Pumping Technique Research Articles

Comprehensive study of hole injection in non-overlapped implantation n-type MOSFETs

The promising use of non-overlapped implantation (NOI) n-type MOSFETs as nonvolatile memory (NVM) devices has received considerable interest owing to their simple device structure and compatibility with logic CMOS processing. In NOI n-type MOSFETs, the charge distribution by channel hot electron injection (CHEI) programming markedly differs from that in other charge trapping devices in terms of electron injection distribution. In this study, hot hole injection (HHI) in NOI NVM devices is investigated using Technology Computer Aided Design (TCAD) simulations, measured program/erase speeds, and charge pumping (CP) techniques. Furthermore, HHI efficiency is theoretically deduced and compared with that of silicon–oxide–nitride–oxide–silicon (SONOS) devices. Similar to the results for SONOS device, the lateral fields by VD biases significantly enhance HHI for erasing NOI devices. However, preprogrammed electrons are also dominant in erasing NOI devices. On the basis of the CP results, the hole distribution by HHI in NOI NVM devices strongly correlates with the distribution of preprogrammed electrons.

Proton Damage Comparison of an e2v Technologies n-channel and p-channel CCD204

Comparisons have been made of the relative degradation of charge transfer efficiency in n-channel and p-channel CCDs subjected to proton irradiation. The comparison described in this paper was made using e2v technologies plc. CCD204 devices fabricated using the same mask set. The device performance was compared over a range of temperatures using the same experimental arrangement and technique to provide a like-for-like comparison. The parallel transfer using the p-channel CCD was then optimized using a trap pumping technique to identify the optimal operating conditions at 153 K.

Comparison between Equilibrium Voltage Step and Charge Pumping Techniques for Characterizing near Si-SiO2 Interface Traps

In conventional MOS structures, the interface region between silicon and its oxide contains defects which play an important role in the performance and reliability of the devices by acting as charge traps. Traps having response times greater than that of conventional (and so-called “fast”) interface traps are known as slow traps. These traps are supposed to exchange charges with the semiconductor by tunnelling, their response time depending on their energy level and distance from the interface. Due to their wide range of response times and depending on the measurement technique employed, they are often indistinguishable from fast ones or from fixed oxide charges.Several techniques have been used to characterize electrically these different kinds of traps in MOS capacitors or MOSFET structures. Recently, the study on MOS capacitors of current transients that follow the application of a small gate voltage step due to the change in the charge state of the traps has been proposed by Tanner & al. [1]. The technique was used to characterize traps generated in the oxide by constant current stressing [1]. A few years later, Spillane et al. [2] introduced the McWhorter tunnelling model [3] to evaluate oxide depth from the traps time constant and study the slow states density versus oxide depth.In this paper, after recalling the principle of the Equilibrium Voltage Step (EVS) technique, this technique is used to extract the profile in three dimensions (Nt, x, E) of the trap density near the Si-SiO2interface of a lightly stressed MOS structure (Fig. 1). This has been achieved using the models depicted in Refs. [2] and [4] using a device with a rather low interface states density.These results are summarized in two dimensions (Nt,x) in Fig. 2 where they are compared with those obtained with charge pumping (CP) [4], [5]. A good coherence between the results recorded using the two techniques is obtained. The traps densities measured using EVS are in the same order of magnitude as those obtained with CP. Both trap profiles show the same tendencies even though their shapes are somewhat different. From that point of view, CP may be more efficient in distinguishing between interface and near oxide traps. However, the shape of trap profiles extracted previously using current-DLTS [6] is very close to that measured here using EVS method. In this paper, these results will be compared and discussed.[1] P. Tanner, S. Dimitrijev, and H.B. Harrison, Electronics Letters, 31, 1880 (1995).[2] M. P. Spillane, S. Taylor and M. J. Uren, Microelectronic Engineering, 48, 155 (1999).[3] A. L. McWhorter, Semiconductor Surface Physics, Univ. Pennsylvania Press, 1957, pp. 207-228. [4] D. Bauza and Y. Maneglia, IEEE Trans. Electron Devices, 44, 2262 (1997).[5] Y. Maneglia, F. Rahmoune and D. Bauza, J. Appl. Phys., 97, 145021 (2005).[6] D. Bauza, J. Appl. Phys., 84, 6178 (1998).

Profiling of Channel-Hot-Carrier Stress-Induced Trap Distributions Along Channel and Gate Dielectric in High-$k$ Gated MOSFETs by a Modified Charge Pumping Technique

To better understand the channel-hot-carrier (CHC)-induced reliability problems, a modified charge-pumping (CP) technique is proposed to characterize the distribution profiles of trap generation in MOSFETs with high- k gate-stack. The effects of gate leakage current on CP measurements were minimized to ensure the correct CP data. While applying dynamic drain bias, the gate-induced drain leakage current is also considered to get correct CP data. Through the CP with dynamic drain bias and various gate pulse frequencies, the profiling of CHC stress-induced interface- and border-traps can be achieved. The CHC stress-induced interface trap generation appears along whole the channel but that-induced border trap generation is mainly located above the pinchoff region near the drain and decreases dramatically toward the center of the channel. Thus, the CHC stress causes quite localized border trap generation at the gate-edge region inside the high- k dielectric. The reliability data measured by CP with different gate voltage swings confirm that CHC stress causes interface trap generation through whole the channel and significant border trap generation at gate-edge region.

(Invited) AlGaN/GaN HEMT Reliability and Trap Detection Using Optical Pumping

Although the AlGaN/GaN HEMT continues to draw attention because of its high-thermal stability, extended frequency response, and high break-down voltage, it has not gained the full confidence of designers due to its inconsistent reliability. One of the prominent reliability issues that plague AlGaN/GaN HEMTs is the creation of traps that not only degrade performance, but can lead to device failure. By optically pumping the device, with different wavelengths of light in the visible spectrum (red, green, blue, and violet) and measuring the drain current response, trap energies, trap densities, and time constants are determined.The light sources used in the optical pumping technique consist of four low power lasers: red, green, blue, and violet. The response of the drain current to the illumination is measured using high-speed data acquisition equipment with sampling rates up to 100k samples/s. In the initial experiments a device was exposed to each laser independently from longest to shortest wavelength, i.e., red then green then blue then violet.AlGaN/GaN HEMTs with gates ranging from 0.125x150 to 0.170x150 microns were pumped before and after high temperature dc stress. The dc stress was at the bias point of VG=-2 and the channel power was maintained at one watt by adjusting the drain voltage at constant temperature of 150⁰C. Devices that degraded gradually have significant increases in the blue energy range which suggests an increase oxygen on nitrogen substitutional defects [M.A. Reshchikov and H. Morkoc; JAP 97, 061301 (2005)]. Other devices showed degradation with noisy fluctuations in drain current (up to 20 mApp), but when optically pumped, showed very little change from the pre-stress response. Trap creation is not suspected in the degradation in these parts, but may be a result of contact or final metal failure.Trap energies can be determined by analyzing the decay of the drain current after the part has been illuminated. Curve fitting techniques determine the time constants of the decaying curve and when measured at multiple temperatures, activation energies are determined with Arrhenius analysis. An example using this technique with the blue laser (450nm) at 10 temperatures showed a trap of 0.14eV which the literature suggests a carbon on gallium substitutional [Levinshtein, et al., Properties of Advanced Semiconductor Materials : Gan, Aln, InN, BN, SiC, SiGe, 1st ed. New York: Wiley-Interscience, 2001].The author gratefully acknowleges the support of a DOD MURI monitored by the AFOSR and colleagues who contributed to this work: Rick Deist, Dr. Brent Gila, and Prof. Steve Pearton.

Comparison between Equilibrium Voltage Step and Charge Pumping Techniques for Characterizing near Si-SiO2 Interface Traps

The Equilibrium Voltage Step (EVS) technique has been used for extraction of depth and energy concentration profile of traps situated in the oxide of a lightly stressed metal-oxide-semiconductor (MOS) structure. This has been achieved up to the very near Si-SiO2 interface. The results are discussed and compared with those obtained using charge pumping (CP) technique. A good agreement is achieved between the trap densities extracted using the two methods even though differences in the shape of the profiles can be observed. The results also very well agree with those published previously using current deep level transient spectroscopy (C-DLTS).

Pumping through Porous Hydrophobic/Oleophilic Materials: An Alternative Technology for Oil Spill Remediation

AbstractRecently, porous hydrophobic/oleophilic materials (PHOMs) have been shown to be the most promising candidates for cleaning up oil spills; however, due to their limited absorption capacity, a large quantity of PHOMs would be consumed in oil spill remediation, causing serious economic problems. In addition, the complicated and time‐consuming process of oil recovery from these sorbents is also an obstacle to their practical application. To solve the above problems, we apply external pumping on PHOMs to realize the continuous collection of oil spills in situ from the water surface with high speed and efficiency. Based on this novel design, oil/water separation and oil collection can be simultaneously achieved in the remediation of oil spills, and the oil sorption capacity is no longer limited to the volume and weight of the sorption material. This novel external pumping technique may bring PHOMs a step closer to practical application in oil spill remediation.

Pumping through Porous Hydrophobic/Oleophilic Materials: An Alternative Technology for Oil Spill Remediation

Recently, porous hydrophobic/oleophilic materials (PHOMs) have been shown to be the most promising candidates for cleaning up oil spills; however, due to their limited absorption capacity, a large quantity of PHOMs would be consumed in oil spill remediation, causing serious economic problems. In addition, the complicated and time-consuming process of oil recovery from these sorbents is also an obstacle to their practical application. To solve the above problems, we apply external pumping on PHOMs to realize the continuous collection of oil spills in situ from the water surface with high speed and efficiency. Based on this novel design, oil/water separation and oil collection can be simultaneously achieved in the remediation of oil spills, and the oil sorption capacity is no longer limited to the volume and weight of the sorption material. This novel external pumping technique may bring PHOMs a step closer to practical application in oil spill remediation.

Euler force actuation mechanism for siphon valving in compact disk-like microfluidic chips.

Based on the Euler force induced by the acceleration of compact disk (CD)-like microfluidic chip, this paper presents a novel actuation mechanism for siphon valving. At the preliminary stage of acceleration, the Euler force in the tangential direction of CD-like chip takes the primary place compared with the centrifugal force to function as the actuation of the flow, which fills the siphon and actuates the siphon valving. The Euler force actuation mechanism is demonstrated by the numerical solution of the phase-field based mathematical model for the flow in siphon valve. In addition, experimental validation is implemented in the polymethylmethacrylate-based CD-like microfluidic chip manufactured using CO2 laser engraving technique. To prove the application of the proposed Euler force actuation mechanism, whole blood separation and plasma extraction has been conducted using the Euler force actuated siphon valving. The newly introduced actuation mechanism overcomes the dependence on hydrophilic capillary filling of siphon by avoiding external manipulation or surface treatments of polymeric material. The sacrifice for highly integrated processing in pneumatic pumping technique is also prevented by excluding the volume-occupied compressed air chamber.

Impact of Hot Carrier Degradation and Positive Bias Temperature Stress on Lateral 4H-SiC nMOSFETs

We study the impact of positive bias temperature stress and hot carrier stress on lateral 4H-SiC nMOSFETs. These degradation mechanisms are prominent in silicon based devices where both create oxide as well as interface traps. For SiC MOSFETs only limited information regarding these mechanisms is available. We transfer the charge pumping technique, known from Si MOSFETs, reliably to SiC MOSFETs to learn about the nature of the stress induced defects.

Investigation of interface, shallow and deep oxide traps under NBTI stress using charge pumping technique

By extracting and eliminating the geometric component from the charge pumping current (ICP) in on-the-fly oxide trap method (OTFOT), we have been able to demonstrate that both interface (ΔNit) and deep hole oxide traps (ΔNotD) induced by the negative bias temperature instability (NBTI) are principally located in the lightly doped drain region (LDD region) and they do not show any noticeable increase with stress time in the effective channel region. However, we have shown that the shallow hole oxide traps (ΔNotS) induced by NBTI are created in the whole of the channel.

Conversion of pure spin current to charge current in amorphous bismuth

Spin Hall angle and spin diffusion length in amorphous bismuth (Bi) are investigated by using conversion of a pure spin current to a charge current in a spin pumping technique. In Bi/Ni80Fe20/Si(100) sample, a clear direct current (DC) electromotive force due to the inverse spin Hall effect of the Bi layer is observed at room temperature under a ferromagnetic resonance condition of the Ni80Fe20 layer. From the Bi thickness dependence of the DC electromotive force, the spin Hall angle and the spin diffusion length of the amorphous Bi film are estimated to be 0.02 and 8 nm, respectively.

A high-sensitivity push-pull magnetometer

We describe our approach to atomic magnetometry based on the push-pull optical pumping technique. Cesium vapor is pumped and probed by a resonant laser beam whose circular polarization is modulated synchronously with the spin evolution dynamics induced by a static magnetic field. The magnetometer is operated in a phase-locked loop, and it has an intrinsic sensitivity below 20fT/Hz, using a room temperature paraffin-coated cell. We use the magnetometer to monitor magnetic field fluctuations with a sensitivity of 300fT/Hz.

Characterization of Radiation Damage in Carbon Nanotube Field-Effect Transistors

<?Pub Dtl=""?> Carbon nanotube field-effect transistors with <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\rm Al}_{2}{\rm O}_{3}$</tex></formula> gate dielectrics have been characterized before and after 1 MeV electron irradiation. Pre-irradiation interface trap densities determined by charge pumping measurements were on the order of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10^{11}~\hbox{cm}^{\hbox{-}2}\hbox{eV}^{\hbox{-}1}$</tex> </formula> . Following irradiation to fluences of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$10^{16}~\hbox{e/cm}^2$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$10^{17}~\hbox{e/cm}^2$</tex></formula> , the measured interface trap densities decreased significantly for all devices. This result is largely attributed to the removal of molecular adsorbates that act as trap sites on the nanotubes (de-doping) while the devices are irradiated under vacuum. Negative shifts in the transistor <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$I\hbox{-}V$</tex></formula> curves with irradiation indicate radiation-induced hole trapping in the gate dielectric, with some recovery after room temperature annealing. No significant changes were observed in the Raman spectra following irradiation, indicating the intrinsic structure of the carbon nanotubes remained unchanged. These results suggest that the radiation response of these devices is dominated by charge trapping in the oxide layers and at the carbon nanotube surfaces. Furthermore, the charge pumping technique can be used as a tool for probing surface adsorbates in carbon nanotube devices, and elucidating their role in the device radiation response.

Output Signal Power Analysis in Erbium-Doped Fiber Amplifier with Pump Power and Length Variation Using Various Pumping Techniques

The scope of this paper is to analyze the output signal power with pump power and length variation in cascaded EDFA simulation model performance. This paper describes the simulation model of Erbium-Doped Fiber Amplifier (EDFA) of variable lengths (10 m, 50 m, and 120 m) with dual pumping techniques (dual forward pumping with two 980 nm wavelengths, dual forward and backward pumping with two 980 nm wavelengths) and Tri-pumping techniques. The simulation models consist of input source and pump power coupled by WDM coupler which gives optimized signal power in the above-mentioned simulation model. The simulation model consists of source with multiple wavelengths (1520 nm–1618 nm), pumping source with the wavelength 980 nm, isolator, and filter. The resulting models accurately represent EDFA optimized output signal power. Simulation results show that choosing careful fiber length 120 m and pump power 1 W in dual pumping provided 0.07 W optimized output signal power compared to other pumping techniques.

High-k shallow traps observed by charge pumping with varying discharging times

In this paper, we investigate the influence of falling time and base level time on high-k bulk shallow traps measured by charge pumping technique in n-channel metal-oxide-semiconductor field-effect transistors with HfO2/metal gate stacks. NT-Vhigh level characteristic curves with different duty ratios indicate that the electron detrapping time dominates the value of NT for extra contribution of Icp traps. NT is the number of traps, and Icp is charge pumping current. By fitting discharge formula at different temperatures, the results show that extra contribution of Icp traps at high voltage are in fact high-k bulk shallow traps. This is also verified through a comparison of different interlayer thicknesses and different TixN1−x metal gate concentrations. Next, NT-Vhigh level characteristic curves with different falling times (tfalling time) and base level times (tbase level) show that extra contribution of Icp traps decrease with an increase in tfalling time. By fitting discharge formula for different tfalling time, the results show that electrons trapped in high-k bulk shallow traps first discharge to the channel and then to source and drain during tfalling time. This current cannot be measured by the charge pumping technique. Subsequent measurements of NT by charge pumping technique at tbase level reveal a remainder of electrons trapped in high-k bulk shallow traps.

Spectral Engineering of Slow Light, Cavity Line Narrowing, and Pulse Compression

More than 4 orders of magnitude of cavity-linewidth narrowing in a rare-earth-ion-doped crystal cavity, emanating from strong intracavity dispersion caused by off-resonant interaction with dopant ions, is demonstrated. The dispersion profiles are engineered using optical pumping techniques creating significant semipermanent but reprogrammable changes of the rare-earth absorption profiles. Several cavity modes are shown within the spectral transmission window. Several possible applications of this phenomenon are discussed.

The uncertainty of mass discharge measurements using pumping methods under simplified conditions

Mass discharge measurements at contaminated sites have been used to assist with site management decisions, and can be divided into two broad categories: point-scale measurement techniques and pumping methods. Pumping methods can be sub-divided based on the pumping procedures used into sequential, concurrent, and tandem circulating well categories. Recent work has investigated the uncertainty of point measurement methods, and to a lesser extent, pumping methods. However, the focus of this study was a direct comparison of uncertainty between the various pumping method approaches that have been used, as well as a comparison of uncertainty between pumping and point measurement methods. Mass discharge measurement error was investigated using a Monte Carlo modeling analysis as a function of the contaminant plume position and width, and as a function of the pumping conditions used in the different pumping tests. Results indicated that for the conditions investigated, uncertainty in mass discharge estimates based on pumping methods was 1.3 to 16 times less than point measurement method uncertainty, and that a sequential pumping approach resulted in 5 to 12 times less uncertainty than the concurrent pumping or tandem circulating well approaches. Uncertainty was also investigated as a function of the plume width relative to well spacing. For a given well spacing, uncertainty decreased for all methods as the plume width increased, and comparable levels of uncertainty between point measurement and pumping methods were obtained when three wells were distributed across the plume. A hybrid pumping technique in which alternate wells were pumped concurrently in two separate campaigns yielded similar uncertainty to the sequential pumping approach. This suggests that the hybrid approach can be used to capitalize on the advantages of sequential pumping yet minimize the overall test duration.

New continuous air pumping technique to improve clinical outcomes of descemet-stripping automated endothelial keratoplasty in asian patients with previous ahmed glaucoma valve implantation.

BackgroundTo evaluate the outcomes of Descemet-stripping automated endothelial keratoplasty (DSAEK) with the use of continuous air pumping technique in Asian eyes with previous Ahmed glaucoma valve implantation.MethodsThe DSAEK procedure was modified in that complete air retention of the anterior chamber was maintained for 10 min using continuous air pumping at 30 mm Hg. The primary outcome measurement was graft survival, and postoperative clinical features including, rate of graft detachment, endothelial cell count, intraocular pressure (IOP), surgical time and cup/disc ratio were also recorded.ResultsA total of 13 eyes of 13 patients which underwent modified DSAEK and 6 eyes of 6 patients which underwent conventional DSAEK were included. There was a significant difference in graft survival curves between two groups (P = 0.029); the 1-year graft survival rates were estimated as 100% and 66.7% for patients with modified DSAEK and those with traditional DSAEK, respectively. The rate of graft detachment were 0% and 33.3% for the modified DSAEK and conventional DSAEK groups, respectively (P = 0.088). The significantly lowered surgical time for air tamponade was noted in the modified DSAEK group compared to that in the conventional DSAEK group [median (IQR): 10.0 (10.0, 10.0) min vs. 24.5 (22.0, 27.0) min; P<0.001] Postoperatively, patients in the modified DSAEK group had significantly lower IOP as compared to the conventional DSAEK group [12.0 (11.0, 15.0) mm Hg vs. 16.0 (15.0, 18.0) mm Hg; P = 0.047]. Modified DSAEK patients had higher endothelial cell counts as compared to conventional DSAEK patients [2148.0 (1964.0, 2218.0) vs. 1529.0 (713.0, 2014.0)], but the difference did not reach statistical significance (P = 0.072).ConclusionsNew continuous air pumping technique in DSAEK can be performed safely and effectively in patients with prior GDDs placement who have corneal failure.

EHD Conduction-Driven Enhancement of Critical Heat Flux in Pool Boiling

When a liquid undergoes pool boiling, there is a critical heat flux at which the departing vapor bubbles start to inhibit the flow of fresh liquid to the heated surface. A number of methods to enhance the critical heat flux of pool boiling have been considered, including electrohydrodynamic (EHD) enhancement. In these studies, the heater surface has generally been electrically grounded, and a high-voltage electrode has been placed a short distance away from the heater surface to create a high intensity field near the heater. The resulting configuration produces a dielectrophoretic force on the vapor bubbles to promote vapor removal. However, the high-voltage electrode can also act as a physical barrier to the incoming liquid and the departing vapor. This paper considers a different technique for the EHD enhancement of critical heat flux. EHD conduction pumping-type electrodes are embedded into the heater surface and used to pump liquid along the heated surface. The embedding of this pumping technique into the heater thereby promotes the wetting of the surface and subsequently delivers sizable enhancements to the heat transfer. The effect of a variety of applied voltages on the boiling curve and the critical heat flux point are quantified. An analytical model is developed to explain the enhancement effect.