A 680 V LDMOS on a thin SOI with an improved field oxide structure and dual field plate

A 680 V LDMOS on a thin SOI with an improved field oxide（FOX） and dual field plate was studied experimentally.The FOX structure was formed by an ＂oxidation-etch-oxidation＂ process,which took much less time to form,and had a low protrusion profile.A polysilicon field plate extended to the FOX and a long metal field plate was used to improve the specific on-resistance.An optimized drift region implant for linear-gradient doping was adopted to achieve a uniform lateral electric field.Using a SimBond SOI wafer with a 1.5μm top silicon and a 3μm buried oxide layer,CMOS compatible SOI LDMOS processes are designed and implemented successfully. The off-state breakdown voltage reached 680 V,and the specific on-resistance was 8.2Ω·mm^2.

Nitrogen mobility,ammonia volatilization,and estimated leaching loss from long-term manure incorporation in red soil

Nitrogen（N） loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil（Ferralic Cambisol） after 19 years of mineral（synthetic） and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined： control（CK）, chemical nitrogen and potash fertilizer（NK）, chemical nitrogen and phosphorus fertilizer（NP）, chemical nitrogen, phosphorus and potash fertilizer（NPK） and the NPK with manure（NPKM, 70% N from manure）. Based on the soil total N storage change in 0–100 cm depth, ammonia（NH_3） volatilization, nitrous oxide（N_2O） emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments（NK, NP and NPK） showed increased nitrate（NO_3~–） concentration with increasing soil depth, indicating higher leaching potential. However, total NH_3 volatilization loss was much higher in the NPKM（19.7%） than other mineral fertilizer treatments（≤4.2%）. The N_2O emissions were generally low（0.2–0.9%, the highest from the NPKM）. Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH_3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporationis an essential strategy in N fertilization management in upland red soil cropping system.

Recovery of PMOSFET NBTI under different conditions

Negative bias temperature instability（NBTI） has become a serious reliability issue, and the interface traps and oxide charges play an important role in the degradation process. In this paper, we study the recovery of NBTI systemically under different conditions in the P-type metal–oxide–semiconductor field effect transistor（PMOSFET）, explain the various recovery phenomena, and find the possible processes of the recovery.

Investigation of gate current in nano-scale MOSFETs by Monte Carlo solution of quantum Boltzmann equation

This paper investigates gate current through ultra-thin gate oxide of nano-scale metal oxide semiconductor field effect transistors （MOSFETs）, using two-dimensional （2D） full-band self-consistent ensemble Montc Carlo method based on solving quantum Boltzmann equation. Direct tunnelling, Fowler-Nordheim tunnelling and thermionic emission currents have been taken into account for the calculation of total gate current. The 2D effect on the gate current is investigated by including the details of the energy distribution for electron tunnelling through the barrier. In order to investigate the properties of nano scale MOSFETs, it is necessary to simulate gate tunnelling current in 2D including non-equilibrium transport.

Model of hot-carrier induced degradation in ultra-deep sub-micrometer nMOSFET

The degradation produced by hot carrier （HC） in ultra-deep sub-micron n-channel metal oxide semiconductor field effect transistor （nMOSFET） has been analyzed in this paper. The generation of negatively charged interface states is the predominant mechanism for the ultra-deep sub-micron nMOSFET. According to our lifetime model of p-channel MOFET （pMOFET） that was reported in a previous publication, a lifetime prediction model for nMOSFET is presented and the parameters in the model are extracted. For the first time, the lifetime models of nMOFET and pMOSFET are unified. In addition, the model can precisely predict the lifetime of the ultra-deep sub-micron nMOSFET and pMOSFET.

Ultra-Low Power 1 Volt Small Size 2.4 GHz CMOS RF Transceiver Design for Wireless Sensor Node

Ultra-low power transceiver design is proposed for wireless sensor node used in the wireless sensor network（WSN）.Typically,each sensor node contains a transceiver so it is required that both hardware and software designs of WSN node must take care of energy consumption during all modes of operation including active/sleep modes so that the operational life of each node can be increased in order to increase the lifetime of network.The current declared size of the wireless sensor node is of millimeter order,excluding the power source and crystal oscillator.We have proposed a new 2.4 GHz transceiver that has five blocks namely XO,PLL,PA,LNA and IF.The proposed transceiver incorporates less number of low-drop outs（LDOs）regulators.The size of the transceiver is reduced by decreasing the area of beneficiary components up to 0.41 mm;of core area in such a way that some functions are optimally distributed among other components.The proposed design is smaller in size and consumes less power,<1 mW,compared to other transceivers.The operating voltage has also been reduced to 1 V.This transceiver is most efficient and will be fruitful for the wireless networks as it has been designed by considering modern requirements.

Tungsten oxide nanostructures:controllable growth and field emission

Non-fully oxidized tungsten oxide（WO_（3-x）） nanostructures with controllable morphology were fabricated by adjusting the gas pressure in chemical vapor deposition.The comparative field emission（FE） measurements showed that the obtained W_（18）O_（49） nanowires have excellent FE property.The turn-on field was 7.1 V/μm for 10μA/cm^2 and the observed highest current density was 4.05 mA/cm^2 at a field of 17.2 V/μm.Good electron emission reproducibility was also observed during thermal evaporation and desorption testing.

Heat transfer enhancement in MOSFET mounted on different FR4 substrates by thermal transient measurement

Miniaturization of electronic package leads to high heat density and heat accumulation in electronics device, resulting in short life time and premature failure of the device. Junction temperature and thermal resistance are the critical parameters that determine the thermal management and reliability in electronics cooling. Metal oxide field effect transistor（MOSFET）is an important semiconductor device for light emitting diode-integrated circuit（LED IC） driver application, and thermal management in MOSFET is a major challenge. In this study, investigations on thermal performance of MOSFET are performed for evaluating the junction temperature and thermal resistance. Suitable modifications in FR4 substrates are proposed by introducing thermal vias and copper layer coating to improve the thermal performance of MOSFET. Experiments are conducted using thermal transient tester（T3ster） at 2.0 A input current and ambient temperature varying from25℃ to 75℃. The thermal parameters are measured for three proposed designs： FR4 with circular thermal vias, FR4 with single strip of copper layer and embedded vias, and FR4 with I-shaped copper layer, and compared with that of plain FR4 substrate. From the experimental results, FR4I-shaped shows promising results by 33.71% reduction in junction temperature and 54.19% reduction in thermal resistance. For elevated temperature, the relative increases in junction temperature and thermal resistance are lower for FR4I-shaped than those for other substrates considered. The introduction of thermal vias and copper layer plays a significant role in thermal performance.

Weakly magnetic field-assisted synthesis of magnetite nano-particles in oxidative co-precipitation

This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite （Fe3O4） nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction. The XRD results show that a weakly magnetic induction below 220 Gs could accelerate the phase transformation from goethite （α-FeOOH） to magnetite （Fe3O4）, and affect the crystal structure, the particle size/morphology and magnetic response of the magnetite nano-particles synthesized. In addition, a higher concentration of the FeCl2 solution in the synthesis reaction led to finer particles, both with and without magnetic induction.

Ultimate dielectric scaling of 2D transistors via van der Waals metal integration

The two-dimensional transition metal dichalcogenides(TMDs)have attracted intense interest as an atomically thin semiconductor channel for the continued transistor scaling.However,with a dangling bond free surface,it has been a key challenge to reliably integrate high-quality gate dielectrics on TMDs.In particular,the atomic layer deposition of dielectrics on TMDs typically features highly non-uniform nucleation and produces a highly rough or porous dielectric film with rich pinholes that are prone to further damage during the gate integration process.Herein we report a van der Waals(vdW)integration route towards highly reliable gate metal integration on porous dielectrics.The physical lamination process employed by the vdW integration avoids the direct deposition of metal electrodes into porous dielectrics to ensure reliable gate integration and produce low gate leakage devices.The electrical measurements demonstrate the vdW integrated MoS_(2) top gate devices exhibit substantially reduced gate leakage current that is about 3-5 orders of magnitude smaller than that with deposited metal electrodes.Furthermore,we show the vdW integration process can be used to create high performance top-gated MoS_(2) transistors with ultrathin Al_(2)O_(3) dielectrics down to 1 nm,representing the ultimate dielectric scaling for TMDs transistors.This study demonstrates that vdW integration can enable highly reliable gate integration on relatively low quality dielectrics on TMDs,and opens an interesting pathway to high-performance top-gate transistors using dangling bond free two-dimensional(2D)semiconductors.

Full scale amendment of a contaminated wood impregnation site with iron water treatment residues

Iron water treatment residues （Fe-WTR） are a free by-product of the treatment of drinking water with high concentration of iron oxides and potential for arsenic sorption. This paper aims at applying Fe- WTR to a contaminated site, measuring the reduction in contaminant leaching, and discussing the design of delivery and mixing strategy for soil stabilization at field scale and present a cost-effective method of soil mixing by connnon contractor machinery. Soil contaminated by As, Cr, and Cu at an abandoned wood impregnation site was amended with 0.22% （dw） Fe-WTR. To evaluate the full scale amendment a 100 mtest site and a control site （without amendment） were monitored for 14 months. Also soil analysis of Fe to evaluate the degree of soil and Fe-WTR mixing was done. Stabilization with Fe-WTR had a significant effect on leachable contaminants, reducing pore water As by 93%, Cu by 91% and Cr by 95% in the upper samplers. Dosage and mixing of Fe-WTR in the soil proved to be difficult in the deeper part of the field, and Pire water concentrations of arsenic was generally higher.Despite water logged conditions no increase in dissolved iron or arsenic was observed in the amended soil. Our field scale amendment of contaminated soil was overall successful in decreasing leaching of As, Cr and Cu. With minor improvements in the mixing and delivery strategy, this stabilization method is suggested for use in cases, where leaching ofCu, Cr and As constitutes a risk for groundwater and freshwater.