Influence Of Post-deposition Annealing Research Articles

Influence of post-deposition annealing on the novel alloyed SnSxO1-x semiconductor in p-type thin-film transistors

SnO is an oxide semiconductor that has the potential to be used in the development of thin-film transistors (TFTs) with a p-type channel. SnO on the other hand is a metastable phase, and the oxidation of the SnO films makes high-performance TFTs with good mobility and high on/off current ratios challenging. In this study, based on the SnO–SnO2 phase transformation mechanism, a novel alloyed semiconductor SnSxO1-x was reported to prevent the conversion of SnO to SnO2. Pulsed laser deposition was used to grow SnO and SnSxO1-x thin films on Si/SiO2 substrates, which were then exposed to rapid annealing procedures. From Raman spectroscopic analysis, SnSxO1-x exhibited better antioxidant performance than pure SnO at the same post-deposition annealing process. The developed SnSxO1-x TFTs exhibited better stability and an improved on/off ratio than SnO TFTs after high-temperature annealing. Additionally, we fabricated bilayer SnSxO1-x/SnO thin-film transistors with typical p-channel conduction and a 10−11 A off-state current.

Influence of post-deposition annealing on the transport properties of sputtered Bi2Se3 thin films

The fabrication of chalcogenide-based topological insulator (TI) thin films with low defects and vacancies is an important research problem. In the past decade, Bi2Se3 is one of the most investigated TI materials. The physical properties of Bi2Se3 are dictated by selenium vacancies irrespective of the growth method. Controlling the number of vacancies is very challenging, but it can be influenced by substrate and growth temperature. In this work, we demonstrate that post-deposition annealing temperature is also effective in controlling the carrier concentration of Bi2Se3 thin films. Ultra-thin Bi2Se3 films were fabricated on quartz substrates using magnetron sputtering at room temperature, and their resistivity, bulk carrier concentration, and bulk mobility are measured as a function of the post-deposition annealing temperature under vacuum conditions ranging from 180–350 °C. We find that the carrier concentration can vary by an order of magnitude, and we obtained values as low as ~1 × 1019 cm−3 between 200-250 °C which compares very well with some of the best literature reports on films made by molecular beam epitaxy. Room temperature bulk mobility values in excess of 100 cm2/Vs were recorded for the optimally annealed samples. Energy dispersive x-ray spectroscopy measurements showed that selenium-rich Bi2Se3 films have the highest carrier concentration values. X-ray diffraction measurements showed that the best crystallographic properties are obtained for stoichiometric Bi2Se3. Our results indicate that higher mobility values may be possible if better crystal structure and lower resistivity are obtained in selenium-rich films.

Influence of post-deposition annealing on electrical and optical properties of (Ta2O5)1-x - (TiO2)x thin films, x ≤ 0.08

Tantalum (Ta) and titanium (Ti) metal targets were direct current (DC) magnetron sputtered in the oxygen environment by varying its relative areas to deposit (Ta2O5)1-x- (TiO2)x (TTOx) thin films, with x = 0, 0.03, 0.06, and 0.08, onto the boron-doped p-silicon (1 0 0) and optically polished quartz substrates, at room temperature; and were annealed at 500, 600, 700, and 800 °C, for 1.5 h. The thin films annealed at and above 600 °C show the Ta2O5 structure. The leakage current density and capacitance-voltage (C–V) characteristics were measured for TTOx, x ≤ 0.08, assisted Ag/TTOx/p-Si metal– oxide– semiconductor (MOS) structures. The leakage current density was found minimum, for the films annealed at 800 °C, for all the prepared TTOx films, x ≤ 0.08. The minimum leakage current density 1.6 × 10−8 A/cm2, at 3.5 × 105 V/cm electric field, was observed for x = 0.03, annealed at 800 °C, among the prepared compositions. The prepared TTO0.03 films, annealed at 700 °C show maximum dielectric constant 39, at 1 MHz. The optical parameters, viz., refractive index (n), extinction coefficient (k), and optical band gap (Eg) of the films, with x = 0.03, prepared on quartz substrates, were determined from their optical transmittance plots. The values of n and k of the crystalline films were observed increasing from 2.123 to 2.143, and 0.099 to 0.130, respectively, at 550 nm wavelength; and Eg decreasing from 3.95 to 3.89 eV with the increasing annealing temperature, from 600 to 800 °C. Ohmic emission, in the lower electric field; Schottky and space-charge- limited current conduction mechanisms, in the intermediate to higher electric fields, were generally envisaged from the current-voltage characteristics in the prepared Ag/TTO0.03/p-Si structures.

The Microstructure, Mechanical and Friction-Wear Properties of (TiBx/TiSiyCz)x3 Multilayer Deposited by PLD on Steel

The microstructure, mechanical properties, and friction-wear performance of (TiBx/TiSiyCz)x3 multilayer coatings deposited on the M2 steel by the pulsed laser deposition are investigated in detail in as-deposited state and after annealing at 500 °C for 5 min in air. Scanning and transmission electron microscopies are used to reveal microstructural changes caused by annealing. The influence of post-deposition annealing on hardness and Young modulus is studied in nanoindentation test. A scratch-test is applied to reveal changes in adhesion and the coefficient of friction (CoF) of coated samples with diamond before and after annealing. Friction-wear properties are also analyzed in dry sliding with Al2O3 and 100Cr6 steel in ball-on-disc tests. Our analysis shows that the post-deposition annealing leads to partial devitrification of the TiBx layers, where nanocrystalline TiB2 phase is identified, while the TiSiyCz layers retain amorphous. Annealing significantly increases mechanical properties of coated samples and adhesion of the (TiBx/TiSiyCz)x3 multilayer to steel substrates. Friction-wear properties of coated samples are also notably improved. The values of CoF for coated samples tested with diamond (in the scratch-test), alumina, and 100Cr6 steel (ball-on-disc tests) are in the range of 0.05–0.23, while for M2 steel the CoF values are 0.8, 0.45, and 0.8, respectively.

Influence of post-deposition annealing on the photoelectrochemical performance of CuBi2O4 thin films

Complex metal oxide semiconductors are promising candidates to be used as photoelectrodes in solar water splitting devices. One particular example is copper bismuth oxide (CuBi2O4), which is a p-type semiconductor with an ideal bandgap of 1.6–1.8 eV and suitable band positions. However, the performance has been reported to be limited by photocorrosion and the mismatch between its optical absorption and charge carrier transport properties. It has been shown that the former can be overcome by the deposition of protection layers, while the latter can be addressed by the modification of the bulk properties of the material. Here, we deposited thin films of CuBi2O4 using pulsed laser deposition (PLD). This results in high quality films, as evident from the internal quantum efficiency, which is comparable to the best-performing CuBi2O4 photoelectrodes. We investigate the bulk modification of the films by exploring post-deposition annealing treatment at various temperatures and oxygen partial pressures. These post-deposition annealing parameters influence the morphology of the films through the formation of aggregated particles/islands with higher crystallinity. The anneal treatment reduces bulk recombination in the film and increases the AM1.5 photocurrent by a factor of more than three. The influence of the high temperature post-deposition annealing treatment on other properties of CuBi2O4 (absorption, formation, and suppression of defects) is also discussed. This study underlines the importance of high temperature post-deposition annealing treatment in optimizing the performance of complex metal oxide photoelectrodes.

Influence of post-deposition annealing on the chemical states of crystalline tantalum pentoxide films

We investigate the effect of post-deposition annealing (for temperatures from 848 K to 1273 K) on the chemical properties of crystalline Ta$_2$O$_5$ films grown on Si(100) substrates by radio frequency magnetron sputtering. The atomic arrangement, as determined by X-ray diffraction, is predominately hexagonal ($\delta$-Ta$_2$O$_5$) for the films exposed to heat treatments at 948 K and 1048 K; orthorhombic ($\beta$-Ta$_2$O$_5$) for samples annealed at 1148 K and 1273 K; and amorphous for samples annealed at temperatures below 948 K. X-ray photoelectron spectroscopy for Ta $4f$ and O $1s$ core-levels were performed to evaluate the chemical properties of all films as a function of annealing temperature. Upon analysis, it is observed the Ta $4f$ spectrum characteristic of Ta in Ta$^{5+}$ and the formation of Ta-oxide phases with oxidation states Ta$^{1+}$, Ta$^{2+}$, Ta$^{3+}$, and Ta$^{4+}$. The study reveals that the increase in annealing temperature increases the percentage of the state Ta$^{5+}$ and the reduction of the others indicating that higher temperatures are more desirable to produce Ta$_2$O$_5$, however, there seems to be an optimal annealing temperature that maximizes the O\% to Ta\% ratio. We found that at 1273 K the ratio slightly reduces suggesting oxygen depletion.

Influence of post-deposition annealing on structural, morphological and optical properties of copper (II) acetylacetonate thin films

In this study, the effect of thermal annealing under vacuum conditions on structural, morphological and optical properties of thermally evaporated copper (II) acetylacetonate, cu(acac)2, thin films were investigated. The copper (II) acetylacetonate thin films were deposited using thermal evaporation technique at vacuum pressure ~1 × 10−5 mbar. The deposited films were thermally annealed at 323, 373, 423, and 473 K for 2 h in vacuum. The thermogravimetric analysis of cu(acac)2 powder indicated a thermal stability of cu(acac)2 up to 423 K. The effects of thermal annealing on the structural properties of cu(acac)2 were evaluated employing X-ray diffraction method and the analysis showed a polycrystalline nature of the as-deposited and annealed films with a preferred orientation in [1¯01] direction. Fourier transformation infrared (FTIR) technique was used to negate the decomposition of copper (II) acetylacetonate during preparation or/and annealing up to 423 K. The surface morphology of the prepared films was characterized by means of field emission scanning electron microscopy (FESEM). A significant enhancement of the morphological properties of cu(acac)2 thin films was obtained till the annealing temperature reaches 423 K. The variation of optical constants that estimated from spectrophotometric measurements of the prepared thin films was investigated as a function of annealing temperature. The annealing process presented significantly impacted the nonlinear optical properties such as third-order optical susceptibility χ(3) and nonlinear refractive index n2 of cu(acac)2 thin films.

Influence of post-deposition annealing on structural, optical and transport properties of nanocomposite ZnO-Ag thin films

Thin films of ZnO and ZnO-Ag were grown by rf sputter deposition and post-annealed in air in the 300–600 °C temperature range. Annealing caused variation in strain in ZnO films and significant improvement of ZnO in ZnO-Ag films. The partial oxidation of Ag into AgxO upon annealing of ZnO-Ag films in air resulted in increase of transmittance, absorption due to AgxO phase, weakening of surface plasmon resonance absorption due to Ag nanocrystals and an increase in fluorescence. Surface studies indicate temperature induced particle transport cause agglomeration of nanocrystals in ZnO-Ag films during post-annealing. Annealed ZnO films showed a decrease in dark current and a sixteenfold increase in photocurrent at 3 V applied bias under white light illumination due to the formation of charged acceptors / oxygen vacancy centres, which was comparable to the white light photosensitivity of as-deposited ZnO-Ag film. For low applied bias voltages, Metal-Semiconductor-Metal photoconductive detectors made with annealed ZnO-Ag films showed potential for application as efficient deep ultraviolet (DUV) photodetectors with negligible sensitivity to white light and high sensitivity to DUV light.

Influence of processing conditions on the optical properties of chemically deposited zinc sulphide (ZnS) thin film

In this paper, we present the influence of post deposition annealing and varying concentration on the optical properties of ZnS thin films fabricated by chemical bath deposition (CBD) at 65 °C from chemical baths comprising NH3/SC(NH2)2/ZnSO4 solutions at pH of about 10. The film samples were annealed at temperatures ranging from 373 K–473 K and the concentration of the film samples vary from 0.1 M–0.7 M. Post deposition annealing and concentration played an important role on the optical parameters investigated which includes absorbance, transmittance, reflectance, absorption coefficient, band gap, refractive index and extinction coefficient. The optical parameters were found to vary with post deposition annealing in one direction and concentration of Zn2+ in the reverse direction. For instance, post deposition annealing increases the band gap from 3.65 eV for as-deposited to 3.70 eV, 3.75 eV and 3.85 eV for annealed at 373 K, 423 K and 473 K respectively whereas concentration of Zn2+ decreases the band gap from 3.95 eV at 0.1 M to 3.90 eV, 3.85 eV and 3.80 eV at 0.3 M, 0.5 M and 0.7 M respectively. The fundamental absorption edge of ZnS thin films shifted toward the highest photon energies (blue shift) after annealing and shifted toward the lowest photon energies (red shift) with increasing Zn ions concentration. A linear relation between band gap energy and Urbach energy was found. After annealing, the Urbach energy increases form 3.10 eV to 3.50 eV and decreases from 3.40 eV to 3.10 eV at varying Zn2+ concentration. The property of wide band gap makes ZnS suitable for buffer layer of film solar cells, permitting more light especially the short wavelength light into absorber layer.

Investigation of Gate-Stacked In-Ga-Zn-O TFTs with Ga-Zn-O Source/Drain Electrodes by Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition.

Atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) was employed for the fabrication of indium gallium zinc oxide thin-film transistors (IGZO TFTs) with high transparent gallium zinc oxide (GZO) source/drain electrodes. The influence of post-deposition annealing (PDA) temperature on GZO source/drain and device performance was studied. Device with a 300 °C annealing demonstrated excellent electrical characteristics with on/off current ratio of 2.13 × 108, saturation mobility of 10 cm2/V-s, and low subthreshold swing of 0.2 V/dec. The gate stacked LaAlO3/ZrO2 of AP-IGZO TFTs with highly transparent and conductive AP-GZO source/drain electrode show excellent gate control ability at a low operating voltage.

Influence of post-deposition annealing on the structural and optical properties of γ-MnS thin film

γ-MnS thin film was deposited at 40 °C temperature on glass substrate by Chemical Bath Deposition (CBD) method that has superior advantageous in terms of fast and cheap production. MnS thin film was annealed in nitrogen atmosphere at temperatures 100, 200, 300, 400, 500 °C for an hour. The effect of annealing temperature on structural and optical properties have been investigated. X-ray diffraction (XRD) analysis revealed that gamma-MnS thin film had the phase change and oxidized at 400, 500 °C annealing temperature. The grain size of the annealed film was calculated between 241 and 280 Å as a function of annealing temperature. It was observed that optical transmission values decreased at wavelength of 400–700 nm (visible region) after annealing at temperatures 400 and 500 °C. Increasing annealing temperature induces reduction in energy band gap values from 3.89 eV down to 3.46 eV. Refractive index (n) values were calculated by envelope method. Refractive index values at visible region increased from 2.03 to 2.54 with increasing annealing temperature.

Influence of post-deposition annealing and the ITO underlayer on the properties of hybrid TiO2/ITO nanocomposite for enhanced hydrogen sensing at room temperature

We report the effect of heat treatment on room temperature hydrogen sensing performance of TiO2 films prepared on ITO coated glass substrate by a novel spray deposition. Our outcomes show that the better sensitivity of the sensor strongly depends on the surface morphology of TiO2 film and the ITO under layer. All the films exhibit polycrystalline nature of tetragonal crystal structure. The average particle size of the preferential (101) peak of TiO2 was found to be 7–13nm. Heat treatment played a crucial role in the improvement of the crystal quality and energy band gap of the bilayered TiO2/ITO films. The UV spectra show shift in the absorption edge towards lower wavelength with increase in annealing temperature. XRD and Raman data suggest the phase-pure anatase creation. The sensor response was tested for hydrogen concentrations of 200–800ppm at room temperature. Predominantly, the TiO2/ITO nanocomposite annealed at 300°C exhibited more promising sensor behavior to even low concentration of 200ppm hydrogen at room temperature. The highly ordered porous nanospherical oxide structures achieved on ITO nanoclusters revealed a high sensor resistance of 85MΩ, with fast recovery of 4s. The hybrid sensor also exhibited good selectivity to H2 gas compared with other gases ethanol and acetone studied under the same operating condition.

The influence of post-deposition annealing on the structure, morphology and luminescence properties of pulsed laser deposited La0.5Gd1.5SiO5 doped Dy3+ thin films

The influence of post-deposition annealing on the structure, particle morphology and photoluminescence properties of dysprosium (Dy3+) doped La0.5Gd1.5SiO5 thin films grown on Si(111) substrates at different substrate temperatures using pulsed laser deposition (PLD) technique were studied. The X-ray diffractometer results showed an improved crystallinity after post-annealing. The topography and morphology of the post-annealed films were studied using atomic force microscopy and field emission scanning electron microscopy respectively. The elemental composition in the surface region of the films were analyzed using energy dispersive X-ray spectroscopy. The photoluminescence studies showed an improved luminescent after post-annealing. The cathodoluminescence properties of the films are also reported. The CIE colour coordinates calculated from the photoluminescence and cathodoluminescence data suggest that the films can have potential application in white light emitting diode (LED) and field emission display (FED) applications.

Influence of Post-Deposition Annealing on Structure and Optical Characteristics of Niobium Oxide Thin Films

In this work, niobium oxide thin films were deposited on silicon wafer (100) and glass slide substrate by reactive magnetron sputtering. The niobium oxide films were further annealed and effect of post annealing on the crystallinity, microstructure and optical properties was studies. In order to identify the crystalline structure and microstructure, X-ray diffraction (XRD) and scanning electron microscope (SEM) measurement carried out. The optical property was determined by UV-Vis spectrophotometer. It has been observed that with increase in annealing temperature films become microcrystalline films. In particularly, the optical property of niobium oxide thin film also improves with annealing temperature.

Nb-doped TiO2 thin films for photovoltaic applications

Abstract Polycrystalline titania and Nb:TiO 2 thin films were deposited by RF magnetron sputtering. The influence of post-deposition annealing in vacuum and hydrogen atmosphere on the structure, morphology, oxidation states and optical properties was studied by X-ray diffraction, atomic force microscopy, XPS and UV–VIS spectroscopy. The heat treatment of titanium dioxide thin films in vacuum and H 2 atmosphere induces structural and morphological changes. The band gap narrowing was observed for the transparent as-deposited Nb:TiO 2 films, while annealing at 420 °C in H 2 atmosphere resulted in an enhancement of the electrical conductivity. Further on, TiO 2 / p -CdTe photovoltaic devices with efficiency of 1.8% were fabricated and their characteristic ‘enhancement’ is discussed.

Influence of post-deposition annealing under magnetic field on the structure of phthalocyanine thin films

A comparative analysis of the influence of post deposition annealing process without and under applied magnetic field of 1 T, on structure and morphology of VOPcF16 films, has been carried out. The phase transition of VOPcF16 film upon its annealing under applied magnetic film was studied by the methods of UV–Visible and Raman spectroscopies as well as atomic force microscopy. It was shown that the temperature of the phase transition of VOPcF16 decreases from 160 to 100 °C, when magnetic field is applied during post deposition annealing. The formation of VOPcF16 films with elongated crystallites oriented preferably in one direction was observed after their annealing in magnetic field. The current–voltage characteristic measurements demonstrated an increase in the lateral conductivity for the films annealed under applied magnetic field in comparison with the films annealed without magnetic field.

Effect of post-sulfurization on the structural and optical properties of Cu 2 ZnSnS 4 thin films deposited by vacuum evaporation method

Abstract The influence of post deposition annealing in sulfur atmosphere on the structural and optical properties of Cu2ZnSnS4 (CZTS) thin films was investigated. The samples were deposited by thermal evaporation under vacuum method at different glass substrate temperatures ranging from 60 °C to 210 °C. After the deposition, all CZTS thin films were annealed in a furnace in sulfur atmosphere at a temperature of 400 °C during 2 h so as to optimize the kesterite CZTS phase. Structural characterization was carried out using X-ray diffraction and Raman Scattering whereas optical characterization was performed by recording transmittance and reflectance of the samples in the spectral range of 300 nm–2400 nm. The X-ray diffraction spectra indicated that polycrystalline CZTS films were obtained after annealing and the samples exhibit (112) preferred diffraction plane. Hence, crystallinity was enhanced with substrate temperature as well as with post deposition annealing due to the diffusion of sulfur in the film during the annealing process. Optical study reveals that after annealing, the absorption coefficient is found to be higher than 105 cm− 1 whereas the direct band gap energy varies in the range of 1.4 eV–1.6 eV.

Influence of post-deposition annealing on the electrical properties of zinc oxide thin films

The influence of the post-deposition annealing (PDA) temperature and the use of different ambient gases on the structural and electrical properties of zinc oxide thin films grown by atomic layer deposition were investigated. The PDA did not change the optical properties of the films, but a slight improvement in the crystallinity was observed. The PDA strongly affected the electrical properties of the ZnO films. High-temperature annealing in air ambient led to the increase in resistivity, and high-temperature annealing in reducing N2/H2 ambient delayed such an increase. The increase in resistivity was correlated with the generation of deep-level trap states, as manifested by the increase of the red emission band centered at ~630nm (~1.97eV) from photoluminescence.

Influence of post-deposition annealing on interfacial properties between GaN and ZrO2 grown by atomic layer deposition

Influence of post-deposition annealing on interfacial properties related to the formation/annihilation of interfacial GaOx layer of ZrO2 grown by atomic layer deposition (ALD) on GaN is studied. ZrO2 films were annealed in N2 atmospheres in temperature range of 300 °C to 700 °C and analyzed by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. It has been found that Ga-O bond to Ga-N bond area ratio decreases in the samples annealed at temperatures lower than 500 °C, which could be attributed to the thinning of GaOx layer associated with low surface defect states due to “clean up” effect of ALD-ZrO2 on GaN. However, further increase in annealing temperature results in deterioration of interface quality, which is evidenced by increase in Ga-O bond to Ga-N bond area ratio and the reduction of Ga-N binding energy.

Low-temperature post-deposition annealing investigation for 3D charge trap flash memory by Kelvin probe force microscopy

The influence of post-deposition annealing (PDA) temperature condition on charge distribution behavior of HfO2 thin films was systematically investigated by various-temperature Kelvin probe force microscopy technology. Contact potential difference profiles demonstrated that charge storage capability shrinks with decreasing annealing temperature from 1,000 to 500 °C and lower. Compared to 1,000 °C PDA, it was found that 500 °C PDA causes deeper effective trap energy level, suppresses lateral charge spreading, and improves the retention characteristics. It is concluded that low-temperature PDA can be adopted in 3D HfO2-based charge trap flash memory to improve the thermal treatment compatibility of the bottom peripheral logic and upper memory arrays.