有机半导体薄膜三极管的研制

采用真空蒸镀法和有机半导体材料酞菁铜,制作Au/CuPc/Al/ CuPc/Au三明治结构的肖特基型栅极有机静电感应三极管.该三极管导电沟道垂直于CuPc薄膜,与采用MOSFET结构的有机薄膜三极管相比导电沟道大幅缩短,有利于克服有机半导体电学性能的缺点.实验结果表明,该三极管驱动电压低,呈不饱和电流-电压特性.其工作特性依赖于栅极电压和梳状铝电极的结构.通过合理设计、制作梳状铝电极,获得了良好的三极管静态、动态特性.     

酞菁铜有机静电感应三极管动作特性研究

介绍了由有机半导体材料酞菁铜制作的具有Au/CuPc/Al/CuPc/Au三明治结构的肖特基型栅极有机静电感应三极管.根据对该三极管测试,采用适当的数学工具,对其参数进行计算.通过Ⅰ-Ⅴ方程的拟合,对其动作特性进行了研究.通过对小信号等效电路模型的仿真计算,得出其截止频率,并提出了改善其动作特性的途径.     

一种用于生物检测的半导体电场效应传感器

设计了一种简化的铝栅MOS半导体器件制作工艺流程,用6张掩模版成功制作出了基于表面电场效应原理的生物检测硅芯片传感器,采用SiO2-Si3N4复合栅介质层及耗尽型器件结构,以增强器件的识别与检测灵敏度。该传感器与常规铝栅MOS晶体管相比,去除了介质层表面的栅极导电层,代之以自组装技术制作生物薄膜并辅以栅参考电极作为控制栅极。用所制作的硅芯片传感器检测了相关生物蛋白质的电流响应,给出了该电流响应与器件沟道长度和沟道电阻及生物蛋白浓度等参数的关系,得到了较为满意的检测数据,达到了预期的基于表面电场效应的硅传感器制作和生物检测的目的。     

基于沟道及电极修饰的酞菁铜场效应晶体管的性能提高研究

利用对四联苯p -4P 以及五氧化二钒V2O5同时修饰导电沟道及源/漏电极,大幅 提高了基于酞菁铜CuPc场效应晶体管的性能。本文通过在绝缘层SiO2和有源层CuPc 之间插入p-4p缓冲薄层,同时在源/漏电极Al与有机半导体之间引入电极修饰层V2O5, 使得CuPc场效应晶体管的饱和迁移率和电流开/关比分别提高到5×10-2cm2 / V s和 104。p -4P能够诱导p型CuPc形成高度取向的连续薄膜,使得载流子能够在有源层中 更好地传输;而V2O5能够调节载流子的注入势垒,并可有效地降低沟道接触电阻(Rc)。 此方法能够在降低器件制备成本的前提下,大幅提高器件的性能。     

CuPc有机薄膜晶体管稳定性研究

以酞菁铜为有源层,二氧化硅为绝缘层,钛/金作为电极,制作了沟道宽长比为6 000/10的有机薄膜晶体管。通过比较在不同时期器件在空气环境中的电学特性,分析了环境对器件电学性能的影响。结果表明,在其他条件不变的情况下,当器件置于空气中时,其载流子的浓度和体电导率逐渐增大,迁移率几乎不受影响;相同栅极电压下器件达到饱和状态所需的源漏电压增大,线性区向饱和区推进;阈值电压减小,在栅极电压为0时,界面处逐渐形成导电沟道,器件从增强型向耗尽型转变。     

低温ITO薄膜制备及其在TOLED中的应用

通过在直流磁控溅射过程中加入微量水蒸气的方法,在低于60℃温度条件下制备了具有优良光电性能的透明导电ITO薄膜,并探讨了溅射功率、基板温度对ITO薄膜光电性能的影响.利用制得的ITO薄膜作电极,制作了结构为ITO/CuPc/NPB/Alq3/BCP/Mg:Ag/ITO的透明有机电致发光器件(TOLEDs),结果表明,器件的平均透过率达到45%;在驱动电压15 V的条件下,发光亮度达到了3000 cd/m2.     

电泳淀积三极管结构的碳纳米管场发射显示阴极

本研究探索了一种电泳选域组装碳纳米管发射器到正栅极结构的衬底中作为三极管结构的场发射显示阴极的工艺.在这个工艺中,悬浊液中的碳纳米管在施加于栅极电极和阴极电极的电压的作用下移向并淀积到三极管结构的衬底中.同时,这个栅极电极的正电压能够排斥悬浊的碳纳米管,使栅极电极不吸附碳纳米管.实验结果表明,碳纳米管选域组装到栅极孔洞中去,并且每一个孔洞中碳纳米管具有相同的组装密度.该工艺成本低、可实现大面积阴极的制备,是一种在制备三极管型碳纳米管场发射显示阴极中可供选择的工艺.     

电泳工艺制备阵列场发射阴极及其性能的研究

碳纳米管是理想的场发射冷阴极材料,阴极的图形阵列化是实现碳纳米管场发射显示器动态全彩视频显示的核心.三极管结构能够更好地进行矩阵寻址显示图像,且与常规的驱动电路相兼容,降低整体平板显示器件的制作成本.从实验出发,探索利用简单的电泳工艺制备图形化碳基薄膜阴极,采用与阴极成同一水平面的栅极的三极管结构,并对电泳的实验参数进行优化以提高阴极电压电流特性和发射的均匀性等问题,为场发射器件的制造提供优良的工艺基础.研究机械球磨和稀释悬浊液浓度对碳纳米管沉积均匀性的影响.实验结果表明稀薄的悬浊液的条件下可以在玻璃的银浆导电层上沉积较薄而均匀的碳纳米管膜,与丝网印刷工艺制备的阴极相比,均匀性更好,厚度更容易控制,具有更好的发射均匀性.测试图形化的阵列碳纳米阴极的三极管结构的场发射特性,发现当阳极电压保持在600 V,栅极电压接近500 V时,阳极电流能达到2.6 mA/cm2.荧光粉发光均匀,相比二极管结构具有更低的阈值电压,在亮度、均匀性和稳定性方面都有显著的优势.     

一种新型鳍状栅极LDMOS功率器件的设计

本文设计了一种具有新型鳍状栅极结构的LDMOS功率开关器件(FG-LDMOS),该器件在导电沟道处纵向刻蚀一组浅沟槽,再经热氧化后填充作为场板的多晶硅。鳍状栅极结构在不改变器件尺寸情况下,增大了沟道的有效宽度,增强了场板效应。通过Silvaco TCAD仿真验证,结果表明FG-LDMOS较传统LDMOS具有更好的电学特性,如击穿电压提高了25％达到100 V,比导通电阻Ron.sp降低了25％至2.68 mΩ?cm2,品质因数FOM提高了94.5％到3.58 MW/cm2。此外该FG-LDMOS拥有优异的高频开关特性,其栅漏电容CGD降到了0.46×10-16 F/μm,跨导gm升至0.26 mS。     

一种新型的CMOS集成湿度传感器

利用MEMS技术,对一种新型CMOS湿度传感器进行理论分析、模拟以及结果讨论.该湿度传感器采用标准CMOS工艺制造,采用梳状铝电极结构、梳状多晶硅加热结构,衬底接地,感湿介质采用聚酰亚胺,利用商业软件Coventor进行模拟绘制出敏感电容与相对湿度的曲线图.接口电路采用开关电容电路,输出可测电压信号,利用Microsim公司的Pspice模拟电路得到相对湿度与输出电压曲线关系.     

Copper phthalocyanine based vertical organic field effect transistor with naturally patterned tin intermediate grid electrode

We report on low voltage vertical organic field effect transistors using crosslinked poly(vinyl alcohol) (cr-PVA) as gate insulator and copper phthalocyanine (CuPc) as channel semiconductor. Al is used as gate and drain electrode. Sn thin films deposited under proper conditions are used as intermediate grid electrode (source), since the Sn film morphology simultaneously shows pinholes and lateral intergrain connectivity, allowing in-plane charge transport. Our Al/cr-PVA/Sn/CuPc/Al VOFET operates at low voltages, presents specific transconductance of ∼0.45 S m⁻² and a linear source-drain current on gate voltage dependence.     

具有双绝缘层和修饰电极的薄膜场效应晶体管

研究了具有OTS/SiO2双绝缘层结构及MoO3/Al电极结构的有机薄膜晶体管.器件是以热生长的Si02作为有机薄膜晶体管的栅绝缘层,酞菁铜作为有源层的.OTS/SiO2双绝缘层的结构提高了器件的场效应迁移率和开关电流比,降低了阈值电压.实验表明在同样的栅极电压下,具有MoO3/Al电极的器件和金电极的器件有着相似的源漏输出电流.结果显示具有OTS/SiO2双绝缘层及MoO3/Al电极结构的器件能有效改进有机薄膜晶体管的性能.     

具有双绝缘层和修饰电极的薄膜场效应晶体管

研究了具有OTS/SiO2双绝缘层结构及MoO3/Al电极结构的有机薄膜晶体管.器件是以热生长的Si02作为有机薄膜晶体管的栅绝缘层,酞菁铜作为有源层的.OTS/SiO2双绝缘层的结构提高了器件的场效应迁移率和开关电流比,降低了阈值电压.实验表明在同样的栅极电压下,具有MoO3/Al电极的器件和金电极的器件有着相似的源漏输出电流.结果显示具有OTS/SiO2双绝缘层及MoO3/Al电极结构的器件能有效改进有机薄膜晶体管的性能.     

Organic thin-film field-effect transistors with MoO3/Al electrode and OTS/SiO2 bilayer gate insulator

An organic thin-film transistor (OTFTs) having OTS/SiO₂ bilayer gate insulator and MoO₃/Al electrode configuration between gate insulator and source–drain (S–D) electrodes has been investigated. Thermally grown SiO₂ layer is used as the OTFT gate dielectric and copper phthalocyanine (CuPc) for an active layer. We have found that using silane coupling agents, octadecyltrichlorosilane (OTS) on SiO₂, surface energy of SiO₂ gate dielectric is reduced; consequently, the device performance has been improved significantly. This OTS/SiO₂ bilayer gate insulator configuration increases the field-effect mobility, reduces the threshold voltage and improves the on/off ratios simultaneously. The device with MoO₃/Al electrode has similar source–drain current (I_DS) compared to the device with Au electrode at same gate voltage. Our results indicate that using double-layer of insulator and modified electrode is an effective way to improve OTFT performance.     

Device preparation and characterization of drain current transients in static induction micro transistors

Static induction transistors (SITs) based on copper phthalocyanine (CuPc) were prepared and the dependence of static and transient characteristics on the edge features of the patterned Al gate electrode was studied. Devices having Al gate electrodes deposited with and without a gap between a shadow mask and the substrate were prepared. Devices prepared in the presence of the gap produces a thin transparent edge for the Al gate electrode which enhances the modulation of the drain current by the gate voltage. However, a repetitive slow transient of the drain current was observed for the devices using gap. This transient is considered to be due to the charge carrier trapping at Al dots in the active channel region.     

Humidity sensitive organic field effect transistor

This paper reports the experimental results for the humidity dependent properties of an organic field effect transistor.The organic field effect transistor was fabricated on thoroughly cleaned glass substrate,in which the junction between the metal gate and the organic channel plays the role of gate dielectric.Thin films of organic semiconductor copper phthalocynanine (CuPc) and semitransparent Al were deposited in sequence by vacuum thermal evaporation on the glass substrate with preliminarily deposited Ag source and drain electrodes.The output and transfer characteristics of the fabricated device were performed.The effect of humidity on the drain current,drain current-drain voltage relationship,and threshold voltage was investigated.It was observed that humidity has a strong effect on the characteristics of the organic field effect transistor.     

Humidity sensitive organic field effect transistor

This paper reports the experimental results for humidity dependent properties of organic field effect transistor. The organic field effect transistor was fabricated on thoroughly cleaned glass substrate, in which the junction between metal gate and organic channel plays the role of gate dielectric. The thin films of organic semiconductor copper phthalocynanine (CuPc) and semitransparent Al were deposited in sequence by vacuum thermal evaporation on the glass substrate with preliminary deposited Ag source and drain electrodes. Output and transfer characteristics of the fabricated device were performed. The effect of humidity on the drain current, drain current-drain voltage relationship, and threshold voltage have been investigated. It was observed that humidity has strong effect on the characteristics of organic field effect transistor (OFET).     

Memory effects in hybrid silicon-metallic nanoparticle-organic thin film structures

We report on the electrical behaviour of metal–insulator–semiconductor (MIS) structures fabricated on silicon substrates and using organic thin films as the dielectric layers. These insulating thin films were produced by different methods, including spin-coating (polymethylmethacrylate), thermal evaporation (pentacene) and Langmuir–Blodgett deposition (cadmium arachidate). Gold nanoparticles, deposited at room temperature by chemical self-assembly, were used as charge storage elements. In all cases, the MIS devices containing the nanoparticles exhibited hysteresis in their capacitance versus voltage characteristics, with a memory window depending on the range of the voltage sweep. This hysteresis was attributed to the charging and discharging of the nanoparticles from the gate electrode. A maximum memory window of 2.5 V was achieved by scanning the applied voltage of an Al/pentacene/Au nanoparticle/SiO₂/p-Si structure between 9 and −9 V.     

Effect of the work function of gate electrode on hysteresis characteristics of organic thin-film transistors with Ta2O5/polymer as gate insulator

Organic thin-film transistors (OTFTs) using high dielectric constant material tantalum pentoxide (Ta₂O₅) and benzocyclobutenone (BCBO) derivatives as double-layer insulator were fabricated. Three metals with different work function, including Al (4.3 eV), Cr (4.5 eV) and Au (5.1 eV), were employed as gate electrodes to study the correlation between work function of gate metals and hysteresis characteristics of OTFTs. The devices with low work function metal Al or Cr as gate electrode exhibited high hysteresis (about 2.5 V threshold voltage shift). However, low hysteresis (about 0.7 V threshold voltage shift) OTFTs were attained based on high work function metal Au as gate electrode. The hysteresis characteristics were studied by the repetitive gate voltage sweep of OTFTs, and capacitance–voltage (C–V) and trap loss-voltage (G_p/ω?V) measurements of metal–insulator–semiconductor (MIS) devices. It is proved that the hysteresis characteristics of OTFTs are relative to the electron injection from gate metal to Ta₂O₅ insulator. The electron barrier height between gate metal and Ta₂O₅ is enhanced by using Au as gate electrode, and then the electron injection from gate metal to Ta₂O₅ is reduced. Finally, low hysteresis OTFTs were fabricated using Au as gate electrode.