Effect of carbon on thermal oxidation of silicon and electrical properties of SiO2-Si structures

Growth of thermal oxide on silicon implanted with carbon at low energies is studied and electrical characteristics of the resulting SiO₂-Si structures are evaluated. After excluding the effect of surface damage on the oxide growth kinetics, it was determined that for the carbon implant doses up to 10¹⁴ cm⁻² the effect on oxide growth kinetics is limited. At higher carbon doses significant retardation of oxide growth was observed. A clear correlation between carbon dose and electrical characteristics of SiO₂-Si structures has also been established. In the case of each parameter of concern in this study its degrActation with increased carbon dose above 10¹⁴cm⁻², which corresponds to carbon concentration in silicon of the order of 10¹⁹ cm³, was observed. These effects may come to play during thermal oxidation of silicon wafers subjected prior to oxidation to the reactive ion etching in carbon containing gases such as CF₄, CHF₃, and others.     

Effect of thermal annealing on the luminescence properties of ZnCdSe/ZnSe quantum-well structures

The thermal stability and luminescence properties of ZnCdSe/ZnSe quantum-well structures grown by molecular-beam epitaxy are investigated. A comparative analysis is made of the photoluminescence spectra of the structures before and after annealing. In the sample spectra after annealing (at 500 °C) a decrease in the intensity of the exciton luminescence line by more than two orders of magnitude, accompanied by an increase in the intensity of the deep levels, is observed. As a result of annealing at a lower temperature (about 400 °C), a narrowing of the exciton luminescence, accompanied by a shift of the maximum toward longer wavelengths, was detected. Fiz. Tekh. Poluprovodn. 31, 296–298 (February 1997)     

退火对纳米VO2薄膜结构及电性能的影响

采用直流反应磁控溅射法在K9玻璃和DBr衬底上制备了VO2薄膜.利用扫描电镜(SEM)、X射线衍射(XRD)、傅里叶红外光谱(FT-IR)对薄膜的形貌、晶相和分子结构等进行分析.结果表明,在氧气气氛下退火后,薄膜颗粒变得清晰可见,平均尺寸约25 nm,薄膜由非晶态结构转变为晶态的VO2,且在(011)方向出现明显择优取...     

快速退火温度对Ag/SrTiO_3/p~+-Si器件阻变特性的影响

采用溶胶-凝胶结合快速退火工艺在p~+-Si基片上制备了Sr Ti O_3薄膜,构建了Ag/Sr Ti O_3/p~+-Si结构的阻变器件,研究了退火温度对薄膜微观结构、阻变特性的影响。结果表明:不同退火温度下薄膜均呈结晶态,并且随退火温度升高,薄膜晶粒有增大的趋势,当退火温度为750℃时,薄膜的衍射峰不明显并且有杂峰出现。不同退火温度下Ag/Sr Ti O_3/p~+-Si器件都具有明显的双极性阻变特性,但退火温度为850℃与900℃的器件在扫描电压达到某一值时电流会出现一个极小值;经850℃退火处理的器件具有更高的高低电阻比(103～104)。当退火温度为800℃及更高时,器件在高阻态下的导电机制以肖特基势垒发射机制为主;低阻态的电荷传导机制则遵循空间电荷限制电流机制(SCLC)。器件在200次可逆循环测试下,退火温度为850℃时表现出较好的抗疲劳特性。     

Structural and optoelectronic properties of nanostructured TiO2 thin films with annealing

About 480 nm thick titanium oxide (TiO₂) thin films have been deposited by electron beam evaporation followed by annealing in air at 300–600 °C with a step of 100 °C for a period of 2 h. Optical, electrical and structural properties are studied as a function of annealing temperature. All the films are crystalline (having tetragonal anatase structure) with small amount of amorphous phase. Crystallinity of the films improves with annealing at elevated temperatures. XRD and FESEM results suggest that the films are composed of nanoparticles of 25–35 nm. Raman analysis and optical measurements suggest quantum confinement effects since Raman peaks of the as-deposited films are blue-shifted as compared to those for bulk TiO₂ Optical band gap energy of the as-deposited TiO₂ film is 3.24 eV, which decreases to about 3.09 eV after annealing at 600 °C. Refractive index of the as-deposited TiO₂ film is 2.26, which increases to about 2.32 after annealing at 600 °C. However the films annealed at 500 °C present peculiar behavior as their band gap increases to the highest value of 3.27 eV whereas refractive index, RMS roughness and dc-resistance illustrate a drop as compared to all other films. Illumination to sunlight decreases the dc-resistance of the as-deposited and annealed films as compared to dark measurements possibly due to charge carrier enhancement by photon absorption.     

Effect of oxygen plasma on the properties of tantalum oxide films

The effect of oxygen plasma on the leakage current, permittivity, and the dielectric loss tangent of Ta₂O₅ thin layers (300–400 nm) is studied. It is suggested to treat tantalum oxide films in oxygen plasma to control their electrical and dielectric characteristics.     

Effect of thermal annealing on structural and optical properties of titanyl phthalocyanine thin films

Thin films of titanyl phthalocyanine (TiOPc) have been deposited on both fused quartz and glass substrates by the thermal evaporation technique. The structural and optical properties of the as-deposited and annealed films have been reported. The structural features of the as-deposited and annealed films have been studied by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Fourier-transform infrared (FT-IR) technique. The optical constants (refractive index, n, and absorption index, k) of the films have been presented for the first time in the wavelength range 200–2500 nm by using spectrophotometric measurements at nearly normal incidence. The band gaps of the as-deposited film at 1.48 eV and 2.5 eV corresponding to Q-band and B or Soret band were red-shifted to 1.15 eV and 2.19 eV, respectively, when the film annealed at 433 K.     

Effect of thermal annealing on optical and photoelectric properties of microcrystalline hydrogenated silicon films

The effect of thermal annealing in the temperature range T _a=300–600°C of films of microcrystal-line hydrogenated silicon (μc-Si:H) lightly doped with boron on the spectral dependences of the absorption coefficient (α) at photon energies hν=0.8–2.0 eV, dark conductivity (σ_d), and photoconductivity (Δσ_ph) was studied at room temperature. With increasing annealing temperature, a nonmonotonic variation of α (at hν<1.2 eV), σ_d, and Δσ_ph was observed. The data obtained are attributed to a change in the concentration of electrically active impurities and formation of defects, caused by hydrogen effusion and bond restructuring at high annealing temperatures.     

Rapid thermal annealing effects on the optical properties of GaAs0.9−xNxSb0.1 structures grown by MBE

In this work, we report on the effect of rapid thermal annealing on GaAs_0.9−xN_xSb_0.1 structures, grown by molecular beam epitaxy, using room temperature spectroscopic ellipsometry (SE). A comparative study was carried out on two sets of GaAs_0.9−xN_xSb_0.1 as-grown and annealed samples with small nitrogen content (x up to 0.013). The results obtained from the ellipsometric data analysis allow us to extract the annealing effect on the pseudodielectric functions and the transition energies as function of nitrogen content. A blue shift of the E₀ transition was recorded, while the higher E₁, E₁+Δ₁ and E₀′ transition energies are not affected with post-growth annealing. The nitrogen level E_N, obtained from the band anticrossing model fit to the E₀ transition energies values, is found to increase upon annealing from 1.60 (±0.06) eV to 1.80 (±0.08) eV. The resulting calculated electron effective mass is found to decrease with annealing the GaAs_0.9−xN_xSb_0.1 structures.     

Transformation of a SiC/por-SiC/TiO2 structure during rapid thermal annealing

The surface morphology and the Raman and photoluminescence spectra of a SiC/por-SiC/TiO₂ structure before and after rapid thermal annealing are studied. It is shown that rapid thermal annealing brings about the appearance of new bands in the Raman spectrum; these bands are characteristic of carbon compounds. An analysis of the spectra of photoluminescence excited by radiation with an energy lower than that of the band-gap energy in 6H-SiC has shown that the appearance of photoluminescence in porous silicon carbide is related to impurity states, which are formed at the surface due to products of chemical reactions in the course of etching.     

Effect of rapid thermal annealing on properties of thermally evaporated nanostructured CdTe thin film treated with CdCl2

The effects of rapid thermal annealing on properties of crystalline nanostructured CdTe films treated with CdCl₂ and prepared by vacuum evaporation are described. X-ray diffraction confirmed the crystalline nature of post-treated films with high preferential orientation around 23.7°, corresponding to a (1 1 1) diffracted plane of cubic phase. Optical band gap of CdTe films increased from 1.4 eV to 1.48 eV after annealing at 500 °C for 90 s. Atomic force microscopy of annealed films revealed an increase in root mean square roughness and grain size with increased annealing time. Electrical measurements of as-grown and annealed films are consistent with p-type; film resistivity has decreased significantly with increased annealing time.     

Electrical,optical, and photoluminescence properties of ZnO films subjected to thermal annealing and treatment in hydrogen plasma

The photoluminescence and optical absorption spectra and electrical properties of ZnO films grown by the metal–organic chemical vapor deposition and hydrothermal techniques, subjected to heat treatments and plasma treatment in a hydrogen atmosphere, are studied. It is shown that the adsorption of oxygen at grain boundaries upon annealing in an oxidizing atmosphere determines the electrical properties of the films. Vacuum annealing improves the electrical properties of the samples after degradation induced by annealing in air. Treatment in hydrogen plasma passivates surface states at the grain boundaries. The intrinsic photoluminescence intensity after plasma treatment is higher in the case of increased amounts of oxygen adsorbed at grain surfaces upon annealing in air. Surface states involving oxygen and hydrogen atoms are responsible for the high-intensity intrinsic photoluminescence band.     

Effect of rapid thermal annealing of sputtered aluminium nitride film in an oxygen ambient

Aluminium nitride (AlN) thin films were deposited by radio frequency (RF) magnetron sputtering on p-type silicon (Si) substrate of (1 0 0) orientation using only argon (Ar) gas at substrate temperature of 300 °C. In order to achieve improved electrical properties, we performed post-deposition rapid thermal annealing (RTA). Sputtered AlN films were annealed in an oxygen ambient at temperatures of 600, 700, and 800 °C using RTA for 30 min. The orientation of the AlN crystal in the film was investigated using X-ray diffraction (XRD). The characteristic spectra by functional group were analyzed by Fourier transformation infrared (FTIR) spectroscopy. The electrical properties of the AlN thin films were studied through capacitance–voltage (C–V) characteristics in metal–insulator–semiconductor (MIS) device using the films as insulating layers. The flatband voltages (V_FB) in C–V curves were found to depend on crystal orientations. Negative V_FB was found in the case when AlN (1 0 0) peak was found. Also, when AlN (1 0 3) peak was observed upon increasing the annealing temperature, the value of V_FB was positive and after annealing at 700 °C, AlN (1 0 3) peak intensity was found to be maximum and V_FB was as high as+6.5 V.     

Device and material properties of pseudomorphic HEMT structuressubjected to rapid thermal annealing

The device-related effects of rapid thermal annealing (RTA) on the electrical and optical properties of planar-doped AlGaAs/InGaAs/GaAs high-electron-mobility transistor structures grown by molecular beam epitaxy were investigated. Specifically, electrical and optical characterization techniques such as capacitance versus voltage, current versus voltage, Hall effect, and photoluminescence have been applied to study the effects that typical III-V compound semiconductor rapid thermal processes (RTPs) have on the properties of pseudomorphic AlGaAs/InGaAs/GaAs structures for two different values of In mole fraction content. The effect and stability of the indium mole fraction on both heterostructure and device integrity with respect to RTA schedule has been investigated in detail     

Effect of fast annealing on the electrical properties of SiO2/Si structures with thin layers of anodic silicon oxide

Effects of fast annealing on the properties of SiO₂/Si structures with thin, ～10 nm, layers of anodic silicon oxide formed on single-crystal Si substrates are studied in relation to the semiconducting properties of the silicon support and to the duration, temperature, and environment of thermal treatment. The optimal duration of high-temperature annealing of structures in an inert atmosphere for their application in the technology of nanosize MOS integrated circuits is determined.     

快速退火对Pt/BST/Pt电容器结构和性能的影响

采用脉冲激光沉积(PLD)法在Pt/Ti/SiO2/Si(001)基片上制备了Ba0.6Sr0.4TiO3(BST)薄膜,对Pt/BST/Pt电容器在空气中进行400℃快速退火(RTA)处理,研究了快速退火对Pt/BST/Pt电容器的结构和性能的影响。结果表明:快速退火虽然对BST薄膜的结晶质量影响较小,但却极大改善了Pt/BST/Pt电容器的电学性能。当测试频率为100kHz、直流偏压为0V时,介电损耗从快速退火前的0.07减小到0.03,介电常数和调谐率略有增加。快速退火后负向漏电流过大现象得到了明显抑制,正负向漏电流趋于对称,在300×103V/cm电场强度下,漏电流密度为4.83×10–5A/cm2。     

Effect of thermal annealing on the sensitivity of Si-based MOS diodes to reducing gases

We study the effect of thermal annealing in the range of 200–610°C on the sensitivity and time dependences of the response of the Pd-SiO₂-n-Si diodes to hydrogen and ammonia. The postannealing surface of a Pd electrode was examined using atomic force microscopy. The high-frequency C-V characteristics were measured in air and gas mixtures H₂-air and NH₃-air. It is shown that, after annealing at 200°C for 10 min, the response of diode capacitance to hydrogen is higher than that to ammonia. After annealing at 300°C and higher, the sensitivity of MOS diodes to hydrogen nearly vanishes. The response to ammonia still remains high, although it gradually weakens as the annealing temperature is increased. A decrease in sensitivity of the Pd-SiO₂-n-Si diodes to ammonia with increasing temperature is attributed to worsening of the electrical characteristics of the Pd electrode.     

Effect of thermal annealing on the electrical properties of P3HT:PC70BM nanocomposites

We studied the electrical properties of organic photovoltaic (OPV) devices based on poly (3-hexylthiophene) and fullerene derivative [6, 6]-Phenyl-C₇₀-butyric acid methyl ester nanocomposite (P3HT:PC₇₀BM) as a function of the annealing temperature. Thermal annealing enables crystallization of the polymer and diffusion of the PC₇₀BM molecules. Diode parameters, such as the barrier height ϕ_b and the ideality factor n were calculated. They were found to be depend strongly on the annealing temperature. This dependence is attributed to surface states, inhomogeneity in the material and series resistance. Best OPV devices had a short circuit current density of 3.35 mA/cm², an open circuit voltage of 0.68 V, a fill factor of 0.45, and a power conversion efficiency of 2.2%, by applying a thermal annealing temperature of 150 °C for 10 min.     

Effects of thermal annealing on the photophysical properties of bisfluorene-cored dendrimer films

Annealing is widely used in the processing of organic semiconductors, and can modify their film morphology and photophysical properties. A study of the effect of annealing on films made from a blue emitting bisfluorene-cored dendrimer is reported. Annealing causes a 15 nm blue-shift in the photoluminescence (PL) spectrum and an 11 nm blue-shift in the amplified spontaneous emission (ASE) spectrum. It causes the PL efficiency to decrease only slightly from 0.92 to 0.83. The radiative decay rate of 1.3 × 10⁹ s^?1, the ASE threshold of 1.5 × 10¹⁸ cm^?3 and the singlet–singlet exciton annihilation rate of 5.5 × 10^?10 cm³ s^?1 are unaffected by annealing. The results indicate a scope for colour adjustment of dendrimer light-emitting diodes and lasers without affecting their efficiencies. Investigation by spectroscopic ellipsometry shows that on annealing, the films become anisotropic, with larger values of the refractive index and extinction coefficient observed for light polarised in the plane of the film than the corresponding out-of-plane values in the absorption region of the bisfluorene core. This anisotropy indicates a preferential in-plane orientation of bisfluorene cores upon annealing.     

Effect of thermal annealing on physical properties of vacuum evaporated In2S3 buffer layer for eco-friendly photovoltaic applications

The present communication reports the effect of thermal annealing on the physical properties of In₂S₃ thin films for eco-friendly buffer layer photovoltaic applications. The thin films of thickness 150 nm were deposited on glass and indium tin oxide (ITO) coated glass substrates employing thermal vacuum evaporation technique followed by post-deposition thermal annealing in air atmosphere within a low temperature range 150–450 °C. These as-deposited and annealed films were subjected to the X-ray diffraction (XRD), UV–vis spectrophotometer, current–voltage tests and scanning electron microscopy (SEM) for structural, optical, electrical and surface morphological analysis respectively. The compositional analysis of as-deposited film is also carried out using energy dispersive spectroscopy (EDS). The XRD patterns reveal that the as-deposited and annealed films (≤300 °C) have amorphous nature while films annealed at 450 °C show tetragonal phase of β-In₂S₃ with preferred orientation (109) and polycrystalline in nature. The crystallographic parameters like lattice constant, inter-planner spacing, grain size, internal strain, dislocation density and number of crystallites per unit area are calculated for thermally annealed (450 °C) thin films. The optical band gap was found in the range 2.84–3.04 eV and observed to increase with annealing temperature. The current–voltage characteristics show that the as-deposited and annealed films exhibit linear ohmic behavior. The SEM studies show that the as-deposited and annealed films are uniform, homogeneous and free from crystal defects and voids. The grains in the thin films are similar in size and densely packed and observed to increase with thermal annealing. The experimental results reveal that the thermal annealing play significant role in the structural, optical, electrical and morphological properties of deposited In₂S₃ thin films and may be used as cadmium-free eco-friendly buffer layer for thin films solar cells applications.