Novel multiple-selected and multiple-valued memory design using negative differential resistance circuits suitable for standard SiGe-based BiCMOS process

A novel multiple-selected and multiple-valued memory (MSMVM) design using the negative differential resistance (NDR) circuits is demonstrated. The NDR circuits are made of Si-based metal-oxide-semiconductor field-effect-transistor (MOS) and SiGe-based heterojunction bipolar transistor (HBT). During suitably designing the parameters and connecting three MOS–HBT–NDR circuits, we can obtain the three-peak current–voltage (I–V) curves with different peak currents in the combined I–V characteristics. For the traditional resonant-tunneling-diode (RTD) memory circuit, one can only obtain four-valued memory states using a constant current source to bias the three-peak NDR circuit. However in this paper, we utilize two switch-controlled current sources to bias the three-peak NDR circuit at different current levels. By controlling the switches on and off alternatively, we can obtain the four-valued, three-valued, two-valued, and one-valued memory levels under the four different conditions. Our design is based on the standard 0.35 μm SiGe BiCMOS process.     

Logic circuit design using monostable-bistable transition logic element based on standard BiCMOS process

We present a monostable-bistable transition logic element (MOBILE) based on the negative-differential-resistance (NDR) circuit. In particular, this circuit can be completely implemented using the standard BiCMOS process. A traditional MOBILE using two resonant tunneling diodes (RTD) connected in series is a functional logic circuit. The fabrication of RTD is utilized in the complicated molecular-beam-epitaxy (MBE) system. However, we present a MOBILE circuit that is completely made of standard Si-based metal-oxide-semiconductor field effect transistors and SiGe-based heterojunction bipolar transistors. By suitably determining the control voltages and input conditions, we can obtain the operation of the inverter, AND and OR logic gates. We also demonstrate the latch characteristic of this MOBILE circuit. This logic circuit is fabricated using the standard 0.35 μm BiCMOS process without the need for the MBE system.     

SiGe集成电路工艺技术现状及发展趋势

介绍了基于SiGe材料的集成电路工艺技术概况,包括SiGe HBT器件结构、SiGe HBT特色双极工艺、SiGe BiCMOS工艺等。概述了SiGe工艺技术的应用情况以及国内外发展现状,并结合应用需求,提出了国内模拟集成电路制造用SiGe工艺技术的发展趋势。     

Polymer-based non-volatile resistive random-access memory device fabrication with multi-level switching and negative differential resistance state

Resistive random-access memory (RRAM) has been widely considered for its prospective applicability owing to its non-volatile characteristics. In this study, a polymer-based vacuum-free RRAM device fabricated with the conductive polymer, poly(3,4-ethylene-dioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) was proposed. Pristine PEDOT:PSS coated on indium tin oxide (ITO) electrode was used as the active layer, while PEDOT:PSS with 16 vol% ethylene glycol was added for the top electrode. The PEDOT:PSS-based RRAM device demonstrated controlled non-volatile bipolar switching and a good ON/OFF ratio with a negative differential resistance effect in the high-voltage range during the RESET process. Multi-level switching was also accomplished by controlling the voltage, which demonstrated reliable and non-volatile switching. The switching mechanism of this polymer RRAM device can be explained through the electrochemical filamentary formation as well as the current-induced phase segregation of PEDOT:PSS near the anode(ITO)/polymer interface.     

Photo-induced negative differential resistance of organic thin film transistors using anthracene derivatives

We fabricated organic thin film transistors (OTFTs) using soluble 5,5′-(2,6-Bis((4-hexylphenyl)ethynyl)anthracene-9,10-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthieno[3,2-b]thiophene (HTT-ant-THB) as an active layer. We studied the photo-responsive and the gate field-dependent charge transport characteristics of the HTT-ant-THB-based OTFTs. When light (λ_ex = 505 nm) was irradiated on the OTFTs, negative differential resistance (NDR) behavior (i.e., negative slope of the current versus voltage curve) was observed in the reverse bias region of the source-drain current versus voltage characteristics. The NDR effect observed in this study is unique and is controlled by the wavelength and power of the incident light. The current hysteresis and NDR characteristics can be explained in terms of the trapping and releasing mechanism of the mobile charges at the interface between the electrodes and the organic layer. In addition, the NDR effect in the device disappeared on applying negative gate bias.     

DESIGN AND FABRICATION OF Si/SiGe PMOSFETs

Based on theoretical analysis and computer-aided simulation, optimized design prin-ciples for Si/SiGe PMOSFET are given in this paper, which include choice of gate materials, determination of germanium percentage and profile in SiGe channel, optimization of thickness of dioxide and silicon cap layer, and adjustment of threshold voltage.In the light of these principles, a SiGe PMOSFET is designed and fabricated successfully.Measurement indicates that the SiGe PMOSFET‘s(L=2μ同洒45 mS/mm(300K) and 92 mS/mm(77K) ,while that is 33mS/mm (300K) and 39mS/mm (77K) in Si PMOSFET with the same structure.     

用于1.5μmBiCMOS技术的SiGeHBT结构及工艺研究

基于非选择性外延,基极/发射极自对准和集电区选择性注入,提出了一种可用于1.5μmSiGeBiCMOS集成的HBT器件结构及其制作流程。并利用TSuprem4,Medici进行了工艺模拟和电学特性仿真。模拟结果表明,所设计的SiGeHBT具有良好的电学特性。当Vce为2.5V时,其最大电流增益为385,截止频率达到54GHz,验证了流程设计和器件结构的合理性。     

Design and characterization of the negative differential resistance circuits using the CMOS and BiCMOS process

We investigate four novel negative-differential-resistance (NDR) circuits using the combination of the standard Si-based n-channel metal-oxide-semiconductor field-effect-transistor (NMOS) and SiGe-based heterojunction bipolar transistor (HBT). By suitably designing the parameters, we can obtain the Λ- or N-type current–voltage (I–V) curve. Especially, the peak current of the combined I–V curve could be easy adjusted by the external voltage. In application, we utilize the NDR circuit to design an inverter circuit based on the monostable–bistable transition logic element. The fabrication of these NDR circuits and applications could be completely implemented by the simple and standard Si-based CMOS or SiGe-based BiCMOS process without using the complex and expensive process such as metalorganic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).     

SiGe BiCMOS技术发展现状

以通讯领域的需求和技术发展为背景,介绍了SiGe HBT器件以及SiGe BiCMOS技术的发展历程。总结了SiGe HBT器件在器件结构和工艺步骤上的共同点。以IBM公司0.5μmSiGe BiCMOS为例,介绍了SiGe BiCMOS典型工艺步骤,分析了BDG和BAG两种工艺集成方式在不同技术节点上应用的利弊。最后,以捷智半导体和IBM产品线为例,对SiGe HBT器件以及SiGe BiCMOS技术划分技术节点。     

To induce negative differential resistance in organic devices through a ferroelectric polymer

We report how ferroelectric materials induce negative differential resistance (NDR) in organic devices. Fluorescein, which exhibits semiconducting current–voltage characteristics, shows NDR effect in a ferroelectric matrix. Here, we vary the concentration of fluorescein in the ferroelectric matrix to study its effect on NDR. We also show how the degree of polarization controls NDR. We infer that under a suitable bias, the ferroelectric polymer becomes polarized to facilitate electron-injection in the device followed by a double-reduction of fluorescein molecules. From the capacitance–voltage measurements, we substantiate the role of polarization in inducing NDR effect in organic molecules.     

Insight into negative differential resistance in polyphenylene molecular device with graphene electrodes

The organic molecule deposited between gaphene electrodes to form a molecular device has been demonstrated experimentally. Motivated by this case, devices consisting of the polyphenylene molecule bonded covalently with armchair-edged graphene nanoribbon (AGNR) electrodes are constructed and the selective doping with N atom is considered theoretically. Our modeling calculations show that such devices hold the nonlinear and doping-site-dependent transport properties, prominently with multi-peak NDR (negative differential resistance) effect. And, for a peculiar doping site, a very large NDR can be observed, which could be attributed to interactions of the molecular core and doped AGNR electrodes, namely, these hybridized wave functions hold distinctly different delocalization in different benzene rings of the polyphenylene molecule when the applied bias is altered. Also shown is that this large NDR is robust regarding the length increasing and rotation of molecule.     

Electrical bistability,negative differential resistance and carrier transport in flexible organic memory device based on polymer bilayer structure

Bistable nonvolatile memory devices containing two different layers of polymers, viz. MEH-PPV (poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenyl vinylene]) and PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) has been fabricated by a simple spin-coating technique on flexible polyimide (PI) substrates with a structure Al/MEH-PPV/PEDOT:PSS/Ag-Pd/PI. The current–voltage measurements of the as-fabricated devices showed a nonvolatile electrical bistability with electric field induced charge transfer through the polymer layers and negative differential resistance (NDR) which is attributed to the charge trapping in the MEH-PPV layer. The current ON/OFF ratio between the high-conducting state (ON state) and low-conducting state (OFF state) is found to be of the order of 10³ at room temperature which is comparable to organic field effect transistor based memory devices. We propose that such an improvement of rectification ratio (ON/OFF ratio) is caused due to the inclusion of PEDOT:PSS, which serves as a conducting current path for carrier transport; however, NDR is an effect of the trapped charges in the MEH-PPV electron confinement layer. The device shows excellent stability over 10⁴ s without any significant degradation under continuous readout testing in both the ON and OFF states. The carrier transport mechanism of the fabricated organic bistable device has been explained on the basis of different conduction mechanisms such as thermionic emission, space-charge-limited conduction, and Fowler–Nordheim tunneling. A band diagram is proposed to explain the charge transport phenomena. These bilayer structures are free from the drawbacks of the single organic layer based memory devices where the phase separation between the nanoparticles and polymers leads to the degradation of device stability and lifetime.     

Spin negative differential resistance and high spin filtering behavior realized by devices based on graphene nanoribbons and graphitic carbon nitrides

Using nonequilibrium Green’s functions in combination with the density functional theory, we investigate the spin-dependent electronic transport properties of two nanostructure devices based on graphitic carbon nitrides bridging two zigzag graphene nanoribbons, i.e., center and edge bridged devices, respectively. It is found that the center bridged device behaves spin negative differential resistance properties in different bias ranges for the up and down spin current respectively. The edge bridged device presents obvious negative differential resistance only for the down spin current. Moreover, high spin-filtering efficiency over 80% is obtained in the edge bridged device in the bias range of 0–1.0 V. The magnetic properties of these devices suggest promising applications in spintronics and molecular electronics.     

Optimization of SiGe bandgap-based circuits for up to 300 °C operation

An investigation of the performance and reliability issues associated with operating silicon-germanium (SiGe) devices and circuits at temperatures up to 300 °C is presented, along with a new bypass compensation technique for optimizing bandgap reference performance at these extreme temperatures. In addition to the device-level characterization of a SiGe BiCMOS platform, improved circuit design and a device-level collector-substrate leakage suppression technique are shown to improve the viability of SiGe bandgap reference (BGR) circuits on low-cost, bulk Si wafers for high temperature applications. A shunting technique using various transistors to further improve BGR performance above 200 °C is presented, and optimized compensation designs predict new performance records for a bulk-silicon based technology across temperatures from −200 °C to 300 °C. Finally, a closely-related SiGe temperature sensor circuit is characterized for operating environments up to 300 °C.     

基于SiGe BiCMOS 工艺的X 和Ka 波段T / R 多功能芯片设计

提出了应用0. 13 μm SiGe BiCMOS 工艺设计的全集成X 和Ka 波段T/ R 多功能芯片。包括5 位数控 移相器、低噪声放大器、功率放大器和收发控制开关都被集成在单片上。首次将分布式结构应用在多功能芯片的小 信号放大器设计中,而且将堆叠式结构的功放集成在收发芯片中,此两款多功能芯片均有着带宽宽、增益高、输出功 率大等优点。其中X 波段收发芯片接收、发射增益分别达到25 dB、22 dB,发射输出P(-1dB) 达到28 dBm;Ka 波段收发 芯片接收、发射增益分别达到17 dB、14 dB,发射输出P(-1 dB)达到20. 5 dBm。此两款应用硅基工艺设计的多功能芯片 指标均达到国际先进水平,为X 和Ka 波段相控阵系统的小型化和低成本化提供了良好的条件。     

Carbon-doping-induced negative differential resistance in armchair phosphorene nanoribbons

By using a combined method of density functional theory and non-equilibrium Green''s function formalism, we investigate the electronic transport properties of carbon-doped armchair phosphorene nanoribbons (APNRs). The results show that C atom doping can strongly affect the electronic transport properties of the APNR and change it from semiconductor to metal. Meanwhile, obvious negative differential resistance (NDR) behaviors are obtained by tuning the doping position and concentration. In particular, with reducing doping concentration, NDR peak position can enter into mV bias range. These results provide a theoretical support to design the related nanodevice by tuning the doping position and concentration in the APNRs.     

一种宽频压控振荡器及高速双模预分频器的设计与实现

针对射频无线收发机的需求,利用开关电容阵列和多个VOD核的结构设计了一个分段线性超宽频压控振荡器(VCO).采用全电流模逻辑(CML)结构的双模预分频器能满足振荡器最高频率输出的要求.基于IBM 0.35SiGe BiCMOS工艺的流片测试结果表明,电源电压为2.8V时,该压控振荡器的频率能够覆盖2.75～5.73GHz的频段,调频灵敏度约为100MHz/V,在偏离中心频率1MHz处,单边带相位噪声最佳值达到了-120.32 dBc/Hz,预分频器后仿最高工作频率达9.6GHz,两部分核心总工作电流为10mA.     

SiGe SOI CMOS特性分析与优化设计

基于全耗尽SOI CMOS工艺，建立了具有SiGe沟道的SOI MOS器件结构模型，并利用ISE TCAD器件模拟软件，对SiGe SOl CMOS的电学特性进行模拟分析。结果表明，引入SiGe沟道可极大地提高PMOS的驱动电流和跨导（当Ge组分为0．3时，驱动电流提高39．3％，跨导提高38．4％），CMOS电路的速度显著提高；在一定的Ge总量下，改变Ge的分布，当沟道区呈正向递减式分布时，电路速度最快。     

Trimming process and temperature variation in second-order bandgap voltage reference circuits

This paper presents the design and experimental performance of a second-order bandgap voltage reference integrated circuit (IC). Experimentally observed nominal reference voltage at room temperature is 1.150 V with best temperature performance of 3 mV variation over −40 to 120 °C. A 5-bit resistor trimming is used to compensate the variation of reference voltage due to layout mismatch and process variation. A trimming methodology is described in this paper to optimize both the temperature performance and reduce the variation of the room temperature voltage over different samples. Even with best temperature performance trim-code, the absolute variation in reference voltage over 20 samples is 85 mV which is trimmed to ±11 mV (1.3%) using the proposed trimming methodology. The second-order bandgap circuit is designed in a 0.5 μm BiCMOS process with less than 50 μA current consumption.     

Fabrication and application of MOS-HBT-NDR circuit using standard SiGe process

A novel negative differential resistance (NDR) circuit made of a metal-oxide-semiconductor field-effect-transistor (MOS) and a heterojunction bipolar transistor (HBT) is presented. By suitably modulating the width/length parameters of the MOS devices, the fabrication of this MOS-HBT-NDR circuit and its application to inverter design based on the standard 0.35 mum SiGe process was demonstrated