Showing papers on "Breakdown voltage published in 2016"

Field-Plated Ga 2 O 3 MOSFETs With a Breakdown Voltage of Over 750 V

Abstract: Depletion-mode field-plated Ga2O3 metal–oxide–semiconductor field-effect transistors were demonstrated for the first time. Substantial enhancement in breakdown voltage was achieved with a gate-connected field plate. The device channels, formed by selective-area Si ion implantation doping of an undoped Ga2O3 epilayer, were electrically isolated by the highly resistive epilayer without mesa etching. Effective surface passivation and high Ga2O3 material quality contributed to the absence of drain current collapse. The transistors exhibited an off-state breakdown voltage of 755 V, a high drain current on/off ratio of over $10^{9}$ , and stable high temperature operation against 300°C thermal stress.

Field-Plated Ga 2 O 3 MOSFETs With a Breakdown Voltage of Over 750 V

Abstract: Depletion-mode field-plated Ga2O3 metal–oxide–semiconductor field-effect transistors were demonstrated for the first time. Substantial enhancement in breakdown voltage was achieved with a gate-connected field plate. The device channels, formed by selective-area Si ion implantation doping of an undoped Ga2O3 epilayer, were electrically isolated by the highly resistive epilayer without mesa etching. Effective surface passivation and high Ga2O3 material quality contributed to the absence of drain current collapse. The transistors exhibited an off-state breakdown voltage of 755 V, a high drain current on/off ratio of over $10^{9}$ , and stable high temperature operation against 300°C thermal stress.

Enhancement-mode Ga2O3 wrap-gate fin field-effect transistors on native (100) β-Ga2O3 substrate with high breakdown voltage

Abstract: Sn-doped gallium oxide (Ga2O3) wrap-gate fin-array field-effect transistors (finFETs) were formed by top-down BCl3 plasma etching on a native semi-insulating Mg-doped (100) β-Ga2O3 substrate. The fin channels have a triangular cross-section and are approximately 300 nm wide and 200 nm tall. FinFETs, with 20 nm Al2O3 gate dielectric and ∼2 μm wrap-gate, demonstrate normally-off operation with a threshold voltage between 0 and +1 V during high-voltage operation. The ION/IOFF ratio is greater than 105 and is mainly limited by high on-resistance that can be significantly improved. At VG = 0, a finFET with 21 μm gate-drain spacing achieved a three-terminal breakdown voltage exceeding 600 V without a field-plate.

Schottky barrier diodes of corundum-structured gallium oxide showing on-resistance of 0.1 mΩ·cm2 grown by MIST EPITAXY®

Abstract: Thin-film corundum-structured gallium oxide (α-Ga2O3) Schottky barrier diodes (SBDs) were fabricated by growing α-Ga2O3 layers on sapphire substrates by the safe, low-cost, and energy-saving MIST EPITAXY® technique, followed by lifting off the α-Ga2O3 layers from the substrates. The SBDs exhibited on-resistance and breakdown voltage of 0.1 mΩcm2 and 531 V (SBD1) or 0.4 mΩcm2 and 855 V (SBD2), respectively. These results will encourage the future evolution of low-cost and high-performance SBDs with α-Ga2O3.

High Performance Depletion/Enhancement-Mode beta-Ga2O3 on Insulator (GOOI) Field-effect Transistors with Record Drain Currents of 600/450 mA/mm

Abstract: In this letter, we report on high performance depletion/enhancement (D/E)-mode beta-Ga2O3 on insulator (GOOI) field-effect transistors (FETs) with record high drain currents (ID) of 600/450 mA/mm, which are nearly one order of magnitude higher than any other reported ID values. The threshold voltage (VT) can be modulated by varying the thickness of the beta-Ga2O3 films and the E-mode GOOI FET can be simply achieved by shrinking the beta-Ga2O3 film thickness. Benefiting from the good interface between beta-Ga2O3 and SiO2 and wide bandgap of beta-Ga2O3, a negligible transfer characteristic hysteresis, high ID on/off ratio of 10^10, and low subthreshold swing of 140 mV/dec for a 300 nm thick SiO2 are observed. E-mode GOOI FET with source to drain spacing of 0.9 um demonstrates a breakdown voltage of 185 V and an average electric field (E) of 2 MV/cm, showing the great promise of GOOI FET for future power devices.

Compact Model of Dielectric Breakdown in Spin-Transfer Torque Magnetic Tunnel Junction

Abstract: Spin-transfer torque magnetic tunnel junction (MTJ) is a promising candidate for nonvolatile memories thanks to its high speed, low power, infinite endurance, and easy integration with CMOS circuits. However, a relatively high current flowing through an MTJ is always required by most of the switching mechanisms, which results in a high electric field in the MTJ and a significant self-heating effect. This may lead to the dielectric breakdown of the ultrathin ( $\sim 1$ nm) oxide barrier in the MTJ and cause functional errors of hybrid CMOS/MTJ circuits. This paper analyzes the physical mechanisms of time-dependent dielectric breakdown (TDDB) in an oxide barrier and proposes an SPICE-compact model of the MTJ. The simulation results show great consistency with the experimental measurements. This model can be used to execute a more realistic design according to the constraints obtained from simulation. The users can estimate the lifetime, the operation voltage margin, and the failure probability caused by TDDB in the MTJ-based circuits.

High-voltage vertical GaN Schottky diode enabled by low-carbon metal-organic chemical vapor deposition growth

Abstract: Vertical GaN Schottky barrier diode (SBD) structures were grown by metal-organic chemical vapor deposition on free-standing GaN substrates. The carbon doping effect on SBD performance was studied by adjusting the growth conditions and spanning the carbon doping concentration between ≤3 × 1015 cm−3 and 3 × 1019 cm−3. Using the optimized growth conditions that resulted in the lowest carbon incorporation, a vertical GaN SBD with a 6-μm drift layer was fabricated. A low turn-on voltage of 0.77 V with a breakdown voltage over 800 V was obtained from the device.

An AlN/Al0.85Ga0.15N high electron mobility transistor

Abstract: An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al0.85Ga0.15N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high Ion/Ioff current ratio greater than 107 and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. The room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.

25 Gbps low-voltage waveguide Si–Ge avalanche photodiode

Abstract: Silicon-germanium (Si–Ge)-based avalanche photodiodes (APDs) have shown a significant improvement in receiver sensitivity compared to their III–V counterparts due to the superior impact ionization property of silicon. However, conventional Si–Ge APDs typically operate at high voltages and low speed, limiting the application of this technology to data communication. In this paper, we present a waveguide Si–Ge avalanche photodiode using a thin silicon multiplication region with a breakdown voltage of −10 V, a speed of 25 GHz, and a gain-bandwidth product (GBP) of 276 GHz. At 1550 nm, sensitivities of −25 dBm and −16 dBm are achieved at 12.5 Gbps and 25 Gbps, respectively. This design will enable implementation of Si–Ge APDs for optical interconnects in data centers and high-performance computers, allowing significant reductions in aggregate system laser power (and therefore cost).

2.07-kV AlGaN/GaN Schottky Barrier Diodes on Silicon With High Baliga’s Figure-of-Merit

Abstract: In this letter, we demonstrate high-performance AlGaN/GaN Schottky barrier diodes (SBDs) on Si substrate with a recessed-anode structure for reduced turn-on voltage $V_{\mathrm {ON}}$ . The impact of the surface roughness after the recessed-anode formation on device characteristics is investigated. An improved surface condition can reduce the leakage current and enhance the breakdown voltage simultaneously. A low turn-on voltage of only 0.73 V can be obtained with a 50-nm recess depth. In addition, the different lengths of Schottky extension acting like a field plate are investigated. A high reverse breakdown voltage of 2070 V and a low specific ON-resistance of 3.8 $\text{m}\Omega \cdot \textrm {cm}^{2}$ yield an excellent Baliga’s figure of merit of 1127 MW/cm2, which can be attributed to the low surface roughness of only 0.6 nm and also a proper Schottky extension of 2 $\mu \text{m}$ to alleviate the peak electric field intensity in the SBDs.

Zener Tunneling and Photoresponse of a WS2/Si van der Waals Heterojunction.

Abstract: Van der Waals heterostructures built from two-dimensional materials on a conventional semiconductor offer novel electronic and optoelectronic properties for next-generation information devices. Here we report that by simply stacking a vapor-phase-synthesized multilayer n-type WS2 film onto a p-type Si substrate, a high-responsivity Zener photodiode can be achieved. We find that above a small reverse threshold voltage of 0.5 V, the fabricated heterojunction exhibits Zener tunneling behavior which was confirmed by its negative temperature coefficient of the breakdown voltage. The WS2/Si heterojunction working in the Zener breakdown regime shows a stable and linear photoresponse, a broadband photoresponse ranging from 340 to 1100 nm with a maximum photoresponsivity of 5.7 A/W at 660 nm and a fast response speed of 670 μs. Such high performance can be attributed to the ultrathin depletion layer involved in the WS2/Si p–n junction, on which a strong electric field can be created even with a small reverse volta...

Statistical investigation of AC breakdown voltage of nanofluids compared with mineral and natural ester oil

Abstract: In this study, three different insulating liquids, natural ester, mineral oil which is currently used by the Public Power Corporation of Greece and a nanofluid of surface coated Fe3O4 nanoparticles into a natural ester matrix, were subjected to AC voltage stress and their statistical breakdown voltage was measured and compared. Three different electrode configurations were used during the measurements in order to study the effect of non-uniform fields on the breakdown voltage distribution. Four different statistical distributions were used for the statistical processing of the experimental results. The two of them were the frequently used normal and Weibull distributions; in addition, Gumbel and generalised extreme value (GEV) function distributions were studied. It was shown that, in most cases, the experimental data followed GEV and Weibull functions rather than normal or Gumbel. Therefore, GEV statistics fits indiscriminately better to the experimental results concerning breakdown voltage, for the three different electrodes configuration and the three understudied insulating oils. The experimental results indicated that nanofluid has better performance, in terms of dielectric breakdown voltage, compared with natural ester oil and mineral oil, hence nanofluid is considered as a potential substitute of the conventional dielectric liquids, with enhanced properties and prospects.

Fully Vertical GaN p-i-n Diodes Using GaN-on-Si Epilayers

Abstract: Using GaN-on-Si epilayers, for the first time, fully vertical p-i-n diodes are demonstrated after Si substrate removal, transfer, and n-electrode formation at the top of the device. After SiO2 sidewall passivation, the vertical p-i-n diodes, with n-GaN facing up, exhibit $V_{{\mathrm{\scriptscriptstyle ON}}}$ of 3.35 V at 1 A/cm2, a low differential on-resistance of 3.3 $\text{m}\Omega $ cm2 at 300 A/cm2, and a breakdown voltage of 350 V. The corresponding Baliga's figure of merit is 37.0 MW/cm2, a very good value for GaN-based p-i-n rectifiers grown on Si substrates. The results indicate that fully vertical rectifiers using GaN-on-Si epilayers have great potential in achieving cost-effective GaN devices for high-power and high-voltage applications.

Space Charge Modulated Electrical Breakdown

Abstract: Electrical breakdown is one of the most important physical phenomena in electrical and electronic engineering. Since the early 20th century, many theories and models of electrical breakdown have been proposed, but the origin of one key issue, that the explanation for dc breakdown strength being twice or higher than ac breakdown strength in insulating materials, remains unclear. Here, by employing a bipolar charge transport model, we investigate the space charge dynamics in both dc and ac breakdown processes. We demonstrate the differences in charge accumulations under both dc and ac stresses and estimate the breakdown strength, which is modulated by the electric field distortion induced by space charge. It is concluded that dc breakdown initializes in the bulk whereas ac breakdown initializes in the vicinity of the sample-electrode interface. Compared with dc breakdown, the lower breakdown strength under ac stress and the decreasing breakdown strength with an increase in applied frequency, are both attributed to the electric field distortion induced by space charges located in the vicinity of the electrodes.

Capacitance Modeling in Dual Field-Plate Power GaN HEMT for Accurate Switching Behavior

Abstract: In this paper, a surface-potential-based compact model is proposed for the capacitance of an AlGaN/GaN high-electron mobility transistor (HEMT) dual field-plate (FP) structure, i.e., with gate and source FPs. FP incorporation in a HEMT gives an improvement in terms of enhanced breakdown voltage, reduced gate leakage, and so on, but it affects the capacitive nature of the device, particularly by bringing into existence in a subthreshold region of operation, a feedback miller capacitance between the gate and the drain, and also a capacitance between the drain and the source, therefore, affecting switching characteristics. Here, we model the bias dependence of the terminal capacitances, wherein the expressions developed for intrinsic charges required for capacitance derivation are analytical and physics-based in nature and valid for all regions of device operation. The proposed model, implemented in Verilog-A, is in excellent agreement with the measured data for different temperatures.

Novel GaN trench MIS barrier Schottky rectifiers with implanted field rings

Abstract: We demonstrate a novel GaN vertical Schottky rectifier with trench MIS structures and trench field rings. The new structure greatly enhanced the reverse blocking characteristics while maintaining a Schottky-like good forward conduction. The reverse leakage current improved beyond 104-fold and the breakdown voltage increased from 400 V to 700 V, while the low turn-on voltage (0.8 V) and on-resistance (2 mΩ·cm2) were retained. High-temperature operation up to 250 oC and fast switching performance were also demonstrated. This new device shows great potential for high-power and high-frequency applications.

Normally-off p-GaN/AlGaN/GaN high electron mobility transistors using hydrogen plasma treatment

Abstract: In this letter, we report a method by introducing hydrogen plasma treatment to realize normally-off p-GaN/AlGaN/GaN HEMT devices. Instead of using etching technology, hydrogen plasma was adopted to compensate holes in the p-GaN above the two dimensional electron gas (2DEG) channel to release electrons in the 2DEG channel and form high-resistivity area to reduce leakage current and increase gate control capability. The fabricated p-GaN/AlGaN/GaN HEMT exhibits normally-off operation with a threshold voltage of 1.75 V, a subthreshold swing of 90 mV/dec, a maximum transconductance of 73.1 mS/mm, an ON/OFF ratio of 1 × 107, a breakdown voltage of 393 V, and a maximum drain current density of 188 mA/mm at a gate bias of 6 V. The comparison of the two processes of hydrogen plasma treatment and p-GaN etching has also been made in this work.

Performance Optimization of Au-Free Lateral AlGaN/GaN Schottky Barrier Diode With Gated Edge Termination on 200-mm Silicon Substrate

Abstract: In this paper, a further leakage reduction of AlGaN/GaN Schottky barrier diodes with gated edge termination (GET-SBDs) has been achieved by optimizing the physical vapor deposited TiN as the anode metal without severe degradation of on -state characteristics. The optimized GET-SBD multifinger power diodes with 10 mm anode width deliver $\sim 4$ A at 2 V and show a median leakage of 1.3 $\mu \text{A}$ at 25 °C and 3.8 $\mu \text{A}$ at 150 °C measured at a reverse voltage of −200 V. The temperature-dependent leakage of Si, SiC, and our GaN power diodes has been compared. The breakdown voltage (BV) of GET-SBDs was evaluated by the variation of anode-to-cathode spacing ( $L_{\mathrm{ AC}}$ ) and the length of field plate. We observed a saturated BV of $\sim 600$ V for the GET-SBDs with $L_{\mathrm{ AC}}$ larger than 5 $\mu \text{m}$ . The GET-SBD breakdown mechanism is shown to be determined by the parasitic vertical leakage current through the 2.8 $\mu \text{m}$ -thick buffer layers measured with a grounding substrate. Furthermore, we show that the forward voltage of GET-SBDs can be improved by shrinking the lateral dimension of the edge termination due to reduced series resistance. The leakage current shows no dependence on the layout dimension $L_{G}$ (from 2 to 0.75 $\mu \text{m}$ ) and remains at a value of $\sim 10$ nA/mm. The optimized Au-free GET-SBD with low leakage current and improved forward voltage competes with high-performance lateral AlGaN/GaN SBDs reported in the literature.

A Near Ideal Edge Termination Technique for 4500V 4H-SiC Devices: The Hybrid Junction Termination Extension

Abstract: This letter presents a new edge termination technique named a hybrid junction termination extension (Hybrid-JTE), which combines ring-assisted JTE and multiple floating zone JTE Based on the parameters of the drift layer specified by the wafer vendor, the measured breakdown voltage of the fabricated p-i-n diode using the Hybrid-JTE is as high as 5450 V, which is close (~99%) of the ideal parallel plane p-n junction Furthermore, measured breakdown voltages from randomly chosen 32 p-i-n diodes across the wafer show very tight distribution: 29 diodes provide breakdown voltages higher than 5000 V at $100~\mu \text{A}$

OG-FET: An In-Situ ${O}$ xide, ${G}$ aN Interlayer-Based Vertical Trench MOSFET

Abstract: In this letter, a novel device design to achieve both low ON-resistance and enhancement mode operation in a vertical GaN FET is demonstrated. In the traditional trench MOSFET structure, a dielectric is deposited on an n-p-n trenched structure and the channel forms via p-GaN inversion at the dielectric/p-GaN interface. However, this results in a relatively high ON-resistance due to poor electron mobility in the channel. By changing the structure to include a metal-organic chemical vapor deposition (MOCVD)-regrown Un-intentionally Doped (UID)-GaN interlayer followed by an in-situ dielectric (MOCVD Al2O3) cap on the n-p-n trenched structure, a pathway (channel) for enhanced electron mobility is created, resulting in reduced ON-resistance. Preliminary results for this device design demonstrated almost 60% reduction in the ON-resistance and similar breakdown voltage compared with a traditional trench MOSFET structure while maintaining normally off operation with a threshold voltage of 2 V.

Vertical architecture for enhancement mode power transistors based on GaN nanowires

Abstract: The demonstration of vertical GaN wrap-around gated field-effect transistors using GaN nanowires is reported. The nanowires with smooth a-plane sidewalls have hexagonal geometry made by top-down etching. A 7-nanowire transistor exhibits enhancement mode operation with threshold voltage of 1.2 V, on/off current ratio as high as 108, and subthreshold slope as small as 68 mV/dec. Although there is space charge limited current behavior at small source-drain voltages (Vds), the drain current (Id) and transconductance (gm) reach up to 314 mA/mm and 125 mS/mm, respectively, when normalized with hexagonal nanowire circumference. The measured breakdown voltage is around 140 V. This vertical approach provides a way to next-generation GaN-based power devices.

Preparation of Three Types of Transformer Oil-Based Nanofluids and Comparative Study on the Effect of Nanoparticle Concentrations on Insulating Property of Transformer Oil

Abstract: Nanofluids have the potential to become the alternatives of conventional transformer oil for their exquisite electrical and thermal properties. Three kinds of nanoparticles with distinct conductivities, namely, nonconductive nanoparticle Al2O3, conductive nanoparticle Fe3O4, and semiconductive nanoparticle TiO2, with different concentrations from 5% to 40% w/v were selected and suspended into transformer oil to develop nanofluids. The lightening impulse breakdown strengths of the oil samples with and without nanoparticles were measured according to IEC standard methods. The positive impulse breakdown strength indicated that breakdown strength is first increased up to the maximum value at certain concentration and then starts decreasing. The results of negative impulse breakdown manifested that the breakdown voltages of nanofluids with different concentrations were less than the breakdown voltage of pure transformer oil. Different effect mechanisms of dielectric and conductive nanoparticles were also used to describe the difference among three prepared nanofluids.

Scaling laws for gas breakdown for nanoscale to microscale gaps at atmospheric pressure

Abstract: Electronics miniaturization motivates gas breakdown predictions for microscale and smaller gaps, since traditional breakdown theory fails when gap size, d, is smaller than ∼15 μm at atmospheric pressure, patm. We perform a matched asymptotic analysis to derive analytic expressions for breakdown voltage, Vb, at patm for 1 nm ≤ d ≤ 35 μm. We obtain excellent agreement between numerical, analytic, and particle-in-cell simulations for argon, and show Vb decreasing as d → 0, instead of increasing as predicted by Paschen's law. This work provides an analytic framework for determining Vb at atmospheric pressure for various gap distances that may be extended to other gases.

High breakdown voltage p–n diodes on GaN on sapphire by MOCVD

Abstract: In order to achieve high breakdown voltage in GaN vertical power devices, low threading dislocation density and low background carrier concentration is required. This work demonstrates a decrease in the background carrier concentration and threading dislocation density (TDD) with an increase in the thickness of un-intentionally doped (UID) GaN grown on sapphire. p–n diodes grown and fabricated on this epi, using 4.8 µm UID GaN, showed a breakdown voltage of 730 V, breakdown field of 1.75 MV cm−1 and an on-resistance of 5.1 m Ω cm2. The figure of merit (FOM), VBR2/RON, thus obtained is approximately 105 MW cm−2. This is the highest reported FOM value for p–n diodes on GaN on sapphire or Si. Lowering the carrier concentration and dislocation density is thus shown to be critical for achieving high breakdown voltages on GaN on sapphire.

Effect of TiO 2 nanoparticles on streamer propagation in transformer oil under lightning impulse voltage

Abstract: Recent experiments have shown that some nanoparticles can influence the breakdown strength of transformer oil under lightning impulse voltage. To reveal the working mechanism, this paper presents an experimental study on the effect of TiO2 nanoparticles on the impulse breakdown strength and prebreakdown streamer propagation process in transformer oil-based nanofluid under both positive and negative lightning impulse voltage. The test results verify that the modification of nanoparticles on breakdown strength of transformer oil has a distinct polar effect: positive breakdown voltage of nanofluid is increased by up to 30.8%, whereas the negative one is decreased by 6.8%. Streamer shape, propagation length and velocity in both pure oil and nanofluid were investigated using the shadowgraph technique. It is revealed that the propagation characteristics of positive and negative streamers in nanofluid are markedly affected by the addition of TiO2 nanoparticles. The positive streamers in nanofluid form a bush-like structure with thicker and denser branches, developing much slower than tree-like streamers in pure oil. While negative streamers in nanofluid have a tree-like shape with much longer branches, propagating faster than the original bush-like streamer in pure oil. These differences in streamer propagation characteristics and breakdown strength in pure oil and nanofluid are closely related to the change of space charge distribution caused by shallow trap in nanofluid. More negative charges are formed through capturing fast electrons into slow electrons in shallow traps induced by the presence of TiO2 nanoparticles, which change the local electric field in front of the streamer tip. Thus, streamer propagation process in nanofluid is dramatically modified, leading to the change in breakdown strength.

4H-SiC Trench MOSFET With L-Shaped Gate

Abstract: A novel 4H-SiC trench metal–oxide–semiconductor field-effect transistor (MOSFET) with an L-shaped gate (LSG) is proposed and studied via numerical simulations in this letter. Adoption of an additional LSG region that surrounds the bottom corner of the trench allows the peak electric field in the SiO2 dielectric to be significantly relieved by charge compensation, and the device breakdown voltage can be greatly enhanced without causing significant degradation of the output characteristics. In high-voltage blocking states, the electric field at the bottom corner of the trench is weakened, which leads to improved device performance. The peak electric field value in the SiO2 dielectric decreases by 32.3% when compared with that of a conventional 4H-SiC trench MOSFET, while the breakdown voltage increases by 80.4%.

Determination of the electric field strength of filamentary DBDs by CARS-based four-wave mixing

Abstract: It is demonstrated that a four-wave mixing technique based on coherent anti-Stokes Raman spectroscopy (CARS) can determine the electric field strength of a pulsed-driven filamentary dielectric barrier discharge (DBD) of 1 mm gap, using hydrogen as a tracer medium in nitrogen at atmospheric pressure. The measurements are presented for a hydrogen admixture of 10%, but even 5% H2 admixture delivers sufficient infrared signals. The lasers do not affect the discharge by photoionization or by other radiation-induced processes. The absolute values of the electric field strength can be determined by the calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. This procedure also enables the determination of the applied breakdown voltage. The alteration of the electric field is observed during the internal polarity reversal and the breakdown process. One advantage of the CARS technique over emission-based methods is that it can be used independently of emission, e.g. in the pre-phase and in between two consecutive discharges, where no emission occurs at all.

Experimental studies on power frequency breakdown voltage of CF3I/N2 mixed gas under different electric fields

Abstract: To verify the feasibility of replacing SF6 by CF3I/N2, we compared their power frequency breakdown performance with the influence of gas pressure, mixing ratio, and electric field utilization coefficient. Under different electric fields and mixing ratios, the power frequency breakdown voltage of CF3I/N2 increases linearly along with gas pressure. Besides, with the rise of the electric field utilization coefficient, the linear growth rate of breakdown voltage along with gas pressure gradually rises. The sensitivity of pure CF3I to electric field is particularly high and can be improved by the addition of N2. The mixture 30% CF3I/70% N2 at 0.3 MPa could replace pure SF6 in equipment requiring a low insulation, but the gas pressure or the content of CF3I need to be increased for higher insulation requirements.

A 25Gbps low-voltage waveguide Si-Ge avalanche photodiode

Abstract: We demonstrate a waveguide Si-Ge avalanche photodiode with a breakdown voltage of −10V, a speed of 25GHz, and a gain-bandwidth product of 276GHz. The APD optical receiver achieved sensitivities of −25dBm and −16dBm at 12.5Gbps and 25Gbps at 1550nm, respectively.