Solid Phase Crystallization Research Articles

High-electron mobility P-doped polycrystalline GeSn layers formed on insulators at low temperatures

Despite its long history, synthesizing n-type polycrystalline Ge layers with high-electron mobility on insulating substrates has been difficult. Based on our recently developed solid-phase crystallization technology, here, we have demonstrated the highest recorded electron mobility (450 cm2 V−1 s−1) for Ge-based polycrystalline thin films on insulating substrates. The underlayer type and small amount of Sn addition were the key parameters controlling both the density and barrier height of the grain boundaries in the P-doped polycrystalline Ge layers. The low growth temperature (≤400 °C) allowed us to develop a GeSn layer on a heat-resistant polyimide film, which exhibited the highest electron mobility (200 cm2 V−1 s−1), as a semiconductor thin film synthesized directly on a flexible substrate. These achievements herald the development of high-performance polycrystalline Ge-based devices on inexpensive glass and flexible plastic substrates.

Solid-liquid phase equilibrium for the system ammonium polyphosphate-urea ammonium nitrate-potassium chloride-water at 273.2 K

Based on the dynamic method, a quaternary system of ammonium polyphosphate (APP)-urea ammonium nitrate (UAN, CO(NH2)2-NH4NO3)-potassium chloride (KCl)-H2O and its subsystems (APP-[CO(NH2)2-NH4NO3]-H2O, KCl-[CO(NH2)2-NH4NO3]-H2O and APP-KCl-H2O) were systematically investigated at the temperature of 273.2 K. Each ternary phase diagram contains one invariant point and three crystallization regions. The crystallization regions are: (1) (NH4)3HP2O7, (NH4)4P2O7 and ((NH4)3HP2O7 + (NH4)4P2O7) for APP-[CO(NH2)2-NH4NO3]-H2O diagram; (2) KCl, KNO3 and (KCl + KNO3) for KCl-[CO(NH2)2-NH4NO3]-H2O diagram and (3) (NH4)3HP2O7, KCl and ((NH4)3HP2O7 + KCl) for APP-KCl-H2O diagram. The quaternary phase diagram of APP-[CO(NH2)2-NH4NO3]-KCl-H2O has no quaternary invariant point but includes four solid phase crystallization regions, i.e., (NH4)3HP2O7, (NH4)4P2O7, KNO3 and KCl, in which the KNO3 region occupies the largest area. The maximum total nutrient content (N + P2O5 + K2O) existing as ionic forms in the APP-[CO(NH2)2-NH4NO3]-H2O, KCl-[CO(NH2)2-NH4NO3]-H2O, APP-KCl-H2O and quaternary systems is 44.70%, 32.86%, 45.56% and 46.23% (mass), respectively, indicating that the maximum nutrient content can be reached using raw materials of the corresponding systems to prepare liquid fertilizer. In the quaternary system, the content of NH4+-N ascends with the increase of the total nutrient content, while the contents of NO3--N and CO(NH2)2-N increase with elevated total N. This work can help optimize the operating parameters for the production, storage and transportation of liquid fertilizers.

Fluorination Enables Dual Ferroelectricity in Both Solid- and Liquid-Crystal Phases.

Ferroelectric materials are a special type of polar substances, including solids or liquid crystals. However, obtaining a material to be ferroelectric in both its solid crystal (SC) and liquid crystal (LC) phases is a great challenge. Moreover, although cholesteric LCs inherently possess the advantage of high fluidity, their ferroelectricity remains unknown. Here, through the reasonable H/F substitution on the fourth position of the phenyl group of the parent nonferroelectric dihydrocholesteryl benzoate, we designed ferroelectric dihydrocholesteryl 4-fluorobenzoate (4-F-BDC), which shows ferroelectricity in both SC and cholesteric LC phases. The fluorination induces a lower symmetric polar P1 space group and a new solid-to-solid phase transition in 4-F-BDC. Beneficial from fluorination, the SC and cholesteric LC phases of 4-F-BDC show clear ferroelectricity, as confirmed by well-shaped polarization-voltage hysteresis loops. The dual ferroelectricity in both SC and cholesteric LC phases of a single material was rarely found. This work offers a viable case for the exploration of the interplay between ferroelectric SC and LC phases and provides an efficient approach for designing ferroelectrics with dual ferroelectricity and cholesteric ferroelectric liquid crystals.

Study on Stable Phase Equilibria of Quinary System LiBr–NaBr–KBr–MgBr2–H2O at 298.15 K

According to the composition characteristics of mineral elements in underground brine in the Sichuan basin of China, the complete phase equilibria and phase diagram of the quinary system LiBr–NaBr–KBr–MgBr2–H2O were studied at 298.15 K. Using the experimentally determined solubilities and equilibrium solids, the spatial stereo phase diagram of the quinary system, the dry base projection phase diagrams of the saturated surfaces of the four salts MgBr2·6H2O, KBr, LiBr·2H2O, and NaBr·2H2O, and the corresponding water content diagrams were plotted, respectively. The experimental results show that at 298.15 K, in addition to the four original components, the anhydrous salt NaBr and the double salt KBr·MgBr2·6H2O are formed. The phase diagram of the quinary system at 298.15 K contains 10 univariate curves, three invariant points, and six equilibrium solid-phase crystallization regions (KBr crystallization region, NaBr crystallization region, NaBr·2H2O crystallization region, MgBr2·6H2O crystallization region, LiBr·2H2O crystallization region, KBr·MgBr2·6H2O crystallization region). When MgBr2·6H2O or KBr is saturated, LiBr has a strong salting-out effect on KBr, NaBr, or MgBr2 and NaBr, while when LiBr·2H2O is saturated, MgBr2 has a salting-out effect on KBr and NaBr. All four saturated projection surfaces have MgBr2·6H2O, and NaBr is generated. These phase equilibrium data can provide a theoretical basis to guide underground brine mining and extract useful components.

Critical-like behavior of low-frequency dielectric properties in compressed liquid crystalline octyloxycyanobiphenyl (8OCB) and its nanocolloid with paraelectric BaTiO3

The report presents pressure-related broadband dielectric spectroscopy (BDS) studies in liquid crystalline octyloxycyanobiphenyl (8OCB) and its nanocolloid with BaTiO3 paraelectric nanoparticles. It is focused on the low-frequency (LF) domain, and the impact of pretransitional fluctuations. Studies were carried out in isotropic liquid, nematic, Smectic A, and solid crystal phases. In each case, the critical-type behavior for the LF contribution to the real part of dielectric permittivity and DC electric conductivity is evidenced. Studies of dielectric constant, related to the static frequency domain, revealed in SmA mesophase the shift from the XY-type to the mean-field type criticality when adding nanoparticles. The ‘giant’ premelting effect, with the critical-like portrayal, in the solid crystal phase, is also evidenced. Studies are supplemented by the polarizing microscopy insight into all tested phases appearing on compressing in 8OCB, and the nanocolloid. Photos show prenematic fluctuations in the isotropic liquid phase, phase transitions, changes within nematic and smectic mesophases on compressing, and the impact of nanoparticles.

Solid-liquid equilibria in relevant subsystems of LiBr-NaBr-KBr-MgBr2-CaBr2-H2O system at 298.15K.

In view of the composition characteristics of lithium, calcium and bromine rich in Nanyishan oil and gas field brine of western Qaidam Basin, Qinghai Province, as well as based on the results reported in relevant literature, the phase equilibrium relationship of ternary system LiBr-CaBr2-H2O at 298.15K was studied by isothermal dissolution equilibrium method. The equilibrium solid phase crystallization regions, as well as the compositions of invariant point, in phase diagram of this ternary system were clarified. On basis of the above ternary system research, the stable phase equilibria of quaternary systems (LiBr-NaBr-CaBr2-H2O, LiBr-KBr-CaBr2-H2O and LiBr-MgBr2-CaBr2-H2O), as well as quinary systems (LiBr-NaBr-KBr-CaBr2-H2O, LiBr-NaBr-MgBr2-CaBr2-H2O and LiBr-KBr-MgBr2-CaBr2-H2O) were further carried out at 298.15K. According to the above experimental results, the corresponding phase diagrams at 298.15K were drawn, which revealed the phase relationship of each component in solution and the law of crystallization and dissolution, and meanwhile summarized changing trends. The research results of this paper lay a foundation for further research on the multitemperature phase equilibria and thermodynamic properties of lithium and bromine containing high-component brine system in later stage, and also provide basic thermodynamic data for guiding the comprehensive development and utilization of this oil and gas field brine resource.

Single-shot selective femtosecond and picosecond infrared laser crystallization of an amorphous Ge/Si multilayer stack

Pulsed laser crystallization is an efficient annealing technique to obtain polycrystalline silicon or germanium films on non-refractory substrates. This is important for creating “flexible electronics” and can also be used to fabricate thin-film solar cells. In this work, near- and mid-infrared femtosecond and picosecond laser pulses were used to crystallize a Ge/Si multilayer stack consisting of alternating amorphous thin films of silicon and germanium. The use of infrared radiation at wavelengths of 1030 and 1500 nm with photon energies lower than the optical absorption edge in amorphous silicon allowed obtaining selective crystallization of germanium layers with a single laser shot. The phase composition of the irradiated stack was investigated by the Raman scattering technique. Several non-ablative regimes of ultrashort-pulse laser crystallization were found, from partial crystallization of germanium without intermixing the Ge/Si layers to complete intermixing of the layers with formation of GexSi1-x solid alloys. The roles of single- and two-photon absorption, thermal and non-thermal (ultrafast) melting processes, and laser-induced stresses in selective pico- and femtosecond laser annealing are discussed. It is concluded that, due to a mismatch of the thermal expansion coefficients between the adjacent stack layers, efficient explosive solid-phase crystallization of the Ge layers is possible at relatively low temperatures, well below the melting point.

N-Type Polycrystalline Germanium Layers Formed by Impurity-Doped Solid-Phase Growth

The carrier mobility of polycrystalline Ge thin-film transistors has significantly improved in recent years, raising hopes for the realization of next-generation electronic devices. Here, we adapted advanced solid-phase crystallization, which achieved the highest hole mobility of the polycrystalline semiconductor layer, to Ge layers doped with n-type impurities (P, As, and Sb). The type and amount of dopants had marked effects on the growth morphology and electrical properties of the Ge layers because they altered the activation energies in crystal growth, dopant activation rates, and grain boundary properties. In particular, P doping was effective in increasing the grain size (25 μm) and lowering the grain boundary barrier height (20 meV), which improved the electron concentration (8.0 × 1018 cm–3) and electron mobility (380 cm2 V–1 s–1) in n-type polycrystalline Ge layers. The electron mobility is greater than that of most semiconductor layers synthesized at low temperatures (≤500 °C) on insulators, and this will pave the way for advanced electronic devices, such as multifunctional displays and three-dimensional large-scale integrated circuits.

Crystallization characteristics of Li2O–Nb2O5 compound films on sapphire substrates and formation of crack-free and thick LiNbO3 epitaxial films

The formation of crystal phases in Li 2 O–Nb 2 O 5 compound films deposited on sapphire C-plane and A-plane substrates was studied by X-ray diffraction. Sufficiently oxidized samples with Li-deficient or stoichiometric compositions were prepared by co-sputtering from LiNbO 3 (LN) and Li 2 O targets. Crystallization during deposition at elevated temperatures and solid-phase crystallization (SPC) of deposited amorphous films were investigated. For films on sapphire C-planes, nucleation into Li 3 NbO 4 (222) domains occurred at the onset temperature of crystallization. In the case of stoichiometric films, the LN(006) signal indicating epitaxial growth was the primary one for crystallization during deposition above 460 °C and SPC above 750 °C. Misoriented LN(104) domains tended to coexist with LN(006) domains. In the case of Li-deficient films, LiNb 3 O 8 (_602) domains coexisted with LN(006) at temperatures above 750 °C as a result of Li 2 O loss. For films on sapphire A-planes, epitaxial LN(110) domains were predominant. Li 3 NbO 4 (222) domains were totally absent and the signal intensity of LiNb 3 O 8 (212) was less than 10% of that of LN(110) even for the Li-deficient films, which reflected fast crystallization of LN(110) domains. The SPC rate of stoichiometric film was considerably lower than that of Li-deficient film. As-crystallized LN film on the sapphire C-plane was strained with a narrow domain width. Thick film cracked as a result of stress caused by lattice mismatch with the substrate. In contrast, LN film processed by SPC was not strained and had large domains with flat film surface. Based on these results, crack-free 1-μm-thick LN epitaxial films on a sapphire C-plane were achieved. First, an amorphous LN buffer was subject to SPC to obtain a relaxed buffer layer. Subsequently, a stress-free thick LN overlayer was grown by co-sputtering from Li 2 O and LN targets at 530 °C. The relaxed buffer layer effectively mitigated the strain caused by the lattice mismatch with the substrate.

Solid phase crystallization of amorphous silicon at the two-dimensional limit.

The epitaxy of silicene-on-Ag(111) renewed considerable interest in silicon (Si) when scaled down to the two-dimensional (2D) limit. This remains one of the most explored growth cases in the emerging 2D material fashion beyond graphene. However, out of a strict silicene framework, other allotropic forms of Si still deserve attention owing to technological purposes. Here, we present 2D Solid Phase Crystallization (SPC) of Si starting from an amorphous-Si on Ag(111) in atomic coverage to gain a crystalline-Si layer by post-growth annealing below 450 °C, namely Complementary Metal Oxide Semiconductor (CMOS) Back-End-of-Line (BEOL) thermal budget limit. Moreover, considering the benefit of the 2D-SPC scheme, we managed to write crystalline-Si pixels on the amorphous-Si matrix. Our in situ and ex situ analyses show that an in-plane interface or a lateral heterojunction between amorphous and crystalline-Si is formed. This amorphous-to-crystalline phase transformation suggests that 2D silicon may stem from an epitaxially grown layer and thermal self-organization/assembling.

Stable Phase Equilibria of the Quaternary System LiBr-NaBr-KBr-H2O and the Ternary System LiBr-KBr-H2O at 323.15 K

According to the composition characteristics of lithium, potassium, bromine, and other resources rich in the salt lake brine of the Qinghai–Tibet Plateau, the phase equilibria of the quaternary system LiBr-NaBr-KBr-H2O and its ternary subsystem LiBr-KBr-H2O at 323.15 K are studied by an isothermal dissolution equilibrium method. The solubility of each system in equilibrium solution at the corresponding temperature is measured, and the corresponding phase diagrams are drawn according to the phase equilibrium experimental data. The results show that there is no complex salt or solid solution in the ternary system LiBr-KBr-H2O at 323.15 K. The phase diagram contains one invariant point (E1), two univariate curves (AE1 and BE1), and two equilibrium solid crystallization regions (corresponding to LiBr·H2O and KBr), belonging to the simple cosaturated type. The quaternary system LiBr-NaBr-KBr-H2O also has no formation of complex salt and solid solution. The phase diagram contains two invariant points (F1 and F2), five univariate curves (E1F1, E3F1, F1F2, E2F2, and E4F2), and four equilibrium solid-phase crystallization regions (corresponding to LiBr·H2O, KBr, NaBr·2H2O, and NaBr). At the same time, to further explain the phase equilibrium relationship of each system at different temperatures and the change rule of each component, comparison and discussion are carried out.

Solid-Liquid Phase Equilibria of Quaternary System LiBr-NaBr-KBr-H2O and Its Subsystems at 348.15 K.

In view of the composition characteristics of lithium, calcium, and bromine rich in Nanyishan oilfield water of the Qaidam Basin, Qinghai Province, the phase equilibrium relationships of quaternary system LiBr-NaBr-KBr-H2O and its ternary subsystems LiBr-NaBr-H2O and LiBr-KBr-H2O at 348.15 K were studied by the isothermal solution equilibrium method, and the equilibrium solid-phase crystallization regions and composition of each invariant point in each system were determined. The results show that there is no complex salt or solid solution in ternary systems LiBr-NaBr-H2O and LiBr-KBr-H2O at 348.15 K, and the phase diagram contains only one invariant point, two isothermal univariate curves, and two equilibrium solid-phase crystallization regions. The quaternary system LiBr-NaBr-KBr-H2O also has no formation of complex salt or solid solution, and the phase diagram contains only one invariant point, three isothermal univariate curves, and three equilibrium solid-phase crystallization regions. Meanwhile, the phase equilibrium relationships and change laws of each component of the above-mentioned systems at different temperatures were compared and discussed.

Ge1−x Sn x nanodots crystal nuclei for solid phase crystallization of poly-Si1−x−y Ge x Sn y

Solid phase crystallization of polycrystalline Si1−x−y Ge x Sn y using Ge1−x Sn x nanodots (Ge1−x Sn x -ND) as crystal nuclei was examined. The effects of the substrate temperature and the ratio of the deposited Ge and Sn on the dot size, the coverage, and the substitutional Sn content in the Ge1−x Sn x -ND were investigated. Lowering the deposition temperature increased the coverage and the substitutional Sn content of the Ge1−x Sn x -ND. Crystallization of Si deposited on the Ge1−x Sn x -ND was confirmed at the deposition temperature of 150 °C. The Si content was higher when Si was deposited on nanodots with higher coverage, and the Si and Sn contents in the poly-Si1−x−y Ge x Sn y layer were estimated to be as high as 36.3% and 4.2%, respectively, after annealing at 225 °C for 30 min.

High Thermoelectric Performance in Polycrystalline GeSiSn Ternary Alloy Thin Films.

Group IV materials are promising candidates for highly reliable and human-friendly thin-film thermoelectric generators, used for micro-energy harvesting. In this study, we investigated the synthesis and thermoelectric applications of a Ge-based ternary alloy thin film, Ge1-x-ySixSny. The solid-phase crystallization of the highly densified amorphous precursors allowed the formation of high-quality polycrystalline Ge1-x-ySixSny layers on an insulating substrate. The small compositions of Si and Sn in Ge1-x-ySixSny (x < 0.15 and y < 0.05) lowered the thermal conductivity (3.1 W m-1 K-1) owing to the alloy scattering of phonons, while maintaining a high carrier mobility (approximately 200 cm2 V-1 s-1). The solid-phase diffusion of Ga and P allowed us to control the carrier concentration to the order of 1019 cm-3 for holes and 1018 cm-3 for electrons. For both p- and n-type Ge1-x-ySixSny, the power factor peaked at x = 0.06 and y = 0.02, reaching 1160 μW m-1 K-2 for p-type and 2040 μW m-1 K-2 for n-type. The resulting dimensionless figure of merits (0.12 for p-type and 0.20 for n-type) are higher than those of most environmentally friendly thermoelectric thin films. These results indicate that group IV alloys are promising candidates for high-performance, reliable thin-film thermoelectric generators.

Preparation and characterization of curcumin/β-cyclodextrin nanoparticles by nanoprecipitation to improve the stability and bioavailability of curcumin

This work, curcumin/β-cyclodextrin inclusion complex (CUR/β-CD IC) nanoparticles were successfully synthesized via flexible and efficient nanoprecipitation using absolute ethanol as precipitant. At the 1:2 and 1:1 M ratios of CUR/β-CD nanoparticles, the encapsulation efficiency reached more than 70%, and particle size was ∼200 nm. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) results validated the construction of CUR/β-CD nanoparticles. FT-IR results indicated that CUR remained in β-CD cavity, and the IC molecules aggregated to form nanoparticles via intermolecular hydrogen bonding. XRD results displayed the formation of new solid crystal phases in CUR/β-CD IC nanoparticles. As-synthesized CUR/β-CD IC nanoparticles exhibited excellent physicochemical stability compared to free CUR. Encapsulation of CUR within nanoparticles also improved its bioavailability. Therefore, nanoprecipitation is a promising approach to synthesize CD-based nanoparticles for delivery of CUR or other phytochemicals with enhanced stability and bioavailability.

High Temperature Solid Phase Crystallization of a-Si on Glass by Short Time Blue Laser Exposure for Display Backplane

We report solid-phase crystallization (SPC) of amorphous silicon (a-Si) using blue laser annealing (BLA) and its application to thin film transistor (TFT). The a-Si film on glass was crystallized by exposure of blue laser for short duration of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~\mu \text{s}$ </tex-math></inline-formula> . The temperature of Si increases up to ~1100 °C and induces fast SPC. A 100 nm poly-Si on glass has full width at half maximum of Raman intensity 5.53 cm−1 and atomic force microscopy (AFM) root mean square surface roughness of 1.18 nm, indicating high quality poly-Si with smooth surface morphology without grain boundary. The coplanar SPC TFT using BLA exhibits the field effect mobility of ~27.0 cm2 / <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}\cdot \text{s}$ </tex-math></inline-formula> , on/off current ratio of >107 and excellent stability.

Biferroelectricity of a homochiral organic molecule in both solid crystal and liquid crystal phases

Ferroelectricity, existing in either solid crystals or liquid crystals, gained widespread attention from science and industry for over a century. However, ferroelectricity has never been observed in both solid and liquid crystal phases of a material simultaneously. Inorganic ferroelectrics that dominate the market do not have liquid crystal phases because of their completely rigid structure caused by intrinsic chemical bonds. We report a ferroelectric homochiral cholesterol derivative, β-sitosteryl 4-iodocinnamate, where both solid and liquid crystal phases can exhibit the behavior of polarization switching as determined by polarization–voltage hysteresis loops and piezoresponse force microscopy measurements. The unique long molecular chain, sterol structure, and homochirality of β-sitosteryl 4-iodocinnamate molecules enable the formation of polar crystal structures with point group 2 in solid crystal phases, and promote the layered and helical structure in the liquid crystal phase with vertical polarization. Our findings demonstrate a compound that can show the biferroelectricity in both solid and liquid crystal phases, which would inspire further exploration of the interplay between solid and liquid crystal ferroelectric phases.

(Invited, Digital Presentation) Nondegenerate Hydrogen-Doped Polycrystalline Indium Oxide (InOx:H) Thin Films for High-Mobility Thin Film Transistors

Transparent metal oxide semiconductors (OSs) have been extensively investigated for use as the active channel layer of thin film transistors (TFTs) for next-generation flat-panel displays, nonvolatile memories, image sensors, and pH sensors, to name a few. Among OSs, the amorphous In–Ga–Zn–O (IGZO) has attracted particular attention for TFT applications owing to its high field effect mobility (μFE) of more than 10 cm2V−1s−1, steep subthreshold swing (S.S.), extremely low off-state current, large-area uniformity, and good bias stress stability. Although the μFE of an IGZO TFT is approximately one order of magnitude higher than that of an amorphous Si TFT, further improvement of the μFE of OS TFTs is required to expand their range of applications as an alternative to polycrystalline Si TFT.Single-crystalline In2O3 has a Hall mobility as high as 160 cm2V−1s−1, which makes amorphous (a-) or polycrystalline (poly-) InOx a potential material for enhancing the μFE of OS TFTs. However, undoped InOx thin films is known as a degenerate semiconductor with high background electron density of over 1020 cm-3, which is attributed to the presence of native defects, such as oxygen vacancies, making them unsuitable for a channel material of OS TFTs. In this presentation, nondegenerate hydrogen-doped polycrystalline InOx (poly-InOx:H) thin films were successfully prepared by low-temperature solid phase crystallization (SPC). A degenerate amorphous InOx:H thin film was deposited by sputtering in Ar, O2, and H2 gases, and an amorphous to polycrystalline phase transition (SPC) of the film was achieved after PDA at more than 175 °C. By PDA at 250 °C in air, a nondegenerate poly-InOx:H film could be obtained with a carrier density as low as 2.4 × 1017 cm−3, which is approximately three orders of magnitude lower than that of the initial a-InOx:H film. The TFTs with a 50 nm thick nondegenerate poly-InOx:H channel could be fully depleted by a gate electric field. A maximum μFE of 125.7 cm2V−1s−1 was exhibited by the TFT with the poly-InOx:H channel. The use of a nondegenerate poly-InOx:H film is a promising approach to boost the μFE of OS TFTs.

(Invited) Hydrogenated Polycrystalline In2O3 (In2O3:H) Thin-Film Transistor with High Mobility Exceeding 100 cm2V−1s−1 Via Solid-Phase Crystallization

Oxide semiconductors have been extensively studied as active channel layers of thin-film transistors (TFTs) for electronic applications. However, the field-effect mobility (μ FE) of oxide TFTs is not sufficiently high to compete with that of low-temperature-processed polycrystalline-Si TFTs (50–100 cm2V−1s−1). Here, we propose a simple process to obtain high-performance TFTs, namely hydrogenated polycrystalline In2O3 (In2O3:H) TFTs grown via the low-temperature solid-phase crystallization (SPC) process. In2O3:H TFTs fabricated at 300 °C exhibit superior switching properties with µ FE = 139.2 cm2V−1s−1. The hydrogen introduced during sputter deposition plays an important role in enlarging the grain size and decreasing the subgap defects in SPC-prepared In2O3:H. The proposed method does not require any additional expensive equipment and/or change in the conventional oxide TFT fabrication process. We believe these SPC-grown In2O3:H TFTs have a great potential for use in future electronic applications.

Poly-Si thickness and temperature dependent oxide disruption induced by penetration of the interfacial oxide in (p) poly-Si/SiOx passivating contacts

Passivating contacts based on polycrystalline silicon on an interfacial oxide (poly-Si/SiO x ) require a fine-tuned in-diffused dopant profile at the surface of the crystalline silicon wafer. In particular, a strong dopant in-diffusion causes excessive recombination. This study contributes to reveal the yet unclear mechanism of this degradation of passivation. Boron in-diffusion from co-sputtered (p) poly-Si layers through the interfacial oxide is investigated for several layer thicknesses and plateau temperatures during the solid phase crystallization. It is shown that for higher temperatures and unexpectedly also for thicker layers the observed recombination current density increases up to a total loss of passivation, accompanied by a physical interfacial oxide disruption, which is not observed for intrinsic reference layers. This behavior is supported by simple numerical calculations. The recombination current densities are transferred into the actual surface recombination velocity which in turn reveals an exponential increase towards higher boron concentrations at the interface between the oxide and the crystalline Si base. It is concluded that rather dopant penetration of the interfacial oxide is responsible for the degradation of passivation than the actual boron concentration at the interface itself as reported before in literature. • Co-sputtered (p) poly-Si/SiO x passivating contacts degrade towards thicker poly-Si and higher annealing temperatures. • The identified degradation mechanism is a physical disruption of the interfacial oxide. • The degradation is rather driven by boron penetration than by the actual boron concentration at the interface. • Modelling of the actual surface recombination velocity reveals an exponential relation to the interface boron concentration.