Effects of self-heating on planar heterostructure barrier varactordiodes

The conversion efficiency for planar Al_0.7GaAs-GaAs heterostructure barrier varactor triplers is shown to be reduced from a theoretical efficiency of 10% to 3% due to self-heating. The reduction is in accordance with measurements on planar Al_0.7GaAs-GaAs heterostructure barrier varactor (HBV) triplers to 261 GHz at room temperature and with low temperature tripler measurements to 255 GHz. The delivered maximum output power at 261 GHz is 2.0 mW. Future HBV designs should carefully consider and reduce the device thermal resistance and parasitic series resistance. Optimization of the RF circuit for a 10 μm diameter device yielded a delivered output power of 3.6 mW (2.5% conversion efficiency) at 234 GHz     

Impact of collector-base junction traps on low-frequency noise in high breakdown Voltage SiGe HBTs

This work investigates the impact of collector-base (CB) junction traps on low-frequency noise in high breakdown voltage (HBV) SiGe HBTs. By comparing the base current and 1/f noise at the same internal emitter-base (EB) voltage of the standard breakdown voltage (SBV) and HBV devices, we show that the CB junction traps not only increase base current, but also contribute base current 1/f noise when high injection occurs. The individual 1/f noise contributions from the emitter-base junction traps and from the collector-base junction traps are separated. The dependence of the 1/f noise component on the corresponding base current component is determined, and shown to be different for the EB and CB junction traps. The dependence of the total 1/f noise on the total base current, however, remains the same before and after high injection occurs in the HBV device, which is approximately the same as that for the SBV device. The I/sub B/ contribution from the CB junction recombination current needs to be modeled for accurate I-V and 1/f noise modeling.     

Planar multibarrier 80/240-GHz heterostructure barrier varactortriplers

Prototype planar four barrier GaAs/Al_0.7Ga_0.3As heterostructure barrier varactors (HBV's) for frequency tripling from 80 to 240 GHz have been fabricated using a process in which the device surface channel is etched prior to the formation of the contact pad-to-anode air-bridge finger. Formation of the device air-bridge finger after etching the surface channel is facilitated by a trench planarization technique and yields a device with minimal parasitic capacitances. Planar four-barrier HBV triplers with nominal 10-μm diameter anodes have been tested in a crossed-waveguide tripler block; as much as 2 mW of power has been generated at 252 GHz with a flange to-flange tripling efficiency of 25%. These devices are the first planar or multibarrier HBV triplers reported and their output powers are nearly double that of previous whisker-contacted single-barrier HBVs     

Fabrication and performance of InP-based heterostructure barriervaractors in a 250-GHz waveguide tripler

High-performance InGaAs-InAlAs-AlAs heterostructure barrier varactors (HBV's) have been designed, fabricated, and RF tested in a 250-GHz tripler block. The devices with two barriers stacked on the same epitaxy are planar integrated with coaxial-, coplanar-, and strip-type configurations. They exhibit state-of-the-art capacitance voltage characteristics with a zero-bias capacitance C₃⁰ of 1 fF/μm² and a capacitance ratio of 6:1. Experiments in a waveguide tripler mount show a 9.8-dBm (9.55-mW) output power for 10.7% conversion efficiency at 247.5 GHz. This is the highest output power and efficiency reported from an HBV device at J-band (220-325 GHz)     

Frequency multiplier measurements on heterostructure barriervaractors on a copper substrate

We have fabricated heterostructure barrier varactors (HBV) on a copper substrate, which offers reduced spreading resistance, and improved thermal conductivity compared to an InP substrate. The devices are fabricated without degrading the electrical characteristics. The three-barrier HBV material grown by MOVPE has a leakage current of only 0.1 μA/μm² at 19 V. The maximum capacitance is 0.54 fF/μm². In a frequency tripler experiment a maximum output power of 7.1 mW was generated at 221 GHz with a flange-to-flange efficiency of 7.9%     

11% efficiency 100 GHz InP-based heterostructure barrier varactor quintupler

A record conversion efficiency of 11.4% at 100 GHz using a heterostructure barrier varactor (HBV) quintupler is demonstrated. The quintupler is based on a microstrip circuit mounted in a full-height crossed-waveguide block. The nonlinear element consists of a planar HBV diode fabricated in InGaAs/InAlAs/AlAs epitaxial layers on an InP substrate     

Magnetic-Activated Nanosystem with Liver-Specific CRISPR Nonviral Vector to Achieve Spatiotemporal Liver Genome Editing as Hepatitis B Therapeutics

Chronic hepatitis B infection remains incurable due to the stable presence of various forms of hepatitis B virus (HBV) genome, especially the HBV covalently closed circular DNA (cccDNA). The emergence of clustered regularly interspaced short palindromic repeat (CRISPR) technology provides a new opportunity to potentially cure the HBV infection. However, the efficiency and specificity remain unsatisfactory, especially for nonviral CRISPR/Cas9 delivery. To tackle these, a liver-specific CRISPR/Cas9 magnetic nanosystem FMNP_pAG333/sgXPP is constructed based on fluorinated polyethylenimine-coated magnetic nanoparticles and liver-specific ApoE.HCR.hAAT promoter-driven Cas9-T2A-EGFP plasmid with dual sgRNAs. The elaborate system enables magnetic field-induced spatially specific distribution and hepatocyte-specific promoter-driven liver-specific gene editing. Moreover, this CRISPR/Cas9 magnetic nanosystem is designed to disrupt the two conserved sites in X opening reading frame and Pol opening reading frame of the HBV genome, thereby significantly inactivating the HBV genome without showing off-target effects. Treatment with FMNP_pAG333/sgXPP for 7 days reduces serum HBsAg levels by 76% with a total editing efficiency of ≈20% in the two conserved sites. Collectively, this study demonstrates spatiotemporal liver genome editing as well as the feasibility of applying a nonviral CRISPR/Cas9 vector for HBV treatment, which may open up a new application for CRISPR therapeutics.     

Performance of High-Reliability and High-Linearity InGaP/GaAs HBT PAs for Wireless Communication

An InGaP heterojunction-bipolar-transistor (HBT) power amplifier with the best linearity and high reliability is presented in this paper for use in wireless digital mobile communication systems. We optimized the linearity of a novel HBT device and investigated its reliability. Using SILVACO software, we performed a simulation of the HBT device. The best linearity, which was revealed for the device with a capacitance ratio C_bc (0/6 V), is 1.25 at a BV_ceo of 22 V. After the device was fabricated, a reasonably high PAE, i.e., ~ 55%, was obtained at 2.0 GHz, and an adjacent channel power ratio of over -48 dBc was achieved. In the reliability testing, the device, which was stressed at V_ce = 3 V and J_C = 25 kA/cm² under 85°C ambient temperature and 85% humidity, showed no failure for more than 1100 h. No significant beta degradation was observed under an extreme current J_C = 200 kA/cm² stress under wafer-level electrical/thermal overstress tests.     

Pivotal factors in solution-processed,non-fullerene,all small-molecule organic solar cell device optimization

The importance of device structure and active-layer processing when screening non-fullerene acceptors was demonstrated through the organic solar cell device performance optimization of a solution processable non-fullerene, all small-molecule bulk heterojunction (BHJ) blend. Key tuning parameters were identified; notably, the largest improvement in performance was achieved by switching from the conventional device architecture (ITO/PEDOT:PSS/D-A BHJ/Ca/Al) to an inverted structure (ITO/ZnO/D-A BHJ/MoOx/Ag), approximately doubling the power conversion efficiency from best cells of 0.5%–1.0%, demonstrating the importance of investigating more than a single architecture when screening novel non-fullerene acceptors.     

基于BP神经网络的肝癌放疗致乙型肝炎病毒再激活分类预测模型

研究针对原发性肝癌（ primary liver carcinoma， PLC）患者精确放疗后乙型肝炎病毒（ Hepatitis B virus， HBV）再激活分类预测模型，采用logistic提取关键特征子集，发现外放边界、肿瘤分期TNM和HBV DNA水平是HBV再激活的危险因素（ P ＜0．05）。建立BP神经网络分类预测模型，对原发性肝癌初始数据集和关键特征子集进行HBV再激活分类预测。实验结果表明，BP 网络对HBV再激活有着良好的分类预测性能，分类预测准确性从73．33％提高到78．89％，关键特征子集分类预测准确性高于初始数据集分类预测准确性，表明了特征提取后的关键特征子集具有优秀的类别区分性。     

Accurate current sensor for lateral IGBT smart power integration

This paper describes research work on the design and fabrication of a current sensor suitable for smart power integration in lateral insulated-gate bipolar transistor (LIGBT) structure. In general, the proposed design can also be used for various types of MOS-controlled bipolar transistor structures. Both the electron and hole current sensor layers are integrated in a concise form within the device structure. The sensing performance was further refined with the proposed flat-top doping profile achievable through a double-implantation, single-anneal and post-anneal-oxidation approach. The integrated structure was fabricated on silicon wafer with laboratory measurements performed to verify its electrical performance. The sensing ratio is maintained at a relatively constant level with a variation of within /spl plusmn/0.46% and /spl plusmn/1.2% (as a switching device), and /spl plusmn/0.85% and /spl plusmn/1.73% (as an amplifier device), respectively, when anode current and gate voltage vary. For operating temperature range of 300 K to 400 K, the sensor is able to maintain a sensing ratio within /spl plusmn/5.2% variation.     

Design of Dual-Junction Three-Terminal CdTe/InGaAs Solar Cells

In this paper we report the modeling-based design of a CdTe (1.5 eV) on InGaAs (0.74 eV) dual-junction three-terminal solar cell. The device was optimized for thickness of active layers and for doping levels. Efficiency of 26.6% was predicted for the tandem photovoltaic (PV) device under standard testing conditions (STC). We investigated tandem PV device performance at different temperatures and found the device had a total efficiency temperature coefficient of approximately ?0.15%/°C. We also investigated device suitability for concentrated photovoltaic (CPV) applications in addition to its conventional PV applications. The device proved a good candidate for CPV applications under 1000 suns.     

Monolithic coplanar transmission lines loaded by heterostructurebarrier varactors for a 60 GHz tripler

Nonlinear transmission lines (NLTLs) loaded by InP-based heterostructure barrier varactors (HBVs) have been fabricated in a monolithic coplanar technology for the first time. The devices were designed for a tripler with a 60 GHz; output frequency. The single HBV diodes, fabricated in a dual barrier scheme, exhibit a capacitance ratio of 6:1, a normalized capacitance of 1.4 fF/μm² and a voltage breakdown in excess of 10 V. Under moderate pumping (20 dBm), a tripling operation with 30% bandwidth was demonstrated with unsaturated conversion efficiency (1%) for a eight-HBV prototype     

蓝宝石衬底上槽栅型X波段增强型AlGaN/GaN HEMT

研制了一款X波段增强型AlGaN/GaN高电子迁移率晶体管(HEMT)。在3英寸(1英寸=2.54 cm)蓝宝石衬底上采用低损伤栅凹槽刻蚀技术制备了栅长为0.3μm的增强型AlGaN/GaN HEMT。所制备的增强型器件的阈值电压为0.42 V,最大跨导为401 mS/mm,导通电阻为2.7Ω·mm。器件的电流增益截止频率和最高振荡频率分别为36.1和65.2 GHz。在10 GHz下进行微波测试,增强型AlGaN/GaN HEMT的最大输出功率密度达到5.76 W/mm,最大功率附加效率为49.1%。在同一材料上制备的耗尽型器件最大输出功率密度和最大功率附加效率分别为6.16 W/mm和50.2%。增强型器件的射频特性可与在同一晶圆上制备的耗尽型器件相比拟。     

利用CsN3n型掺杂电子传输层改善OLED器件性能的研究

为了能够有效地提高电子的注入和传输能力,改善有机电致发光器件的性能,本文利用CsN₃作为n型掺杂剂,对有机电子传输材料Bphen进行n型电学掺杂,制备了结构为ITO/MoO₃（2 nm）/NPB（50 nm）/Alq₃（30 nm）/Bphen（15 nm）/Bphen：CsN₃（15 nm,x%,x=10,15,20）/Al（100 nm）的器件。实验结果表明,CsN₃是一种有效的n型掺杂剂,以掺杂层Bphen：CsN₃ 作为电子传输层,可以有效地降低电子的注入势垒,改善器件的电子注入和传输能力,从而降低器件的开启电压,同时提高了器件的亮度和发光效率。在掺杂浓度为10%时器件的性能最优,开启电压仅为2.3 V,在7.2 V的驱动电压下,达到最大亮度29 060 cd/m²,是非掺杂器件的2.5倍以上。当驱动电压为6.6 V时,达到最大电流效率3.27 cd/A。而当掺杂浓度进一步提高时,由于Cs扩散严重,发光区形成淬灭中心,造成器件的效率下降。     

High-mobility GeSi PMOS on SIMOX

A new p-channel GeSi-SIMOX device is presented. The device consists of a Si/Ge_0.3Si_0.7/Si channel, which is grown pseudomorphically on a SIMOX substrate. Due to reduced vertical electric field and band bending at the surface of a GeSi-SIMOX device, hole confinement in the buried channel is improved over that of a GeSi-bulk device. Experimentally, the effective channel mobility of this device is found to be 90% higher than that of an identically processed conventional SIMOX device     

Simulation Study of High-Performance Modified Saddle MOSFET for Sub-50-nm DRAM Cell Transistors

A novel modified saddle MOSFET to be applied to sub-50-nm DRAM technology with high performance and easy scalability is proposed, and its characteristics at a given recess open width of 40 nm is studied by device simulation. The proposed device has$sim$21% lower gate capacitance and lower$I_ off$by two orders of magnitude than a conventional saddle device under nearly the same$I_ on$. In addition, the proposed device showed less threshold voltage sensitivity to the corner shape and lower gate delay time$(CV/I)$by$sim$30% than the conventional recess channel device while keeping nearly the same$I_ off$.     

Novel compact polarization converters based on ultra short bends

A novel integrated polarization converter based on ultra short bends is presented, which has a potential for low loss and small device size. A conversion value of 85% was experimentally measured with excess loss of 2.7 dB and overall dimensions of 975/spl times/83 /spl mu/m. Also 45% conversion was measured with extremely low excess loss of 0.4 dB for a device size of 760/spl times/86 /spl mu/m.     

浮栅器件栅耦合系数修正的探讨

提取浮栅器件栅耦合率的方法一般都是针对不可忽略的沟道耦合现象进行修正.对这些方法进行了比较、分析发现,对于短沟道浮栅器件,会由于参考器件存在明显的DIBL/SIBL效应,使提取的源、漏耦合系数偏大产生了很大的误差.提出了一种对亚阈值斜率法提取浮栅器件栅耦合系数的修正方法,结合了DIBL/SIBL效应因子,基于亚阈值斜率之比来较简单地实现更精确的近似,得到的栅耦合系数与设计值吻合较好,误差在2%以内,表明此修正法是合理且精确的.     

Power and linearity characteristics of GaN MISFETs on sapphire substrate

The improvement of device performance arising from the adoption of a MIS gate structure in GaN field-effect transistor (FET) is presented. GaN MISFET/MESFET devices were fabricated on sapphire substrate with and without the insertion of a thin SiN layer on device surface. The MISFET device showed improved device characteristic due to significant reduction in device gate leakage with respect to the standard MESFET structure. Measured power and linearity performance showed promising results. Under single-tone testing at 4 GHz, device yielded saturated output power 6.2 W/mm with 55% peak power added efficiency. When tested with two-tone signal device maintained a carrier to third order intermodulation ratio of 30 dBc up to power levels of 1.8 W/mm with 40% power added efficiency.