Organic photovoltaics using thin gold film as an alternative anode to indium tin oxide

Indium Tin Oxide (ITO) is the most commonly used anode as a transparent electrode and more recently as an anode for organic photovoltaics (OPVs). However, there are significant drawbacks in using ITO which include high material costs, mechanical instability including brittleness and poor electrical properties which limit its use in low-cost flexible devices. We present initial results of poly(3-hexylthiophene): phenyl-C₆₁-butyric acid methyl ester OPVs showing that an efficiency of 1.9% (short-circuit current 7.01 mA/cm², open-circuit voltage 0.55 V, fill factor 0.49) can be attained using an ultra thin film of gold coated glass as the device anode. The initial I-V characteristics demonstrate that using high work function metals when the thin film is kept ultra thin can be used as a replacement to ITO due to their greater stability and better morphological control.     

Sputtered nickel oxide thin film for efficient hole transport layer in polymer-fullerene bulk-heterojunction organic solar cell

Bulk-heterojunction (BHJ) organic photovoltaics (OPV) are very promising thin film renewable energy conversion technologies due to low production cost by high-throughput roll-to-roll manufacturing, an expansive list of compatible materials, and flexible device fabrication. An important aspect of OPV device efficiency is good contact engineering. The use of oxide thin films for this application offers increased design flexibility and improved chemical stability. Here we present our investigation of radio frequency magnetron sputtered nickel oxide (NiO_x) deposited from oxide targets as an efficient, easily scalable hole transport layer (HTL) with variable work-function, ranging from 4.8 to 5.8 eV. Differences in HTL work-function were not found to result in statistically significant changes in open circuit voltage (V_oc) for poly(3-hexylthiophene):[6,6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PCBM) BHJ device. Ultraviolet photoemission spectroscopy (UPS) characterization of the NiO_x film and its interface with the polymer shows Fermi level alignment of the polymer with the NiO_x film. UPS of the blend also demonstrates Fermi level alignment of the organic active layer with the HTL, consistent with the lack of correlation between V_oc and HTL work-function. Instead, trends in j_sc, V_oc, and thus overall device performance are related to the surface treatment of the HTL prior to active layer deposition through changes in active layer thickness.     

Low-power gas sensors based on work-function measurement in low-cost hybrid flip–chip technology

To implement low-power gas sensors with low component costs, the principle of work-function read out via a hybrid suspended gate FET (SGFET) is being pursued, whereby a freely selectable sensor film undergoes a reversible work-function change corresponding to the build-up of a potential difference on the surface in response to gas adsorption/reaction. This is read out via an ISFET structure. An innovative design which allows cheap manufacturing will be described for the principle that has already been successfully demonstrated. The starting point of the design is a ceramic Al₂O₃ substrate coated with conductor patterns and sensitive materials onto which the FET is mounted in flip–chip technology. By means of the freely selectable sensor film and its preparation method, a wide range of applications can be opened up.     

功率放大器的自适应预失真线性化技术

重点介绍了几种主要的功率放大器的自适应预失真技术,包括基带预失真、中频预失真及射频预失真技术,以及几种自适应预失真工作函数的产生方法,并利用多项式产生工作函数的方法对功率放大器进行预失真调整,使其线性度得到明显改善。     

Gold and platinum as ozone sensitive layer in work-function gas sensors

Hybrid suspended gate FET (HSGFET) devices with a sensitive layer of platinum or gold were proven to be well-suited as reproducible ozone detection from the low ppb region up to 500 ppb and higher. Operating at 130°C, gold shows a nearly linear dependence on ozone concentration with high signals and a small humidity influence. Platinum at 130°C convinces with a fast response time and low cross sensitivities to other gases.     

Impact of gate metal work-function engineering for enhancement of subthreshold analog/RF performance of underlap dual material gate DG-FET

This work presents a systematic comparative study of analog/RF performance for underlap dual material gate (U-DMG) DG NMOSFET. In previous works, improved device performances have been achieved by use of high dielectric constant (k) spacer material. Although high-k spacers improve device performance, the intrinsic gain of the device reduces. For the analog circuits applications intrinsic gain is an important parameter. Hence, an optimized spacer material having dielectric constant, k = 7.5 has been used in this study and the gain is improved further by dual-material gate (DMG) technology. In this paper we have also studied the effect of gate material having different work function on the U-DMG DG NMOSFETs. This device exploits a step function type channel potential created by DMG for performance improvement. Different parameters such as the transconductance (g_m), the gain per unit current (g_m/I_ds), the intrinsic gain (g_mR_o), the intrinsic capacitance, the intrinsic resistance, the transport delay and, the inductance of the device have been analyzed for analog and RF performance analysis. Analysis suggested that the average intrinsic gain, g_m/I_d and g_m are increase by 22.988%, 16.10% and 27.871% respectively compared to the underlap single-material gate U-DG NMOSFET.     

Investigation and comparison of analog figures-of-merit for TFET and FinFET considering work-function variation

This paper investigates and compares the impacts of metal-gate work-function variation on important analog figures-of-merit (FOMs) for TFET and FinFET devices using 3-D atomistic TCAD simulations. Our study indicates that, at 0.6 V supply voltage and 0.2 V gate-voltage overdrive, TFET exhibits superior variation immunity regarding transconductance to drain–current ratio (g_m/I_DS), output resistance (R_out) and intrinsic gain, and comparable variability in g_m and cutoff frequency (f_T) as compared with the FinFET counterparts. In addition, how the correlations between pertinent parameters (e.g., g_m and R_out) impact the variation immunity of important analog FOMs are analyzed. Our study may provide insights for low-voltage analog design using TFET/FinFET technologies.     

SOI／SDB超薄膜全耗尽隐埋n沟MOSFET的解析模型

本文给出了基于SDB材料的无PN结超薄膜全耗尽隐埋n沟型MOSFET的较明确的物理模型,详细分析了它的导电机理,给出了解析表达式.并将本模型的计算结果与实验结果进行了比较,同时进行了一些讨论.     

复合多晶硅栅LDMOS的设计

提出了一种应用于射频领域的复合多晶硅栅LDMOS结构,并提出了具体的工艺实现方法。此结构采用栅工程的概念,设计的栅由S-gate和D-gate两块并列组成,S-gate用高功函数P型多晶硅材料,D-gate用低功函数N型多晶硅材料。MEDICI模拟结果表明,该结构能够降低沟道末端和漏极附近的最高电场强度,提高器件的跨导和截止频率;同时,还能够提高器件的击穿电压,并减小器件的热载流子效应。