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We experimentally demonstrate ferroelectric-like non-volatile field-effect transistor (NVFET) with the amorphous Al2O3 gate insulator for artificial synapse applications. The switchable polarization (P) is attributed to the voltage modulation of mobile ions in the gate insulator. The ferroelectric-like NVFETs integrated with 3 nm and 6 nm-thick Al2O3 dielectrics demonstrate the capability to mimic various synaptic behaviors including long-term potentiation (LTP), long-term depression (LTD), and spike-timing-dependent plasticity (STDP), under different types of electrical stimuli to the gate electrode. To verify the application of the ferroelectric-like transistors in the Spike Neural Network (SNN), the online training has been carried out based on the synaptic characteristics of the devices, and a decent accuracy (>80%) is achieved for fixed-amplitude ±3 V/100 ns potentiation/depression pulses.

A self-aligned fabrication process for top-gate amorphous zinc-tin oxide (a-ZTO) thin-film transistors (TFTs) is developed, in which the source/drain (S/D) doping is realized through depositing a thin aluminum (Al) film on S/D regions and performing a thermal annealing. Results indicate that a chemical oxidation-reduction reaction between Al and a-ZTO films takes place during the thermal annealing process, and shallow donors of oxygen vacancies and metal tin (Sn) interstitials are thus generated. The formed S/D regions have a high carrier concentration over $1 \times 10 ^{20}$ cm $^{-3}$ , low sheet resistance of 0.57 k $ {\Omega }$ /sq, and high thermal stability even in oxygen ambient. The fabricated a-ZTO TFTs exhibit excellent electrical performances, including a low channel-width-normalized S/D resistance of about $7.05~ {\Omega }$ cm, a high field-effect mobility of 15.7 cm2/Vs, a high on/off current ratio of over $10 ^{8}$ , and near-zero turn-on voltage. Moreover, good electrical stability with less than 0.2-V threshold voltage shift under ±30-V gate bias stresses is also achieved.

The effects of Ti incorporation in La2O3 gate dielectric on the electrical characteristics of amorphous InGaZnO thin-film transistor are studied. Compared to the control sample with La2O3 gate dielectric, the device performance can be significantly improved with an appropriate Ti dose. Accordingly, the sample with a Ti/(Ti+La) ratio of 6.7% presents a high saturation mobility of 28.1 cm2V−1s−1, small subthreshold slope of 0.17 V/dec, large on/off current ratio of $7.2\times 10$ 7, and acceptable hysteresis. We attribute such an improvement to the passivation of the defect states at/near the La2O3/InGaZnO interface as well as the enhancement of moisture resistance of La2O3 film due to Ti incorporation. However, excessive Ti incorporation leads to device degradation, which is due to more oxygen vacancies generated in gate dielectric.

In this paper, the flicker noise properties of bottom-gate ESL structured amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) from two different technologies have been studied and modeled. Model development is carried out by adapting the Unified Model parameter Extraction Method (UMEM), developed for parameter extraction and compact modeling of TFT devices, and the unified 1/f noise model. Furthermore, comparative study of device figures of merits is performed to point out the device performance enhancements that the different fabrication technologies have brought about. It is found out that both devices have low deep state density, whereas the second device demonstrated higher performance in terms of carrier mobility and subthreshold slope. Both the DC and noise models are validated by matching them against experimental data obtained in different regimes of device operation.

The two-step implantation of argon precursor ion (Ar+) followed by boron ion (B+) in single crystalline silicon at room temperature is discussed to activate boron implanted region by post heating at 300 followed by 400°C. The implantation of Ar+ at a dose of 6.0 × 1013 cm-2 at 70 keV with a projected range Rp(Ar) of 80 nm followed by B+ at 1.0 × 1015 cm-2 and 15 keV with Rp(B) of 62 nm caused crystalline disordered states with the effective disordered amorphous depth Aeff of 32 nm, while the post heating of 300°C for 90 min followed by 400°C for 30 min markedly decreased Aeff to 1.8 nm. The effective recrystallization by the post heating promoted activation of doped region associated with decrease in the sheet resistivity to 189 Ω/sq by the post heating. The activation ratio was estimated as 0.33 under the assumption of a hole mobility of 50 cm2/Vs in the boron implanted region.

The effect of ultraviolet/Ozone (UV/O3)-assisted annealing process on the structural, chemical, and electrical properties of sol-gel-processed SnO2 films is investigated in this study. Via the UV/O3-assisted annealing processes, mixed-phase SnO2 films composed of amorphous SnO2 and polycrystalline SnO were obtained. Furthermore, the XPS spectra indicate an increase in the SnO2/SnO ratio and a substantial decrease in the number of -OH groups (serving as trap sites). This results in an increase in the conductivity and field-effect mobility of the films. The field-effect mobility of the UV/Ozone-assisted 300 °C-annealed SnO2 thin film transistor (TFT) increases considerably (by ~500×), yielding a device with a field-effect mobility of 3.09 cm2/Vs. In addition, flexible SnO2 TFTs with Al2O3 insulator and Au gate on Polyimide substrate fabricated via gate electrode engineering shows a decreased conduction bandgap offset, compared to the SnO2 TFTs on SiO2, and enhancement mode operation properties (normally off at zero gate voltage) with a field-effect mobility of 1.87 cm2/Vs.

The authors report the deposition of an (AlxGa1-x)2O3 amorphous thin film on sapphire substrates by sputter deposition. An amorphous deep ultraviolet (UV) (Al0.12Ga0.88)2O3 photodetector, with a cutoff wavelength at 230 nm, was also fabricated. With -10 V applied bias, it was found the dark leakage current and the linear dynamic range (LDR) of the fabricated photodetector were about 1.23 × 10-9 A and 59.51 dB, respectively. With the same -10 V applied bias, the UVC/UVA contrast ratio was larger than 20. With λillumination = 230 nm and -5 V applied bias, it was found noise equivalent power (NEP) and detectivity (D*) of the fabricated amorphous deep UV (Al0.12Ga0.88)2O3 photodetector were 9.94 × 10-11 W and 2.11 × 1010 cmHz1/2W-1, respectively. These results suggest the fabricated amorphous deep UV (Al0.12Ga0.88)2O3 photodetector herein indicate a cost-effective solution for developing DUV photodetector applications.

Amorphous In-Ga-Zn-O (IGZO) is a high-mobility semiconductor employed in modern thin-film transistors for displays and it is considered as a promising material for Schottky diode-based rectifiers. Properties of the electronic components based on IGZO strongly depend on the manufacturing parameters such as the oxygen partial pressure during IGZO sputtering and post-deposition thermal annealing. In this study, we investigate the combined effect of sputtering conditions of amorphous IGZO (In:Ga:Zn=1:1:1) and post-deposition thermal annealing on the properties of vertical thin-film Pt-IGZO-Cu Schottky diodes, and evaluated the applicability of the fabricated Schottky diodes for low-frequency half-wave rectifier circuits. The change of the oxygen content in the gas mixture from 1.64% to 6.25%, and post-deposition annealing is shown to increase the current rectification ratio from 105 to 107 at ±1 V, Schottky barrier height from 0.64 eV to 0.75 eV, and the ideality factor from 1.11 to 1.39. Half-wave rectifier circuits based on the fabricated Schottky diodes were simulated using parameters extracted from measured current-voltage and capacitance-voltage characteristics. The half-wave rectifier circuits were realized at 100 kHz and 300 kHz on as-fabricated Schottky diodes with active area of 200 μm × 200 μm, which is relevant for the near-field communication (125 kHz - 134 kHz), and provided the output voltage amplitude of 0.87 V for 2 V supply voltage. The simulation results matched with the measurement data, verifying the model accuracy for circuit level simulation.

A switchable polarization beam splitter utilizing GST-on-silicon waveguides is introduced and comprehensively investigated in this paper. Based on the phase matching and mode hybridization, structural parameters of the presented device are optimized by using the particle swarm optimization algorithm and finite difference time domain method, so that the output fundamental transverse-electric (TE0) and transverse-magnetic (TM0) modes can be switched by controlling the phase state of GST and the device exhibits broad bandwidth, low crosstalk, and high polarization extinction ratio. For the designed device with the amorphous GST, the crosstalk is lower than −23.40 dB and the polarization extinction ratio is larger than 21.35 dB over the C-band. In the case of the crystalline GST, within the C-band, the crosstalk of less than −27.37 dB and the polarization extinction ratio of greater than 21.37 dB are achieved.

The power losses in high power-density motors due to high rotational speed and/or high pole counts may be reduced adopting metal amorphous nanocomposites (MANCs) featuring low power loss and a relatively high flux density ($\sim$1.3 T). We recently proposed a flux switching permanent magnet (FSPM) motor with a rating of 2.5 kW at 1400 Hz electrical speed that incorporates low loss (

This paper presents the experimental results of laser-induced phase changes in chemically bath deposited (CBD) Sb2S3 films on fused silica glass substrates. The CBD allows conformal coverage of the glass substrate with surface roughness of 21.8 nm as estimated from AFM. As deposited Sb2S3 films show an amorphous-like structure as was revealed by both green laser (λex=514 nm) Raman and FT Raman (λex=1064 nm) spectroscopy. Optical transmittance indicates that the absorption edge in Sb2S3 films is 550 nm and therefore light below this wavelength will be strongly absorbed. Above certain threshold power, 2mW, of green laser (λex=514 nm) we observe that we can trigger an amorphous to crystalline phase transition in Sb2S3 films. Following this transition, we have also observed the appearance of α-Sb2O3 and the metallic Sb in the Sb2S3 films. The changes in optical properties have been investigated by spectroscopic ellipsometry.

We report characteristics of reconfigurable field effect transistors (FETs) fabricated on locally grown Si epilayer on amorphous SiO 2 . The present devices show ideal electrical properties, i.e., flexible change from n-type to p-type FET or vice versa according to the polarity of gate bias. Besides current-voltage features under various operation conditions, the effect of geometrical structure like spacing between control and polarity gates on drain current was investigated. We explained the measured electrical properties through the comparative studies of simulation-based charge distribution and microscopybased real dimension of the present devices.

Accurate electrical characterization of thin film transistor (TFT), requires measurement of its contact resistance. This work describes experimental extraction of contact resistance in top contact a-IGZO TFTs using a four-terminal structure. The auxiliary contact terminal is deposited adjacent to source away from the channel region and kept electrically floating leading to unperturbed device operation. A simplified transmission-line model of source contact relates the open-circuit voltage measured at the floating terminal with the total resistance of the transistor to directly give estimates of the contact resistance. Contact resistance corrected values of threshold voltage and field-effect mobility were extracted as 4 V and 3.2 cm2 V−1 s−1 respectively whereas the uncorrected values were 1 V and 2.4 cm2 V−1 s−1.

In diamond/silicon heterointerfaces fabricated by surface activated bonding at room temperature, an amorphous layer with carbon and silicon is formed in the bonding process, via atomic intermixing across the interfaces. The layer is crystallized by 1000°C annealing, forming a SiC compound.

Room-temperature bonding using 20-nm thick amorphous Si films was studied as a function of waiting time t w in vacuum of 1.0 × 10−6 Pa between film deposition and bonding. Bonding strength decreased suddenly at t w greater than 3.6 × 103 s, which differed from behavior observed using Ti films.

The electronic transport properties of amorphous In$_{2} \mathrm{O}_{3}(\mathrm{a} - In _{2} \mathrm{O}_{3})$ are investigated from first principles simulations for BEOL transistor application. It is determined that local atomic and electronic structure disorders in a-In 2 O 3 are the fundamental origin of reduced mobility in amorphous phase. Medium range order In-In connectivity is responsible for the electron conduction pathway. It is found that amorphous disorder present in a-In 2 O 3 could induce shallow donor states and acceptor states that are responsible for the device threshold voltage instability. Nonstoichiometric defects including indium vacancy and interstitial will further increase the density of these defect states intrinsic to a-In 2 O 3 . The results could provide a better understanding of the electronic transport behavior in a-In 2 O 3 and useful insights for future defect controlling for better device performance.

An energy efficient dual-WO 3 electrode was fabricated for electrochromic window application. A vapor-coated WO 3 was prepared using the sputtering deposition method, and a wet-coated WO 3 film was prepared with the wet chemical reaction process. The WO 3 was amorphous crystalline. The intercalated charge of the electrode with a dual-WO 3 layer was 0.0265 C/cm2. High contrast ratio of 55.8% and fast responses of 6 s for charge intercalation and 1.8 s for deintercalation were achieved.

Organic semiconductor devices promise cost-efficient processability at low temperatures, but the usually amorphous materials suffer from low charge carrier mobility. The search for high mobility organic semiconductor materials has thrived data science and Machine Learning approaches to screen the vast amount of possible organic materials. We present a multiscale simulation model based on machine learned transfer integrals to compute the charge carrier mobility in organic thin films.

An electrothermal (ET) capillary arc discharge is an effective source of high-density plasmas which can be used to evaluate high heat flux plasma impact on materials 1 . In this work, W and Mo samples were exposed to plasmas with densities between 10 19 and 10 23 m -3 , temperatures between 0.1 and 1 eV, and a mixed material composition from W/polycarbonate and Mo/polycarbonate liners. These plasma-impacted materials have been characterized using EDS, XPS, FIB, nanoindentation and refractometry in order to determine microstructure of the surface and bulk material, surface composition and sample wear behavior (strain behavior, surface roughness). The surface was confirmed to be primarily composed of metal-carbides on self-similar substrates, with trace amounts of other metals including copper from the cathode. Deposited materials showed good adhesion, with textured amorphous surfaces and grain sizes of about 50 nm. The penetration depth of ablated material and mechanical properties of the samples will be reported in detail, with early results suggesting nucleation is the primary mechanism behind surface structural organization during plasma deposition.

Transition metal dichalcogenides (TMDs) such as MoS 2 have emerged as promising candidates for replacement of Pt-based catalysts for HER. However, the poor conductivity of TMDs hinders the electron-transfer process and thus limit the HER performance. Assembling TMDs with conductive supports such as graphene has been demonstrated as an efficient way to improve HER performance. Furthermore, compared with its crystalline counterpart, amorphous molybdenum sulfide (a-MoS x ) is believed to possess better activity toward HER. Up to now, some preparation methods have been proposed to synthesize a-MoS x , including electrochemical deposition, wet-chemical synthesis and thermolysis. However, these synthesis approaches still suffer from one or more of the following drawbacks, such as solvent toxicity, high- temperature processing and time- and labor-consuming. A strategy that overcomes all of the above-mentioned problems is still highly desirable.

In this study, the impact of SiOF on the 2nd harmonic (H2) of TC-FBAR was investigated. TC-FBARs with SiOFs as temperature compensation material on the outside of the electrodes were fabricated, and their H2 were measured. The measured H2 were very different from that of the standard FBAR consisting of electrodes and piezoelectric AlN, and it is confirmed that the SiOF has a strong impact on the H2 of the TC-FBAR. As a result of comparing the simulated H2 with the measured H2, we confirmed the existence of the strong second-order nonlinearity in elasticity in SiOF.

We demonstrate the impact of the intermediate hydrogen plasma treatment of intrinsic amorphous silicon layer in silicon heterojunction solar cells (SHJ). After deposition of the first layer of intrinsic amorphous hydrogenated silicon with a thickness of 5–6 nm hydrogen plasma treatment allows passivation of defects in the layer and, due to surface hydrogenation, creates conditions for defect-free growth of the next layer to a total thickness of 10 nm. The lifetime of minority charge carriers increases from 2 to 5 ms in comparison with base process. The parameters of hydrogen plasma treatment are determined, which makes it possible to increase the surface passivation quality by the layers of intrinsic hydrogenated amorphous silicon in the production of high-efficiency solar cells. The process is useful for fabrication of high performance SHJ solar cells.

Zeolite supported nanostructured Ni and Co catalysts were synthesized at ambient conditions by cation-exchange reaction followed by a reduction of the adsorbed ions by NaBH 4 . Using UV-vis spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy it was concluded that obtained products contained up to 3 wt. % of metal catalysts while the formed metallic nanoparticles were evenly distributed at the surface of the zeolite granules. Kinetics of hydrolysis of NaBH 4 in presence of Ni and Co based catalysts has been characterized and related to the rate of hydrogen generation. Using both amorphous and zeolite supported Ni and Co nanocatalysts leads to a stable generation of hydrogen in wide range of NaBH 4 concentrations and results in high extent of its conversion. Both amorphous and zeolite supported Ni and Co allow achieving a fast kinetics of hydrogen evolution, even though synthesized “in situ” amorphous Ni and Co showed a performance which was 25 % superior as compared to the catalysts deposited on zeolite. In combination with the high stability of the obtained nanocatalysts this suggests a potential of their application in the systems for hydrogen generation.

A sample of amorphous AlBN was generated using first-principles molecular dynamics simulations. Pair correlation functions, phonon spectra, stress-shear strain relation and elastic moduli of the sample were studied.

This work presents a comparative analysis of the chemical and phase composition, current efficiency, and microhardness of binary and ternary electrolytic CoRe and CoWRe alloys, deposited from two types of electrolytes: acidic citrate and alkaline citrate-pyrophosphate ones. It has been shown that the use of electrolytes of various complexes compositions makes it possible to vary the amount of rhenium in the coatings over a wide range (12 – 59 at.%). Ternary CoWRe alloys contain 4 – 9 at.% of tungsten, and they are deposited with higher current efficiency (up to 86%) than binary alloys. By selecting the composition of the electrolyte and the electrolysis mode, it is possible to regulate not only the chemical composition but also the structure of the coatings and to obtain X-ray amorphous or crystalline alloys, depending on the task.

Structure, optoelectronic and mechanical properties of plasma-enhanced chemical vapor deposited silicon carbon nitride (Si-C-N) films at negative substrate biases U d = – 5 V and – 250 V and annealed at $600^{\circ}C, 800^{\circ}C$, and 1000°C were investigated. All the deposited and annealed films are found to be X-ray amorphous. The as-deposited films at low and high U d demonstrate one-and two-band photoluminescence, with the band maxima at 535 nm and at 560 nm, 640 nm, respectively. The hardness of the films increases with substrate bias from $\sim15$ GPa to $\sim37$ GPa. Annealing of the films obtained at low U d shifts the PL band towards long wavelengths. For the films obtained at high U d the PL band with a maximum at 560 nm shifts towards low wavelengths, and the band with a maximum at 640 nm shifts to the long-wavelength region. Annealing at $1000^{\circ}C$ in both cases leads to a quenching of PL. Si-C-N films deposited at low U} d demonstrate a slight decrease in the mechanical proporties with annealing, which indicates their thermal stability. Whereas, the high-biased Si-C-N films demonstrate a significant decrease of hardness even at low annealing temperatures.

A study of phase structure in (TiZrHfNbV)N coatings irradiated with 200 MeV high energy Xe14+ ions with different fluences was carried out. Although (TiZrHfNbV)N coatings were irradiated with high energy Xe+ ions with different fluences: $5 \times 1011(5\mathrm{E}11)$, $5 \times 1012(5\mathrm{E}12)$ and $5 \times 1013(5\mathrm{E}13)$ ions/cm2, no amorphous or intermetallic phase are detected.

In this paper, the mechanical behavior of silicon nanowires with the hollow-core geometry was investigated using molecular dynamics simulation. The pristine Si nanowires are considered as references to compare the mechanical properties of the hollow-core structures. Our results show that hollow-core silicon nanowires with a cavity volume fraction above 50% have a larger fracture strain compared to nanowires with a smaller cavity. Under uniaxial tensile loading, the computed Young’s modulus decreases as the radius of cylindrical cavity in nanowire increases. To understand the mechanical behavior of hollow-core Si nanowires, the structural evolution of the nanowire with different cavity volume fraction was investigated. It is established that the structure of nanowires with a cavity volume of more than 50% is completely amorphous. We have shown that structural changes in nanowires are the root cause of changes in their mechanical behavior.

This letter reports on the performance of LiTaO 3 based pyroelectric single-element detectors coated with a nanos-tructured thin-film absorber consisting of the NiCr material as the sensor electrodes. Goldblack film have been proven to be an effective absorption layer for pyroelectric detectors. Improving the absorption can be achieved by adjusting the surface characteristics of goldblack film. Goldblack coatings are low-density amorphous deposits of gold that appear black in the visible and infrared regions of the electromagnetic spectrum. They have absorption close to unity for radiation in this range. Because of the delicate nature of the coatings, they are easily crushed or displaced by touch or even blasts of air, their use has not been extensively exploited but rather the process is re-invented every time a specific requirement appears. This is typified by our requirement to coat a small pixel pyroelectric detector.

SmartFilms® loaded with different amounts of indomethacin (IM) were prepared, compressed into tablets and investigated using THz TDS in transmission geometry. Corresponding physical mixtures were also prepared, transferred into tablets and investigated. Furthermore, complementary x-ray diffraction (XRD) measurements were performed. The results suggest that IM loaded in smartFilms was kept in its amorphous state for the lowest loading and recrystallized for higher loadings.

In this work, Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) were fabricated on cellulose microfiber paper substrate. Silver lines used as the Schottky barrier were printed, in parallel to thermally evaporated Cr/Au ohmic contact, using a dispense printer. The morphological and electrical characteristics of the devices are presented. The fabricated diodes exhibited rectification ratios ranging from 3.4 to 34.9 at ±1V with ON voltages that range from 1.1V to 1.4 V, for device lengths (Ag to Au distance) from 145 µm to 894 µm. The diodes were characterized in a temperature range between 25°C and 80°C. They showed a decrease of the ON current when increasing temperature, which is mainly attributed to the change of the cellulose microstructure. Indeed, an opposite of the ON current behavior was registered when the diode was realized on a polyimide substrate. The realized flexible paper-based diodes offer a potential promising choice for printed environmental-friendly electronics.

Gate insulators (GI) with high dielectric constant (high-k) ensure high performance and low voltage operation of oxide thin-film transistors (TFT) such as amorphous InGaZnO (a-IGZO). Here, we report that the combination of BaTit), (BTO) nanoparticles (NP) and polysiloxane (PSX) hybrid organic-inorganic material can effectively form a high-k GI at low temperatures. By optimizing the ratio between the BTO NP and the PSX polymer matrix, high mobilities of up to ~30 cm2/Vs can be realized with low leakage currents. In this paper, we analyzed both the temperature and thickness dependence of the performance and leakage current of a-IGZO TFTs with high-k hybrid GI having a high BTO NPratio.

We investigated electron transport properties of an argon ion (Ar+) implanted a-IGZO film on glass by Hall measurement combined with wet etching. As a result, we obtained concentration and mobility of electron as a function of depth in the a-IGZO from the surface, and high concentration area in depth distributed deeper compared with one of the argon plasma treated a-IGZO. In addition, we estimated the implanted Ar atom and oxygen vacancy depth-profiles in the a-IGZO. We confirmed Ar stopping powers of a-IGZO and the donor level of 0.05-0.1 eV below bottom of conduction band energy, which can be applied to resistance control technique for a-IGZO device processes.

Most of the exhaust heat generated from factories, automobiles, PCs, etc. is unused. Thermoelectric conversion devices are attracting attention as a clean power generation method because they can convert thermal energy into electrical energy. As examples of thermoelectric materials, BiTe is researched as high-performance material. However, BiTe contains rare metals. Moreover, transparent and flexible thermoelectric materials can be applied to power generation using window glass and IoT sensors. Therefore, we are researching thin film thermoelectric conversion devices using GTO thin films which are transparent, flexible and rare metal-free oxide semiconductors. In this study, the GTO thin film thermoelectric conversion element was fabricated using an RF magnetron sputtering method. A polycrystalline thin film and an amorphous thin film were formed, and atmospheric annealing was performed on each of them. The conductivity of both the polycrystalline thin film and the amorphous thin film was improved up to an annealing temperature of 200°C. The power factor also reached the maximum value when the annealing temperature was between 100°C and 200°C.

In this work, using coal as raw materials (RC), which is one of the cheapest natural carbon sources and most abundant, and converted to coal-based carbons (CBC) by catalytic activation followed with Low temperature graphitization, the XRD, Raman spectroscopy, SEM, and TEM/FFT results confirmed the structural transformation from amorphous to the crystalline structure. The electrochemical performance was investigated using electrochemical methods, (CBC) anode delivered stable charge/discharge capacities compared with the (RC) anode, and stable cycle life of 243 mAh g-1 can be acquired after 100 cycles with a coulombic efficiency over 98 % at 0.2C current density; this attributed to the contributions of the porous and crystalline structure, considering the low cost, easy preparation, and good performance, the coal-based carbons can be a good candidate instead of graphite as the anode materials of lithium-ion batteries (LIBs).

Silk fibroin is a promising host biomaterial for the development of the forthcoming generation of wearable opto-electronic devices [1] ; also exhibiting interesting sensing functionalities [2] . Silk fibroin undergoes a unique structural transformation from the Silk I (amorphous) to the Silk II (semi-crystalline) structure; this transformation is accompanied by a number of distinct changes in the physical (i.e., wettability) and optical (birefringence) properties of this biomaterial, while being underlined by the augmentation of nano-crystalline β-sheet structures occurring in the Silk II structure.

Third harmonic generation (THG) from multiple thin layer structures has proven its capability to reach conversion efficiencies up to the percentage level [1] , becoming an interesting alternative to the cascaded third harmonic generation. However, such multi-layer structures need to be carefully optimized by computer algorithms. Here, we present a study of a single amorphous Hf x Al y O z layer with varying thickness. The advantage of ternary mixture materials such as Hf x Al y O z is the tunability of the bandgap, which directly influences the nonlinear susceptibility χ (3) . In comparison to previous works, where only layers of specific thickness or theoretical models were studied [2] , [3] , we present both, continuous experimental measurements and theoretical studies of the same sample.

Thermally tunable optical metasurfaces based on chalcogenide phase-change materials (PCMs) - whose refractive indices between their amorphous and crystalline phases can be abruptly controlled via optical, electrical or thermal heat stimuli - are currently one of the most promising approaches towards the creation of novel, compact, and fast reconfigurable nanophotonic devices. Yet, such a technology currently faces various non-trivial technological and engineering challenges that need to be overcome before implementing them in real-world applications [1] . One of the most critical aspects for PCM metasurfaces to be successful is the achievement of in-situ electrical switching without severely compromising the optical performance. For this purpose, good electrical conductors (metals) with high melting points (i.e. above the melting point of GeSbTe based alloys where T melt ~ 630 ᵒC) are required to avoid long-term degradation. In addition, such metallic elements suffer from thermally activated atomic diffusion into PCMs and/or semiconductors such as Ge 2 Sb 2 Te 5 (GST) or silicon, which results in the creation of parasitic interfacial gold/silver tellurides and gold/silver silicides that can catastrophically and irreversibly degrade device optical performance [2] , leading to unreliable device designs.

Three-dimensional control in the tuning of the linear and nonlinear properties of optical materials can catalyse the design of new photonic devices. Glasses being the backbone materials for drawing optical fibres, are inherently centrosymmetric, so their nonlinear dielectric susceptibility χ (2) is zero; thermal poling has been used for breaking the symmetry of such amorphous matrixes [1] .

International audience; Irradiation of crystalline silicon with ultrashort laser pulses is a well-known method for creating thin amorphous surface layers. The underlying mechanisms are based on ultrafast melting and rapid quenching of the molten phase, preventing the formation of the crystalline phase. The interest of this method for applications in the electronics industry lies in the very different electrical properties of the amorphous phase obtained. It has also triggered strong attention in the field of silicon photonics, the amorphous phase exhibiting a higher refractive index than the crystalline phase at telecom wavelengths. This simple feature could be exploited for low-loss optical waveguiding in a thin amorphous surface layer, provided the latter is sufficiently thick. However, the maximum thickness of laser-induced amorphous layers reported to date is < 70 nm [1] , which is below the requirements for supporting guided modes.

Spectral hole burning in rare earth doped crystal can provide frequency references based on the optical transition of the dopant ions [1] . The narrow spectral patterns can be used to improve laser frequency stabilization [2] , [3] and provide a new generation of ultra-stable lasers with lower thermal noise benefiting from the cryogenic environment and better quality factor of the crystal than the amorphous glass typically used in the Fabry-Perot cavity. We utilize Europium doped yttrium silicon oxide (Eu:YSO) in our experiments, which allow realization of long lived (hours or more depending on temperature) narrow spectral holes ( kHz or less) well suited for high precision experiment applications. We will describe our novel double-heterodyne detection method [4] , used to decrease the detection noise, as well as experiments assessing quantitatively the sensitivity of the spectral pattern to crystal deformation [5] , [6] , application of electric field [7] and temperature fluctuations. We currently demonstrate a state-of-the-art laser frequency stability at 1.7 × 10 − 15 at 1s [4] , limited by the latter effect, for which improvement strategies have been demonstrated elsewhere [2] and which we are currently implementing. The other effects which we have quantitatively studied are compatible with a few 10 − 18 frequency stability at 1s time scale. This work is particularly promising in the context of optical frequency lattice clocks, for which the ultra-stable laser used for probing the clock transition is a strong limiting factor of the frequency stability.

The wide bandgaps and superior conductivity of ZnS x Se 1–x semiconductors to amorphous Si suggest an alternative carrier-selective contact in silicon heterojunction solar cells. Electron-selective ZnS x Se 1–x front contacts on p-type c-Si solar cells are explored by simulating in Sentaurus TCAD a large design parameter space informed by experimentally determined optoelectronic properties. Comparable performance to experimental and simulated p-SHJ reference devices is shown, with a champion simulated device efficiency of 20.8%.

Over decades, the electrical properties of metal oxides have been a myth, stimulating rigorous debate and research. It is commonly accepted that the oxygen vacancy, working as shallow donors, gives rise to the n-type semiconductor behavior in these metal oxides. However, the function of the oxygen vacancy has been doubted, the energy level of which is reported to be far below conduction band to be responsible for the n-type conductivity [1] . In addition, metal oxides with oxygen deficiency in nature is susceptible to the spurious oxidation from the environment, resulting in stability and reliability issue in electronic device. In this work, we observe the conductivity transition from insulator to semiconductor of the stoichiometric TiO 2 films via judicious control of the crystallinity, highlighting the important role of crystallinity in the electrical properties of metal oxide. Based on this observation, high-performance thin film transistors (TFTs) with polycrystalline TiO 2 (poly-TiO 2 ) as the active channel and InAlN/GaN metal-insulator-semiconductor high-mobility-electron-transistors (MISHEMTs) with amorphous TiO 2 (a-TiO 2 ) as the gate dielectrics are demonstrated, indicating the full potential of stoichiometric TiO 2 films as functional electronic materials in device applications.

a-Si/c-Si heterojunction solar cells hold the efficiency world record around 27%, yet their market penetration is delayed. One concern is the presence of an amorphous Si layer that some suspect may speed up the degradation of their performance. To address this concern, we developed the SolDeg structural simulation platform that is capable of capturing extremely slow degradation processes in a-Si. SolDeg integrates molecular dynamics methods that optimize the Si structure with femtosecond time steps, with the nudged elastic band method that captures the defect generation on time scales extending to gigaseconds. In this paper we report SolDeg simulations for Si-only heterojunctions. The SolDeg platform enabled us to determine the defect generation rate to be in the 15-20%/year range, translating into a 1-1.5%/year Voc degradation rate. These results establish that SolDeg can be a uniquely useful platform to describe degradation processes with an eye on finding strategies to mitigate the performance degradation of these promising heterojunction cells.

CuIn (1−x) Ga x Se 2 (CIGS) photovoltaics have limited market success due to high capital costs largely attributed to a slow, high-temperature deposition procedure. To reduce such costs we show that a high-rate, low-temperature approach including a short recrystallization step using metal halides can dramatically increase grain size in CIGS. We have demonstrated this both with high-rate evaporated films and amorphous films sputtered at room temperature. Both approaches can greatly increase throughput and reduce the costs of CIGS deposition. We review previous results for a number of metal halides and specifically focus on InCl 3 and AgBr as the most promising. We show that using high-temperature x-ray diffraction that crystallization begins at 270°C and ends at 380°C and is greatly accelerated by the metal halides, resulting in much larger grains over the same temperature range.

We report on the optoelectronic and structural properties of MoO 3-x thin layers deposited by reactive DC magnetron sputtering, of a pure Mo target under different oxygen to total flow ratios [r(O 2 ) = O 2 /Ar, ranging from 0.25% to 16%]. Structural, morphological, optical and electronic transport analyses were systematically carried out on the deposited films. Transmission electron analysis showed that the films are compact and amorphous for low r(O 2 ) and porous and crystalline for high O-content (i.e. 8 and 16 %). The associated hole mobilities were found to vary by almost two orders of magnitudes with respect to r(O 2 ), and reached the very high value of ~20 cm2/Vs for 0.08 of oxygen. Correlations between optical transmittance/absorbance, oxidation states, different refractive indexes and the oxygen content are also presented and discussed.

Gallium nitride (GaN) high-electron-mobility transistor (HEMT) and vertical GaN metal-oxide-semiconductor (MOS) devices have potential application to high power and high frequency because of their superior characteristics, such as wide band gap (B g ), high electron saturation velocity, and a high critical breakdown voltage [ 1 – 3 ]. Gate insulator plays an important role to suppress the leakage current in both GaN HEMT and GaN MOS devices. Various materials such as SiO 2 , Al 2 O 3 , HfO 2 , AlSiO x , and HfSiO x have been widely investigated as gate insulator, and films of these materials are typically deposited via chemical vapor deposition or atomic layer deposition (ALD) [ 4 – 10 ]. Figure 1 shows the relationship between dielectric constant ( k ) and B g of candidate gate insulators [11] . The B g generally decreases as the k value increases. HfO 2 is known to have a high k value but crystallization temperature is as low as 400°C. Al 2 O 3 starts to crystalize around 700°C. On the other hand, silicate materials such as AlSiO x and HfSiO x have a more stable amorphous structure at 800°C and expect to suppress the leakage current. Here, AlSiO x and HfSiO x films were formed by a two-step process such as film formation of (Al 2 O 3 ) m /(SiO 2 ) n and (HfO 2 ) m /(SiO 2 ) n nanolaminate structures using ALD, respectively, and post-deposition annealing (PDA) treatment.

In this work, the magnetoelastic resonance behaviour has been studied in amorphous metallic ribbons and microwires using a custom-made setup. First, optimal setup conditions were determined for both devices, then the frequency shift dependence on polymer mass deposition was studied. Both devices show a predictable response to the mass deposition of the polymer tested, making them suitable for contactless chemical sensors.

Electrical stability and flicker (1/f) noise of thin-film heterojunction field-effect transistors (HJFETs) comprised of hydrogenated amorphous Si (a-Si:H) gate and hydrogenated crystalline Si (c-Si:H) source and drain regions on small-grain poly-Si substrates are investigated and benchmarked against conventional thin-film transistors (TFTs). Despite the low growth temperature of a-Si:H and c-Si:H (~200°C), HJFETs are found to have higher stability and lower flicker noise than conventional TFTs. These results may be attributed partly to the device structure and partly to the high-quality gate heterojunction of the HJFETs.

Amorphous IGZO thin-film transistors (TFTs) in an etch stop layer (ESL) structure was processed on 2500 mm $\times $ 2200 mm size substrate. The fabricated devices exhibit enhancement mode characteristics, and excellent uniformity over large area. The presented good operational stabilities under both positive gate bias temperature stress (PBTS) and negative gate bias temperature stress (NBTS) tests can well meet the requirements for pixel switching. However, considering even threshold voltage shift under long term positive bias stress might affect proper operation of the gate driver on array (GOA), a design with a pulse gating scheme is proposed, consisting of 13 TFTs and 1 capacitor, to avoid long term continuous bias stressing of the TFT. With the proposed GOA design, a 32-inch QUHD ( $7680\times 4320$ ) high-resolution liquid crystal display (LCD) panel with a 7 mm wide bezel is achieved. The reliability of the GOA circuit is well proved through standard aging tests.