanning transmission electron microscopy (cryo-STEM) coupled with electron energy loss spectroscopy (EELS). We characterize the interfacial reaction during the ALD NaPON deposition on V2O5 to be twofold: (1) reduction of V2O5 to VO2 and (2) Na+ insertion into VO2 to form NaxVO2. Despite the intermixing of NaPON-V2O5, we demonstrate that NaPON-coated V2O5 electrodes display enhanced electrochemical cycling stability in liquid-electrolyte coin cells through the formation of a stable electrolyte interphase. In all-SSBs, the Na metal evaporation process is found to intensify the intermixing reaction, resulting in the irreversible formation of mixed interphases between discrete battery layers. Despite this graded composition, the SSB can operate for over 100 charge-discharge cycles at room temperature and represents the first demonstration of a functional thin-film solid-state sodium-ion battery.

Passivation capping of InAs surface quantum dots by TMA/Al2O3: PL enhancement and blueshift suppression

Passivation capping that enhances the photoluminescence (PL) of molecular beam epitaxy (MBE)-grown InAs surface quantum dots (SQDs) is realized by ex situ low-temperature atomic layer deposition (ALD)-grown Al2O3. As the Al2O3 cap thickness increased from 2 to 30 nm, the PL intensity was enhanced by 2.7-fold and the blue shift was suppressed. This is in strong contrast to wet chemistry passivation and in situ GaAs capping by MBE, both of which resulted in significant PL blueshift, due to etching in the former, and In/Ga intermixing and strain in the latter. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) reveal that the Al2O3 cap layer mimics the shape of the underlying SQDs. The cross-sectional transmission electron microscopy (TEM) further reveals that the SQD size and shape remained unchanged after Al2O3 capping, which is in strong contrast to MBE-capping. The passivation mechanisms and native oxide reduction by trimethylaluminum (TMA), including self-clean-up reaction through ligand exchange, are discussed based on the results by x-ray photoelectron spectroscopy (XPS). A detailed comparison between Al2O3 and ZnO cap layers reveals the significance of the cap properties on the SQD size/shape and PL blueshift. While the size/shape of SQDs is preserved by Al2O3 capping, the apex is slightly removed by ZnO capping, resulting in a stronger PL blueshift compared to Al2O3.

Ohmic contact structures on β-Ga2O3 with n+ β-Ga2O3 pulsed laser deposition layers

Thin (40–150 nm), highly doped n+ (1019–1020 cm−3) Ga2O3 layers deposited using pulsed laser deposition (PLD) were incorporated into Ti/Au ohmic contacts on (001) and (010) β-Ga2O3 substrates with carrier concentrations between 2.5 and 5.1 × 1018 cm−3. Specific contact resistivity values were calculated for contact structures both without and with a PLD layer having different thicknesses up to 150 nm. With the exception of a 40 nm PLD layer on the (001) substrate, the specific contact resistivity values decreased with increasing PLD layer thickness: up to 8× on (001) Ga2O3 and up to 16× on (010) Ga2O3 compared with samples without a PLD layer. The lowest average specific contact resistivities were achieved with 150 nm PLD layers: 3.48 × 10−5 Ω cm2 on (001) Ga2O3 and 4.79 × 10−5 Ω cm2 on (010) Ga2O3. Cross-sectional transmission electron microscopy images revealed differences in the microstructure and morphology of the PLD layers on the different substrate orientations. This study describes a low-temperature process that could be used to reduce the contact resistance in Ga2O3 devices.

Single crystal-single crystal bonding of langasite exhibited high strength of 23.28 MPa

Langasite (LGS, La3Ga5SiO14) is a promising material in high-temperature piezoelectric devices due to its excellent thermal stability, piezoelectricity, and electrical property. A major challenge in the development of LGS-based devices is to form high-strength bonding of the brittle LGS. Here, we report that the single crystal-single crystal (dual-SC) bonding of LGS is realized through thermal activation under a low compression of 50 kPa for the first time. A record bonding strength of 23.28 MPa is achieved within the dual-SC bonded LGS/LGS structure (with a high bonding ratio exceeding 93%), which is 5 times higher than that of the recent reported LGS/LGS bonding structure (in which a relatively fragile amorphous interface layer is formed between the two LGS samples). The smooth and void-free dual-SC bonding interface of LGS is verified via the cross-sectional transmission electron microscopy (TEM) observations.

Fabrication of sub-5 nm uniform zirconium oxide films on corrugated copper substrates by a scalable polymer brush assisted deposition method

We demonstrate a polymer brush assisted approach for the fabrication of continuous zirconium oxide (ZrO2) films over large areas with high uniformity (pin-hole free) on copper (Cu) substrates. This approach involves the use of a thiol-terminated polymethyl methacrylate brush (PMMA-SH) as the template layer for the selective infiltration of zirconium oxynitrate (ZrN2O7). The preparation of a highly uniform covalently grafted polymer monolayer on the Cu substrate is the critical factor in fabricating a metal oxide film of uniform thickness across the surface. Infiltration is reliant on the chemical interactions between the polymer functional group and the metal precursor. A following reductive H2 plasma treatment process results in ZrO2 film formation whilst the surface Cu2O passive oxide layer was reduced to a Cu/Cu2O interface. Fundamental analysis of the infiltration process and the resulting ZrO2 film was determined by XPS, and GA-FTIR. Results derived from these techniques confirm the inclusion of the ZrN2O7 into the polymer films. Cross-sectional transmission electron microscopy and energy dispersive X-ray mapping analysis corroborate the formation of ZrO2 layer at Cu substrate. We believe that this quick and facile methodology to prepare ZrO2 films is potentially scalable to other high-κ dielectric materials of high interest in microelectronic applications.

Effects of GaN channel downscaling in AlGaN–GaN high electron mobility transistor structures grown on AlN bulk substrate

In this work, two series of AlGaN/GaN/AlN high electron mobility transistor (HEMT) heterostructures have been grown by molecular beam epitaxy on AlN bulk substrates. The effects of reduction in the GaN channel thickness as well as the AlGaN barrier thickness and composition on structural and electrical properties of the heterostructures have been studied. The material analysis involved high-resolution x-ray diffraction, atomic force microscopy, and cross-sectional transmission electron microscopy. In a first series of HEMT structures grown with an aluminum content of 30% in the AlGaN barrier, the channel downscaling results in a reduction in the GaN strain relaxation rate but at the expense of degradation in the mean crystal quality and in the electron mobility with a noticeable increase in the sheet resistance. An opposite trend is noticed for the three-terminal breakdown voltage of transistors, so that a trade-off is obtained for a 50 nm width GaN channel HEMT, which exhibits a sheet resistance of 1700 Ω/sq. with transistors demonstrating three-terminal breakdown voltage up to 1400 V for 40 μm gate to drain spacing with static on resistance Ron = 32 mΩ cm2. On the other hand, a second series of HEMT structures with high aluminum content AlGaN barriers and sub-10 nm GaN channels have been grown perfectly strained with high sheet carrier densities allowing to preserve sheet resistances in the range of 880–1050 Ω/sq.

Opto-electronic properties of Zr[formula omitted]Hf[formula omitted]O[formula omitted]/Al/Zr[formula omitted]Hf[formula omitted]O[formula omitted] thin-films: The influence of substrate temperature

The influence of substrate temperature on ZrxHf1−xO2/Al/ZrxHf1−xO2 trilayer thin-films deposited on n-type Si(100) and commercial glass substrates using magnetron sputtering technique is systematically investigated with the substrate temperature ranging from 25 to 300°C. The deposited films are characterized by x-ray reflectivity (XRR), grazing incidence x-ray diffraction (GI-XRD), x-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM), cross-sectional transmission electron microscope (TEM), energy-dispersive x-ray spectroscopy (EDX) and UV–VIS spectroscopy to study the microstructural, morphological and optical properties. Capacitance–voltage (C–V) and current–voltage (I–V) measurements are performed to investigate the electrical properties of the trilayer thin-films. Physical characterization reveals that as the substrate temperature rises, the crystalline quality of the trilayer thin-films improves. Further, a rise in substrate temperature causes an increase in surface roughness and grain size. The trilayer thin-film deposited at 300°C shows improved optical transmittance over wavelengths 400–1100 nm. In addition this trilayer thin-film demonstrates highest figure of merit, lower leakage current as well as improved breakdown performance. Hence, ZrxHf1−xO2/Al/ZrxHf1−xO2 thin-film prepared at 300°C could be used in opto-electronic devices.

Study on the Structure of GaN films deposited on MoS2/Sapphire via Plasma-Assisted Molecular Beam Epitaxy

The gallium nitride (GaN) films were grown on molybdenum disulfide (MoS2) layers via plasma-assisted molecular beam epitaxy (PA-MBE). The heterostructures of the GaN film were studied using reflection high-energy electron diffraction (RHEED) and HR-XRD. The heterostructures of GaN/MoS2/sapphire were revealed through cross-sectional transmission electron microscopy (TEM). The surface texture of the GaN films was analyzed using FE-SEM. Single-crystal heterostructure GaN films can be obtained on 2D MoS2/c-sapphire. The RHEED demonstrated spot patterns with high intensity showing the single crystal structure constructed in the GaN films. The GaN films on the surface exhibited a hexagonal structure. TEM images taken perpendicular to the surface revealed that, even after 60 minutes of epitaxial growth, the thickness of the GaN films remained consistent at approximately 4 nm. However, the 2D MoS2 layer was not observable in the images due to harm incurred during heteroepitaxial growth. Based on the surface structure, it was found that GaN films were successfully grown on the MoS2 layers using the PA-MBE system.

Wide-gamut structural colours on oakblue butterflies by naturally tuned photonic nanoarchitectures.

The iridescent structural colours of butterflies, generated by photonic nanoarchitectures, often function as species-specific sexual signals; therefore, they are reproduced precisely from generation to generation. The wing scales of oakblue hairstreak butterflies (genus Arhopala, Theclinae, Lycaenidae, Lepidoptera) contain multi-layer photonic nanoarchitectures, which can generate a wide range of structural colours, from violet to green. By scanning (SEM) and cross-sectional transmission electron microscopy (TEM) investigation, the colour tuning mechanism of the cover scales was explored. We revealed that the characteristic size change of structural elements in similar photonic nanoarchitectures led to different structural colours that were examined by various reflectance spectrophotometry techniques. The measured structural properties of the naturally tuned photonic nanoarchitectures were used to calculate wing reflectances, which were compared with the measurement results. We found that the simulated structural colours were systematically redshifted by 95-126 nm as compared with the measured normal-incidence reflectance results. This is attributed to the swelling of the chitinous multi-layer structures during the standard TEM sample preparation and the tilt of the cover scales, which both affect the apparent layer thicknesses in the TEM cross-sections. We proposed a simulation correction and compared the results with the layer thicknesses measured on cryogenically prepared non-embedded SEM cross-sections.