Fabrication of ZnO thin film diode using laser annealing

A p-n homojunction was obtained by Nd:YAG laser annealing of Zn₃P₂/n-ZnO thin film. The deposition process of ZnO and Zn₃P₂ thin film was performed by pulsed laser deposition (PLD). A p-n junction was formed by Nd:YAG laser annealing of Zn₃P₂/n-ZnO thin film and showed typical I-V characteristics of a diode. Laser annealing could be a useful technique for the fabrication of an ultraviolet light-emitting diode or an ultraviolet laser diode.     

Influence of annealing on ZnO thin film grown by plasma-assisted MOCVD

ZnO films were grown on C-plane sapphire substrate by plasma-assisted MOCVD. The films was characterized by XRD, photoluminescence (PL) and the optical transmission spectrum. We found tensile strain in the sample, which had been annealed many times during the growth process, while there is compressive strain in the sample, which was annealed only one time after growth. The PL spectra at room temperature for the sample annealed many times exhibited only one emitting peak at around 380 nm. However, we find Γ₅ and Γ₆ free exciton peaks in the sample annealed only one time after growth. At the same time, the optical transmission indicate that the maximum of the sample's transmission decreases against with the increasing of the c-axis length in ranges from 190 to 900 nm.     

The effect of annealing on the semiconductor in a thin film transistor

This study is concerned with an investigation of the effect of temperature annealing on the CdSe semiconductor in a thin film transistor. Electron microscopy shows that the CdSe film is polycrystalline. Annealing results in the growth of the crystallites until, for working thin film transistors, the crystallite size distribution becomes a log-normal one, with a mean crystallite size approximately equal to the thickness of the film. Annealing reduces the energy stored in the CdSe by converting grain boundaries from high to low angle ones and by reducing the grain boundary area.     

Enhanced acetone detection using Au doped ZnO thin film sensor

Zinc oxide (ZnO) thin films are prepared using sol–gel method for acetone vapor sensing. Zinc acetate dihydrate (Zn(CH₃COO)₂·2H₂O) was taken as starting material and a stable and homogeneous solution was prepared in ethanol by deliquescing the zinc acetate and distinct amount of monoethanolamine as a stabilizing agent. The prepared solution was then coated on silicon substrates by spin coating method and then annealed at 650 °C for preparing ZnO thin films. The thickness of the film was maintained at 410 nm. The structural, morphological and optical studies were done for the synthesized ZnO thin films. The operating temperature and sensor response is considered to be an important parameter for the gas sensing behavior of any material. Therefore, the present study examined the effect of sensing behavior of 3% v/v gold (Au) doped ZnO thin films as a sensor. The response characteristics of 410 nm ZnO thin film for temperature ranging from 180 to 360 °C were determined for the acetone vapors. The reported study provides a significant development towards acetone sensors, where a very high sensitivity with rapid response and recovery times are reported with lowered optimal operating temperature as compared to bare ZnO nano-chains like structured thin films. In comparison to the bare ZnO thin films giving a response of 63 at an operating temperature of 320 °C, a much better response of 132.3 was observed for the Au doped ZnO thin films at an optimised operating temperature of 280 °C for a concentration of 500 ppm of acetone vapors.     

Effect of annealing on molybdenum doped indium oxide thin films RF sputtered at room temperature

Thin films of molybdenum doped indium oxide (IMO) were deposited on glass at room temperature using an in-built three-source RF magnetron sputtering. The films were studied as a function of oxygen volume percentage (O₂ vol. %; ranging from 0.0 to 17.5%) in the sputtering chamber. The as-deposited amorphous films were crystallized on post-annealing. The as-deposited films are low conducting and Hall coefficients were undetectable; whereas post-annealed films possess fairly high conductivity. The lowest transmittance (11.96% at 600 nm) observed from the films deposited without oxygen increased to a maximum of 88.01% (3.5 O₂ vol. %); whereas this transmittance was decreased with the increasing O₂ vol. % to as low as 81.04% (15.6 O₂ vol. %); a maximum of 89.80% was obtained from the films annealed at 500 °C in open air (3.5 O₂ vol. %). The optical band gap of 3.80 eV obtained from the films deposited without oxygen increased with increasing O₂ vol. % to as high as 3.91 eV (17.5 O₂ vol. %). A maximum of 3.92 eV was obtained from the films annealed at 300 °C in N₂:H₂ gas atmosphere (17.5 O₂ vol. %).     

Investigation of the substrate effect for Zr doped ZnO thin film deposition by thermionic vacuum arc technique

ZnO is a fundamental wide band gap semiconductor. Especially, doped elements change the optical properties of the ZnO thin film, drastically. Doped ZnO semiconductor is a promising materials for the transparent conductive oxide layer. Especially, Zr doped ZnO is a potential material for the high performance TCO. In this paper, ZnO semiconductors were doped with Zr element and microstructural, surface and optical properties of the Zr doped ZnO thin films were investigated. Zr doped ZnO thin films were deposited thermionic vacuum arc (TVA) technique. TVA is a rapid and high vacuum deposition method. A glass, polyethylene terephthalate and Si wafer (111) were used as a substrate material. Zr doped ZnO thin films deposited by TVA technique and their substrate effect investigated. As a results, deposited thin films has a high transparency. The crystal orientation of the films are in polycrystal formation. Especially, substrate crystal orientation strongly change the crystal formation of the films. Substrate crystal structure can change the optical band gap, microstructural properties and deposited layer formation. According to the atomic force microscopy and field emission scanning electron microscopy measurements, all deposited layer shows homogeneous, compact and low roughness. The band values of the deposited thin film were approximately found as to be 3.1–3.4 eV. According to the results, Zr elements created more optical defect and shifted to the band gap value towards to blue region.     

The effect of annealing on amorphous indium gallium zinc oxide thin film transistors

This paper presents the post-annealing effects, caused by rapid thermal annealing (RTA), on amorphous indium gallium zinc oxide (a-IGZO) thin film transistor's (TFT) electrical characteristics, and its contact resistance (R_C) with thermally grown SiO₂ gate dielectric on silicon wafer substrates. The electrical characteristics of two types of TFTs, one post-annealed and the other not, are compared, and a simple model of the source and drain contacts is applied to estimate the R_C by a transmission line method (TLM). Consequently, it has been found that the post-annealing does improve the TFT performances; in other words, the saturation mobility (μ_sat), the on/off current ratio (I_ON/OFF), and the drain current (I_D) all increase, and the R_C and the threshold voltage (V_T) both decrease. As-fabricated TFTs have the following electrical characteristics; a saturation mobility (μ_sat) as large as 0.027 cm²/V s, I_ON/OFF of 10³, sub-threshold swing (SS) of 0.49 V/decade, V_T of 32.51 V, and R_C of 969 MΩ, and the annealed TFTs have improved electrical characteristics as follows; a μ_sat of 3.51 cm²/V s, I_ON/OFF of 10⁵, SS of 0.57 V/decade, V_T of 27.2 V, and R_C of 847 kΩ.     

退火对溅射ZnO薄膜的形貌和内应力的影响

用超高真空射频磁控溅射技术制备了高C轴取向的ZnO薄膜,用扫描电镜和X射线衍射仪分别研究了退火对ZnO薄膜形貌和内应力的影响.结果表明:适当温度退火后薄膜的形貌和内应力得到改善,通过增氧、缺陷原子的热激活和晶粒融合等可以有效地降低薄膜中由热效应、缺陷效应和粒子注入效应等引起的张应力,薄膜组织致密化并且柱状晶粒取向趋于一致.450℃退火的ZnO薄膜具有最低的张应力和最佳的结晶质量.     

Mn、Co掺杂ZnO薄膜结构及发光特性研究

利用脉冲激光沉积(PLD)方法在Si(100)衬底上制备了ZnO、Zn0.8Mn0.2O、Zn0.8Co0.2O薄膜.薄膜的晶体结构和表面形貌采用X射线衍射仪和原子力显微镜测试.表明薄膜具有明显的c轴择优生长取向,薄膜表面较为平整,颗粒尺寸在纳米量级,薄膜中晶粒的生长模式为"柱状"模式.此外,Mn、Co掺入后,薄膜的X射线衍射峰有小角度偏移,这与 Mn2 、Co2 离子半径有关.PL谱显示Mn、Co掺杂ZnO薄膜的蓝、绿发光峰的位置相对纯的ZnO薄膜没有改变,还出现了紫外发光峰,其中Mn掺杂的蓝、绿光峰的强度减弱,Co掺杂的蓝光峰强度减弱,绿光峰强度增强.这是因为Mn、Co掺入改变了ZnO本征缺陷的浓度,发光峰的强度也随之而改变.     

The effect of annealing ambient on the characteristics of an indium-gallium-zinc oxide thin film transistor

In this study, the effects of different annealing conditions (air, O2, N2, vacuum) on the chemical and electrical characteristics of amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFT) were investigated. The contact resistance and interface properties between the IGZO film and the gate dielectric improved after an annealing treatment. However, the chemical bonds in the IGZO bulk changed under various annealing atmospheres, which, in turn, altered the characteristics of the TFTs. The TFTs annealed in vacuum and N2 ambients exhibited undesired switching properties due to the high carrier concentration (>10(17) cm(-3)) of the IGZO active layer. In contrast, the IGZO TFTs annealed in air and oxygen ambients displayed clear transfer characteristics due to an adequately adjusted carrier concentration in the operating range of the TFT. Such an optimal carrier concentration arose through the stabilization of unstable chemical bonds in the IGZO film. With regard to device performance, the TFTs annealed in O2 and air exhibited saturation mobility values of 8.29 and 7.54 cm2/Vs, on-off ratios of 7.34 x 10(8) and 3.95 x 10(8), and subthreshold swing (SS) values of 0.23 and 0.19 V/decade, respectively. Therefore, proper annealing ambients contributed to internal modifications in the IGZO structure and led to an enhancement in the oxidation state of the metal. As a result, defects such as oxygen vacancies were eliminated. Oxygen annealing is thus effective for controlling the carrier concentration of the active layer, decreasing electron traps, and enhancing TFT performance.     

热处理对金属薄膜压阻灵敏度的影响

采用磁控溅射法制备锰铜薄膜,溅射和真空蒸发法制备镱薄膜.对热处理前后薄膜的电学性能、微观形貌和结构进行了表征,并采用轻气炮和对顶砧装置对薄膜传感器进行了压阻性能测试,结果表明热处理后薄膜的压阻系数有很大提高.SEM和XRD的分析表明,压阻系数的提高是由于热处理后薄膜晶粒长大、缺陷减少、电阻率下降所致.敏感薄膜的电阻率与传感器的灵敏度直接相关.热处理后,薄膜压阻计的灵敏度已接近箔式传感器的水平,热处理是提高薄膜压阻计灵敏度的有效手段.     

The effect of thermal annealing on pentacene thin film transistor with micro contact printing

We used micro contact printing (micro-CP) to fabricate inverted coplanar pentacene thin film transistors (TFTs) with 1-microm channels. The patterning of micro-scale source/drain electrodes without etch process was successfully achieved using Polydimethylsiloxane (PDMS) elastomer stamp. We used the Ag nano particle ink as an electrode material, and the sheet resistance and surface roughness of the Ag electrodes were effectively reduced with the 2-step thermal annealing on a hotplate, which improved the mobility, the on-off ratio, and the subthreshold slope (SS) of the pentacene TFTs. In addition, the device annealing on a hotplate in a N2 atmosphere for 30 sec can enhance the off-current and the mobility properties of OTFTs without damaging the pentacene thin films and increase the adhesion between pentacene and dielectric layer (SiO2), which was investigated with the pentacene films phase change of the XRD spectrum after device annealing.     

掺杂ZnO薄膜研究

采用电子束蒸发方法在玻璃衬底上制备ZnO薄膜和掺杂ZnO薄膜.通过X射线衍射、台阶仪及Hall效应等测试研究了衬底温度和掺杂对晶体质量和电学性能的影响,发现原位生长的ZnO薄沿c轴择优生长,且掺杂ZnO薄膜具有低达3.029×10-4Ω·cm的电阻率.     

The effect of annealing on properties of europium doped ZnO nanopowders obtained by a microwave hydrothermal method

Europium doped ZnO nanopowders made by microwave hydrothermal method are investigated. As zinc oxide precursor zinc nitrate(V) hexahydrate (Zn(NO₃)₂·6H₂O) was used. Two types of nanopowder samples are examined: as grown and annealed at 750 °C in air atmosphere. We investigate the structural, morphological and optical prosperities of europium doped ZnO. Results of scanning electron microscopy, X-ray diffraction, photo- and cathodoluminescence investigations and also CIE1961 chromaticity diagram are presented.     

退火对氧化锌薄膜结晶性能的影响

采用射频磁控溅射法在(001)硅片上制备了ZnO薄膜,利用X射线衍射对薄膜的制备工艺进行了研究,结果表明,基板温度、溅射功率、氩氧比、总气压在一个较大的范围内变化时都可实现薄膜的c轴择优取向生长.随后对薄膜进行了空气退火并利用摇摆曲线表征薄膜的结晶质量,摇摆曲线的半高宽随退火温度的提高而减小,700℃退火后FWHM为2.5°.     

Effect of pulsed laser annealing on optical and structural properties of ZnO:Eu thin film

Journal of Materials Science - ZnO:Eu thin film fabricated by pulsed laser deposition was treated by pulsed UV laser. The effect of laser fluence from 70 to 125 mJ cm?2 on film...     

Structural, optical and non-linear optics properties of highly doped molybdenum indium oxide thin film

Molybdenum (Mo)-doped In₂O₃ thin film with 10 wt% was successfully prepared by evaporation method. After annealing at 600 °C the film changes it colour from very dark to a clear transparent film. SEM and AFM analysis reveal that the film is continuous with high metallic coverage >98 % and exhibits a granular structure with typical grain size of 50 nm. More interestingly, the film shows more than 90 % transparency from visible to near infrared region and with wide optical band gap of 4.26 eV. The widening of the band gap is due to the Burstein–Möss (BM) effect as Mo will occupy In sites within the structure of the film thus increasing the carrier concentration thus enhancing its electrical properties. The nonlinear optical properties of Mo-doped In₂O₃ film with glass substrate were investigated using z-scan technique. Under cw excitation the film exhibits large reverse saturation absorption and negative nonlinearities. The real and imaginary parts of third order susceptibility of the film were measured and found that the imaginary part which arises from the change in absorption is dominant.     

退火温度对RF磁控溅射ZnO薄膜力学性能的影响

采用X射线衍射分析(XRD),原子力显微镜(AFM)及纳米压痕技术测试分析了多晶ZnO薄膜的晶格结构和力学性能.薄膜的制备采用了射频(RF)磁控溅射方法,并分别在不同温度下进行了退火处理.XRD分析显示随着退火温度的上升,薄膜的晶粒尺寸逐步增大,且C轴取向显著增强.压痕测试结果表明,由于尺寸效应的影响,硬度随退火温度的变化有明显的趋势,从2.5GPa(常温下)逐步增加到5.5GPa(4500C),随着温度的进一步上升,硬度值又逐步下降到4.5GPa(650℃).弹性模量整体随退火温度的变化并不呈现明显的规律,但在450℃和200℃下退火分别有最大值26.7GPa和最小值21.5GPa,这是由于尺寸效应与晶格取向的双重作用的结果.测试结果表明适当的退火处理对ZnO薄膜的结晶品质与力学性能有明显的改善.     

The recent advances of research on p-type ZnO thin film

ZnO is a direct wide-band gap (3.37 eV) compound semiconductor with large exciton binding energy (60 meV) at room temperature. Therefore it has a strong potential for various short-wavelength optoelectronic device, and now attracts tremendous renew interests for developing highly efficient ZnO-based optoelectronic devices. While high quality ZnO p–n junction materials obtained is the key step of its optoelectronic application. Whereas ZnO thin film is naturally only n-type conductivity due to a large number of native defects, such as oxygen vacancies and zinc interstitials, which lead to difficulty in achieving p-type ZnO thin film. Therefore the fabrication of p-type ZnO thin film has been a key and hotspot of the research on ZnO. This article summarizes the recent advances of the studies on p-type ZnO thin film and the correlative several important breakthroughs in ZnO homo-junction devices based on succeeding on fabrication of p-type ZnO film. Although the achievement obtained as summarized, there is also a long way from the real application of ZnO-based optoelectronic device. We here also discuss the problem and relevant possible solution for the fabrication of p-type ZnO film and its optoelectronic application. And forecast the preparation trends of p-type ZnO thin film.     

The effect of substrate temperature on Al-doped ZnO characteristics for organic thin film transistor applications

The influence of substrate temperature on the structural, electrical, and optical properties of aluminum-doped zinc oxide (AZO) films fabricated by radio frequency (RF) magnetron sputtering was investigated. The AZO films were deposited at various substrate temperatures, and the effect of AZO gate electrode conductivity on organic thin film transistor (OTFT) performance was examined. While an increase in the substrate temperature from 100 °C to 300 °C led to an improvement in crystallinity, substrate temperatures over 300 °C caused degradation of the electrical and surface properties. We fabricated OTFTs using AZO films prepared at various substrate temperatures and obtained good device performance. Thus, the performance of an OTFT can be determined by the conductivity of the AZO gate electrode.