Herein, SnSe2 QDs have successfully been prepared by liquid-phase ultrasonic exfoliation of the group IV metal-sulfide compounds. The morphology and structure of the SnSe2 QDs were characterized by transmission electron microscopy (TEM) and high-resolution transmission microscopy (HR-TEM), and the composition of the materials was analyzed by X-ray diffraction (XRD) and Raman spectroscopy (Raman). The absorbance of the samples with different wavelengths was analyzed by UV-Vis spectrophotometer, and the fluorescence intensity at different excitation wavelengths was studied by fluorescence spectrometer (PL), and the effect of different centrifugal speeds on the particle size of QDs and the spectral red-shift caused by the size effect was investigated. The average lateral sizes of SnSe2 QDs samples obtained at centrifugal speeds of 3500, 1500 and 500 rpm were 1.86 nm, 2.73 nm, and 3.3 nm, respectively. The SnSe2 QDs exhibited significant absorption in the infrared band and red-shift with increasing QDs size, The results demonstrated the potential use of this new material in infrared detection.

量子点因具有优异的光电特性，近年来备受关注。但量子点的规模化应用因受到其加工工艺及稳定性等因素限制而尚待开发。量子点-聚合物纳米复合材料的出现有效弥补了这一问题，将量子点分散到有机聚合物中形成纳米复合材料，集合量子点与聚合物的各自优势于一体，是解决量子点当前应用问题的一种有效方法，具有显著的发展潜力。文中介绍了量子点的主要制备技术，并在此基础上对量子点-聚合物复合材料的制备方法及其在激光器、发光二极管、光电探测器、量子点电视等光电子器件中的应用进展进行了概述，最后对其在光电器件领域的应用进行了展望。

近年来,过渡金属碲化物(TMTs)以其独特的晶体结构和优异的物化特性引起了科学界的广泛关注和研究.本文采用超声法制备CoTe2量子点(QDs),通过TEM、AFM、EDS、XPS、XRD、FTIR等技术手段对制备的CoTe2 QDs进行了形貌和结构的表征,同时使用分光光度计(UV-Vis)、光致发光谱(PL)和光致发光激发光谱(PLE)研究了CoTe2 QDs的光学性质.结果表明,制备得到的CoTe2 QDs分散性良好、粒径均匀、呈现球形形貌,晶粒的平均直径约为3.1 nm,平均高度约为2.9 nm;CoTe2 QDs在红外波段存在明显的吸收,吸收值随稀释浓度的增加而降低;当激发光波长和发射光波长依次增加时,PL和PLE峰出现红移,具有明显的Stokes位移效应,表明CoTe2 QDs的光致发光具有激发波长依赖性;CoTe2 QDs具有光致多色发光特性,不同激发光波长可发出不同颜色的光;荧光量子产率可达62.6％.CoTe2 QDs优异的光学特性尤其是在红外波段的吸收和发光特性,表明其在红外探测、激光防护涂层、荧光成像、多色发光和纳米光子器件等研究领域中具有重要的潜在应用价值,有望成为一种新型红外探测材料.

High-k HfOxNy and HfO2 have been applied to amorphous InGaZnO (a-IGZO) metal–oxide–semiconductor (MOS) capacitors as high-k gate dielectrics by using radio-frequency sputtering at room temperature. Effects of nitrogen incorporation on the optical band gap, band alignment and electrical properties of HfOxNy/IGZO/Si gate stacks have been systematically investigated by spectroscopic ellipsometry (SE), UV–vis spectroscopy, x-ray photoemission spectroscopy (XPS) and electrical measurements. Experimental results have confirmed the successful incorporation of nitrogen into HfO2 films and reduction in band gap with the incorporation of nitrogen for HfOxNy thin films. Reduction in valence band offset and increase in conduction band offset have been observed for HfOxNy/IGZO gate stack. Electrical properties measurements for a-IGZO MOS capacitors based on HfOxNy gate dielectrics have indicated that nitrogen incorporation leads to the improved interface quality, increased dielectric constant, reduced hysteresis voltage, and decreased leakage current density. Meanwhile, the leakage current mechanism under gate injection for MOS capacitors based on HfO2 and HfOxNy high-k gate dielectrics has been investigated systematically.

Current conduction mechanisms of Hf1-xTixO2-gated metal-oxide-semiconductor (MOS) capacitors depending on various post-annealing temperature (PDA) have been investigated. The sample subjected to 400 degrees C annealing exhibits superior performance with negligible hysteresis memory window shift (Delta V-fb = 0.005 V) and lowest gate leakage current density (5.4 x 10(-5) A/cm(-2) at V-g = 2 V). In addition, evolution of density of interface traps (D-it), border charger density (N-ot) and oxide charge density (Q(ox)) as a function of annealing temperature were investigated in details. Detailed electrical measurements reveal that the dominant current conduction behaviors are Poole-Frankel (P-F) emission in the region of low electric fields and Schottky Emission (SE) in the region of high electric fields for gate injection. For substrate injection, however, is mainly via Ohm's conduction, Schottky emission (SE) conduction mechanism serves in low applied field in the samples, respectively. (C) 2015 Elsevier B.V. All rights reserved.

The effects of substrate temperature (T-s) on the electrical and optical properties of amorphous InGaZnO thin films deposited by sputtering have been investigated. As T-s increased from RT to 400 degrees C, all the films remained amorphous, the transmission in the visible region increased from 92.8% to 93.54%, and the band gap decreased from 3.42 eV to 3.31 eV. Based on Cauchy-Urbach model, the optical properties of all samples were analyzed by spectroscope ellipsometry (SE) and increase in refractive index has been detected with the increase in Ts. Results of Hall measurement showed that substrate temperature have remarkable influence on the resistivity (rho), carrier concentration (n), and carrier mobility (mu) of IGZO films. As T-s increased from RT to 400 degrees C, rho decreased from 46.6 to 0.24 Omega cm, and then increased to 1.11 Omega cm at T-s of 400 degrees C, and n increase from 5.67 x 10(15) to 7.33 x 10(18) cm(-3). Investigation of X-ray photoelectron spectroscopy (XPS) indicated that as T-s increased, an O 1s component representing the oxygen vacancies increased in amount and that the intensity ratio of In/Ga increased but that of Zn/Ga decreased. The analysis suggests that the increase of oxygen vacancies could explain the increase in n and reduction in rho and that the compositional change could explain the change of E-g. (C) 2015 Elsevier B.V. All rights reserved.

•Band offsets in HfTiO/InGaZnO4 heterojunction were determined by XPS.•Valence band offset of HfTiO/IGZO heterojunction is determined to be 0.35eV.•Conduction band offset of 1.61eV is deduced for HfTiO/IGZO heterojunction.

The effect of nitrogen on the band offset of sputtering-derived InZnGaO4 (IGZO)/Si heterostructures has been systematically investigated by x-ray photoelectron spectroscopy (XPS) measurements. Elemental analysis indicates that nitrogen has been successfully incorporated into the IGZO film. By using In 3d5/2, In 3d3/2 and Ga 3d core level (CL) XPS spectra as references, values of valence band offsets (ΔEv) of have been determined to be 2.56 ± 0.02 and 2.44 ± 0.02 eV for IGZO/Si and IGZO:N/Si heterojunctions, respectively. Using the experimental band gap of 3.59 and 3.50 eV of the IGZO/Si and IGZO:N/Si, the calculated values of conduction band offset (ΔEc) is 0.09 ± 0.01 and 0.06 ± 0.01 eV, respectively. The results indicate that nitrogen incorporation leads to the reduction in band gap and ΔEv and the slight effect on the ΔEc has also been detected.

High-k gate dielectric HfTiOx thin films have been deposited on Si and quartz substrate by radio frequency (RF) magnetron sputtering. The structural and optical properties of HfTiOx thin films related to deposition power are investigated by X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), and spectroscopic ellipsometry (SE). Results indicate that the as-deposited HfTiOx thin films are amorphous state regardless of the deposition power. The increase of band gap of the samples is observed with the increase of deposition power. Moreover, the increase of the thickness, deposition rate, refractive index (n) and the decrease of the extinction coefficient with the increase of deposition power are also confirmed. Additionally, the electrical properties of films are analyzed by measurement of high frequency capacitance–voltage (C–V) and leakage current density-voltage (J-V) characteristics. And the leakage current conduction mechanisms are also discussed.

The effect of boron (B) doping on the microstructure, band gap energy and electrical properties of ZrO2 gate dielectrics deposited by sol–gel method at low temperature were systemically investigated. By means of characterization of spectroscopy ellipsometry and ultraviolet–visible spectroscopy, the thicknesses and optical constants of ZrO2 gate dielectrics have been determined precisely. The B incorporation dependent electrical properties of ZrO2 films were determined by capacitance–voltage (C–V) and leakage current density–voltage (J–V) measurements. The dominant conduction mechanisms of Al/B:ZrO2/n-Si MOS structures have been discussed systematically in detail. As a result, the optimized B incorporation content has been obtained to achieve ZrO2 gate dielectrics with high quality.

Sputtering-derived amorphous InGaZnO (a-IGZO) thin films were grown on Si and glass substrates in a mixed ambient of Ar and O-2 at fixed 0.5 Pa working pressure. The influence of O-2/Ar flow ratio on the optical and electrical properties of a-IGZO thin films has been systematically investigated by means of characterization from spectroscopic ellipsometry (SE), X-ray diffraction (XRD), scan electron microscopy (SEM), atomic force microscope (AFM), UV-vis spectroscopy, and electrical measurements. Results have shown that the band gap of the as-deposited IGZO films increases from 3.45 eV to 3.75 eV as the O-2/Ar flow ratio increases from 0% to 20%. Blue shift in band gap and reduction in reactive index with increasing the O-2/Ar flow ratio have been detected. Electrical measurements have indicated the increase in resistivity at higher O-2/Ar gas flow ratio. Related mechanics about the increase in band gap and resistivity have been discussed in detail. (C) 2014 Elsevier B.V. All rights reserved.

TiO2-doped HfO2 gate dielectric thin films have been deposited on Si(100) substrates by RF sputtering. The component, morphology, structure, optical and interfacial properties of Hf-1 xTixO2 films related to TiO2 concentration are systematically investigated by atomic force microscope (AFM), X-ray diffraction (XRD), spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and Fourier transformation infrared (FTIR). By employing Cauchy-Urbach model, the optical constants, such as refractive index (n), extinction coefficient (k), absorption coefficient (alpha), and optical band gap (E-g) have been determined precisely. Measurements from XRD have confirmed that TiO2 incorporating into HfO2 films leads to the increase of the crystallization temperature of HfO2 films with increasing the TiO2 concentration. SE analyses have indicated that reduction in band gap and refractive index has been observed with increasing the TiO2 component in Hf-1 xTixO2 films. The increase in Urbach parameter E-U with the increase of TiO2 concentration also suggests the rise in disorder for Hf-1 xTixO2 films. FTIR measurements for Hf-1 xTixO2/Si gate stack indicate the existence of the interfacial layer regardless of the TiO2 concentration. For the 9% TiO2-doped HfO2 samples, the shift in FTIR characteristic peak suggests the formation of the silicate layer, which leads to the suppressed interfacial layer growth during deposition. As a result, it can be conclude that the TiO2 component in Hf-1 xTixO2 films should be controlled precisely to guarantee interfacial properties of Hf-1 xTixO2/Si gate stacks. (C) 2014 Elsevier B.V. All rights reserved.

High-k gate dielectric HfO2 thin films have been deposited on Si and quartz substrate by radio frequency magnetron sputtering. The structural and optical properties of HfO2 thin films related to deposition power are investigated by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), atomic force microscopy (PPM), ultraviolet-visible spectroscopy (UV-Vis), and spectroscopic ellipsometry (SE). Results confirmed by XRD have shown that the as-deposited HfO2 thin films are not amorphous state but in monoclinic phase, regardless of deposition power. Analysis from FTIR indicates that an interfacial layer has been formed between the Si substrate and the HfO2 thin film during deposition. AFM measurements illustrate that the root mean square (RMS) of the as-deposited HfO2 thin films' surface demonstrates an apparent reduction with the increase of deposition. Combined with UV-Vis and SE measurements, it can be noted reduction in band gap with an increase in power has been observed. Additionally, increase in refractive index (n) has been confirmed by SE. (C) 2014 Elsevier B.V. All rights reserved.

High-k gate dielectric HfO2 thin films have been deposited on Si and quartz substrates by radio frequency magnetron sputtering. The structural characteristics, surface morphology, and optical properties of the HfO2/Si gate stacks at various post-annealing temperatures were examined by X-ray diffraction (XRD), atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis spectroscopy), and spectroscopic ellipsometry (SE). XRD measurement indicates that the 80 W-deposited HfO2 films demonstrate a polycrystalline structure. AFM measurements illustrate that the root mean square of the HfO2 thin films demonstrates an apparent increase with increasing the annealing temperature. Analysis from FTIR indicates that the Si–O–Si bonds vibration peak position shift toward lower wave numbers with increasing the annealing temperature. Combined with UV–Vis spectroscopy and SE measurements, it can be noted reduction in band gap with an increase in annealing temperature has been confirmed. Additionally, increase in refractive index (n) has been confirmed by SE.

Al2O3 high-k gate dielectric has been deposited onto a Si substrate by metalorganic-chemical-vapor-deposition (MOCVD) and then nitridized by NH3 annealing in a temperature range of 500-1000 degrees C. The effect of annealing temperature on the interfacial stability, morphology, and electrical properties of Al2O3/Si gate stack has been investigated. AFM analysis has indicated that uniform and smooth surface has been obtained by NH3 annealing. XPS measurements have confirmed that NH3 annealing leads to the formation of SiON interfacial layer and the nitridation of Al2O3 surface layer. Moreover, a decrease in band gap and valence band maximum with increasing annealing temperature has been detected. In addition, an optimized electrical performance based on Au/Al2O3/Si/AI CMOS capacitor has been obtained.

High-permittivity hafnium titanate (HfxTi1-xO2) films have been deposited on Si substrates by RF sputtering and subjected to rapid thermal annealing at various temperatures in air. Post annealing temperature dependent microstructure and optical properties of the HfxTi1-xO2 films were investigated by X-ray diffraction (XRD), spectroscopic ellipsometry (SE), atomic force microscope (AFM), and ultraviolet-visible spectroscope (UV-Vis). Analysis from XRD reveals that the as-deposited films are amorphous as well as those samples annealed at lower annealing temperature. However, with increasing annealing temperature, polycrystalline structure with highly (-111) preferential orientation appears. AFM results show that annealing leads to the increase in surface roughness. Combined with UV-Vis and SE measurements, red shift in band gap has been observed as a function of annealing temperature. Additionally, increase in optical constant has been confirmed by SE based on Cauchy-Urbach model.