Morphological study of thin films: Simulation and experimental insights using horizontal visibility graph

We studied the morphological nature of various thin films such as silicon carbide (SiC), diamond (C), germanium (Ge), and gallium nitride (GaN) on silicon substrate Si(100) using the pulsed laser deposition (PLD) method and Monte Carlo simulation. We, for the first time, systematically employed the visibility algorithm graph to meticulously study the morphological features of various PLD grown thin films. These thin-film morphologies are investigated using random distribution, Gaussian distribution, patterned heights, etc. The nature of the interfacial height of individual surfaces is examined by a horizontal visibility graph (HVG). It demonstrates that the continuous interfacial height of the silicon carbide, diamond, germanium, and gallium nitride films are attributed to random distribution and Gaussian distribution in thin films. However, discrete peaks are obtained in the brush and step-like morphology of germanium thin films. Further, we have experimentally verified the morphological nature of simulated silicon carbide, diamond, germanium, and gallium nitride thin films were grown on Si(100) substrate by pulsed laser deposition (PLD) at elevated temperature. Various characterization techniques have been used to study the morphological, and electrical properties which confirmed the different nature of the deposited films on the Silicon substrate. Decent hysteresis behavior has been confirmed by current-voltage (IV) measurement in all the four deposited films. The highest current has been measured for GaN at ～60 nA and the lowest current in SiC at ～30 nA level which is quite low comparing with the expected signal level (μA). The HVG technique is suitable to understand surface features of thin films which are substantially advantageous for the energy devices, detectors, optoelectronic devices operating at high temperatures.     

我国IC产业发展状况分析

本文分析了集成电路及其相关技术的现状和发展趋势。分析了国内集成电路产业状况和面临的课题。     

可编程逻辑器件安全性漏洞检测平台设计与实现

芯片作为信息存储、传输、应用处理的基础设备,其安全性是信息安全的一个重要组成部分。可编程逻辑器件安全性漏洞检测平台正是为了检测出逻辑芯片内可能存在的攻击后门和设计缺陷而研制的,从而确保电子设备中信息安全可靠。文章研究可编程逻辑器件漏洞检测平台的设计与实现,简要介绍了检测平台的总体结构和运行机制,给出了检测平台的总体设计思想、实现方案及系统组成,并深入研究了漏洞检测平台设计与实现所涉及的相关技术。     

脉冲激光沉积VN/Ag复合薄膜的组织及摩擦学性能研究

利用脉冲激光沉积技术制备了不同Ag含量的VN/Ag复合薄膜,利用扫描电子显微镜、X射线衍射仪、纳米力学测试系统等设备表征薄膜的组织结构、成分、表面形貌及力学性能,利用UMT-3摩擦试验机考察薄膜在室温至900℃下的摩擦学性能。结果表明,随着Ag含量的增多,薄膜的组织形貌变差,硬度及弹性模量降低。当Ag含量为16%(原子分数)时薄膜在试验温度范围内的摩擦学性能最佳。由于Ag在低温的润滑特性及高温摩擦化学反应生成了新的润滑相,如V2O5、V6O11、V6O13、Ag3VO4、AgVO3等,使得摩擦系数随温度的升高而逐渐降低,在900℃下取得最低值0.08,实现了宽温域内的连续润滑。     

可编程逻辑器件(PLD)在矩阵变换器中的应用

本文根据矩阵变换器主电路换流的要求,阐述了应用四步换流策略的合理性和可行性,设计了与换流相关的电路。并利用PLD器件替代分立器件设计了控制模块。PLD器件依据空间向量算法,将PWM信号和输入电流扇区信号、输出电压扇区信号等进行组合逻辑运算得到开关组合及其导通顺序,并按四步换流策略将脉冲分配到对应开关,完成了开关的通断操作。分析表明,四步换流策略消除了对电路可能造成的危害。文章最后讨论了与换流有关的两个问题,并给出了实验波形图。     

EDA设计技术与方法(Ⅰ)──EDA方法及其进展

ＥＤＡ是现代电子学的标志。本研究对 ＥＤＡ设计方法及其发展进行了综述。     

可编程逻辑器件(PLD)在电路设计中的应用

提出了可编程逻辑器件（PLD）在电路设计中的应用,介绍了在线可编辑（ISP）的原理。结合电力系统通用控制器的设计,介绍了Altera公司的MAX7000系列的EPLD和开发工具软件MaxplusII的使用。     

Effect of Ga doping on micro/structural, electrical and optical properties of pulsed laser deposited ZnO thin films

Undoped and Ga doped ZnO thin films (1% GZO, 3% GZO and 5% GZO) were grown on c-Al₂O₃ substrates using the 1, 3 and 5 at. wt.% Ga doped ZnO targets by pulsed laser deposition. X-ray diffraction studies revealed that highly c-axis oriented, single phase, undoped and Ga doped ZnO thin films with wurtzite structure were deposited. Micro-Raman scattering analysis showed that Ga doping introduces defects in the host lattice. The E₂^High mode of ZnO in Ga doped ZnO thin film was observed to shift to higher wavenumber indicating the presence of residual compressive stress. Appearance of the normally Raman inactive B₁ modes (B₁^Low, 2B₁^Low and B₁^High) due to breaking of local translational symmetry, also indicated that defects were introduced into the host lattice due to Ga incorporation. Band gap of the Ga doped ZnO thin films was observed to shift to higher energy with the increase in doping concentration and is explicated by the Burstein-Moss effect. Electrical resistivity measurements of the undoped and GZO thin films in the temperature range 50 to 300 K revealed the metal to semiconductor transition for 3 and 5% GZO thin films.     

Highly transparent conductive and near-infrared reflective ZnO:Al thin films

Al-doped ZnO (AZO) thin films have been prepared on glass substrates by pulsed laser deposition. The structural, optical, and electrical properties were strongly dependent on the growth temperatures. The lowest resistivity of 4.5 × 10⁻⁴ Ωcm was obtained at an optimized temperature of 350 °C. The AZO films deposited at 350 °C also had the high optical transmittance above 87% in the visible range and the low transmittance (<15% at 1500 nm) and high reflectance (∼50% at 2000 nm) in the near-IR region. The good IR-reflective properties of ZnO:Al films show that they are promising for near-IR reflecting mirrors and heat reflectors.