Parasitic source resistance at different temperatures for AlGaN/AlN/GaN heterostructure field-effect transistors

The parasitic source resistance（RS） of AlGaN/AlN/GaN heterostructure field-effect transistors（HFETs） is studied in the temperature range 300–500 K. By using the measured RSand both capacitance–voltage（C–V） and current–voltage（I–V） characteristics for the fabricated device at 300, 350, 400, 450, and 500 K, it is found that the polarization Coulomb field（PCF） scattering exhibits a significant impact on RSat the above-mentioned different temperatures. Furthermore, in the AlGaN/AlN/GaN HFETs, the interaction between the additional positive polarization charges underneath the gate contact and the additional negative polarization charges near the source Ohmic contact, which is related to the PCF scattering, is verified during the variable-temperature study of RS.

A novel diode string triggered gated-Pi N junction device for electrostatic discharge protection in 65-nm CMOS technology

A novel diode string-triggered gated-Pi N junction device, which is fabricated in a standard 65-nm complementary metal-oxide semiconductor（CMOS） technology, is proposed in this paper. An embedded gated-Pi N junction structure is employed to reduce the diode string leakage current to 13 n A/μm in a temperature range from 25°C to 85°C. To provide the effective electrostatic discharge（ESD） protection in multi-voltage power supply, the triggering voltage of the novel device can be adjusted through redistributing parasitic resistance instead of changing the stacked diode number.

FinFET Performance Enhancement by Source/Drain Cavity Structure Optimization

Fin field-effect transistor(FinFET)technology has been introduced to the mainstream complementary metal-oxide semiconductor(CMOS)manufacturing for low-power and highperformance applications.However,advanced FinFET nodes are facing significant challenges to enhance the device performance due to the increasingly prominent parasitic resistance and capacitance.In this study,for the first time,we demonstrate methods of enhancing p-channel FinFET(pFET)performance on a fully integrated advanced FinFET platform via source/drain(S/D)cavity structure optimization.By modulating the cavity depth and proximity around the optimal reference point,we show that the trade-off between the S/D resistance and short channel effect,as well as the impact on the parasitic capacitance must be considered for the S/D cavity structure optimization.An extra process knob of applying cavity implant on the desired cavity structure was also demonstrated to modify the S/D junction profile for device performance enhancement.

Accurate capacitance-voltage characterization of organic thin films with current injection

To deal with the invalidation of commonly employed series model and parallel model in capacitance-voltage(C-V)characterization of organic thin films when current injection is significant,a three-element equivalent circuit model is proposed.On this basis,the expression of real capacitance in consideration of current injection is theoretically derived by small-signal analysis method.The validity of the proposed equivalent circuit and theoretical expression are verified by a simulating circuit consisting of a capacitor,a diode,and a resistor.Moreover,the accurate C-V characteristic of an organic thin film device is obtained via theoretical correction of the experimental measuring result,and the real capacitance is 35.7%higher than the directly measured capacitance at 5-V bias in the parallel mode.This work strongly demonstrates the necessity to consider current injection in C-V measurement and provides a strategy for accurate C-V characterization experimentally.

Impact of parasitic resistance on the ESD robustness of high-voltage devices

The impacts ofsubstrate parasitic resistance and drain ballast resistance on electrostatic discharge （ESD） robustness of LDMOS are analyzed. By increasing the two parasitic resistances, the ESD robustness of LDMOS are significantly improved. The proposed structures have been successfully verified in a 0.35μm BCD process without using additional process steps. Experimental results show that the second breakdown current of the optimal structure increases to 3,5 A, which is about 367% of the original device.

A minimum-order boundary element method to extract the 3-D inductance and resistance of the interconnects in VLSI

The high frequency resistance and inductance of the 3-D complex interconnect structures can be calculated by solving an eddy current electromagnetic problem. In this paper, a model for charactering such a 3-D eddy current problem is proposed, in which the electromagnetic fields in both the conducting and non-conducting regions are described in terms of the magnetic vector potential, and a set of the indirect boundary integral equations (IBIE) is obtained. The IBIEs can be solved by boundary element method, so this method avoids discretizing the domain of the conductors. As an indirect boundary element method, it is of minimum order. It does not restrict the direction of the current in conductors, and hence it can consider the mutual impedance between two perpendicular conductors. The numerical results can well meet the analytical solution of a 2-D problem. The mutual impedance of two perpendicular conductors is also shown under the different gaps between conductors and different frequencies.

Potato aphid Macrosiphum euphorbiae performance is determined by aphid genotype and not mycorrhizal fungi or water availability

Intra- and interspecific variation in plant and insect traits can alter the strength and direction of insect-plant interactions, with outcomes modified by soil biotic and abiotic conditions. We used the potato aphid （Macrosiphum euphorbiae Thomas） feeding on cultivated Solanum tuberosum and wild Solanurn berthaulti to study the impact of water availability and plant mutualistic arbuscular mycorrhizal （AM） fungi on aphid performance and susceptibility to a parasitoid wasp （Aphidius ervi Haliday）. Plants were grown under glass with live or sterile AM fungal spores and supplied with sufficient or reduced water supply. Plants were infested with 1 of 3 genotypes ofM. euphorbiae or maintained as aphidfree controls; aphid abundance was scored after 1 week, after which aphid susceptibility to A. ervi was assayed explanta. Solarium tuberosum accumulated c. 20% more dry mass than S. berthaultii, and root mass of S. berthaultii was smallest under reduced water supply in the presence of AM fungi. Aphid abundance was lowest on S. berthaultii and highest for genotype ＂2＂ aphids; genotype ＂1＂ aphid density was particularly reduced on S. berthaultii. Aphid genotype ＂1＂ exhibited low susceptibility to parasitism and was attacked less frequently than the other two more susceptible aphid genotypes. Neither AM fungi nor water availability affected insect performance. Our study suggests a fitness trade-offin M. euphorbiae between parasitism resistance and aphid performance on poor quality Solarium hosts that warrants further exploration, and indicates the importance of accounting for genotype identity in determining the outcome of multitrophic interactions.

Coinfection of the secondary symbionts,Hamiltonella defensa and Arsenophonus sp.contribute to the performance of the major aphid pest,Aphis gossypii(Hemiptera:Aphididae)

Bacterial endosymbionts play important roles in ecological traits of aphids.In this study,we characterize the bacterial endosymbionts of A.gossypii collected in Karaj,Iran and their role in the performance of the aphid.Our results indicated that beside Buchnera aphidicola,A.gossypii,also harbors both Hamiltonella defensa and Arsenophonus sp.Quantitative PCR(qPCR)results revealed that the populations of the endosymbionts increased throughout nymphal development up to adult emergence;thereafter,populations of Buchnera and Arsenophonus were diminished while the density of H.defensa constantly increased.Buchnera reduction caused prolonged development and no progeny production.Furthermore,secondary symbiont reduction led to reduction of the total life span and intrinsic rate of natural increase as well as appearance of the deformed dead offspring in comparison with the control insects.Reduction of the secondary symbionts did not affect parasitism rate of the aphid by the parasitic wasp Aphidius matricariae.Together these findings showed that H.defensa and Arsenophonus contributed to the fitness of A.gossypii by enhancing its performance,but not through parasitoid resistance.

Prospects of a β-SiC based IMPATT oscillator for application in THz communication and growth of aβ-SiC p-n junction on a Ge modified Si〈100〉substrate to realize THz IMPATTs

The prospects ofa p＋nn＋ cubic silicon carbide （3C-SiC/fl-SiC） based IMPATT diode as a potential solidstate terahertz source is studied for the first time through a modified generalized simulation scheme. The simulation predicts that the device is capable of generating an RF power output of 63.0 W at 0.33 THz with an efficiency of 13%. The effects of parasitic series resistance on the device performance and exploitable RF power level are further simulated. The studies clearly establish the potential of 3C-SiC as a base semiconductor material for a high-power THz IMPATT device. Based on the simulation results, an attempt has been made to fabricate β-SiC based IMPATT devices in the THz region. Single crystalline, epitaxial 3C-SiC films are deposited on silicon （Si） （100） substrates by rapid thermal chemical vapour deposition （RTPCVD） at a temperature as low as 800 ℃ using a single precursor methylsilane, which contains Si and C atoms in the same molecule. No initial surface carbonization step is required in this method. A p-n junction with an n-type doping concentration of 4 × 10^24 m-3 （which is similar to the simulated design data） has been grown successfully and the characterization of the grown 3C-SiC film is reported in this paper. It is found that the inclusion of Ge improves the crystal quality and reduces the surface roughness.