High Reverse Blocking Voltage Research Articles

FEM-based analysis of avalanche ruggedness of high voltage SiC Merged-PiN-Schottky and Junction-Barrier-Schottky diodes

Through comprehensive experimental measurements and TCAD simulation, it is shown that the avalanche ruggedness of SiC MPS & JBS diodes outperforms that of closely rated Silicon PiN diodes taking advantage of the wide-bandgap properties of SiC which leads to a high ionization and activation energy given the strong covalent bonds. Although the MPS diode structure favours a high reverse blocking voltage with small leakage current and a high current conduction, the localise current crowding caused by the multiple P+ implanted region leads to the avalanche breakdown at lower load currents than the SiC JBS diode. The results of Silvaco TCAD Finite Element modellings have a good agreement with the experimental measurements, indicating that SiC JBS diode can withstand the high junction temperature induced by avalanche in line with the calculated avalanche energy.

A High Reverse Breakdown Voltage p-GaN Gate HEMT with Field Control Drain

In this work, a high reverse blocking voltage (BV R) p-GaN gate high electron mobility transistor with field control drain (FCD-HEMT) has been proposed and fabricated. The FCD-HEMT features the field control drain (FCD), consisting of electrically shorted Ohmic contact structure and p-GaN cap. In the OFF-state, the 2-Dimensional Electron Gas (2DEG) channel is cut off due to the p-GaN cap introduced field control, which provides FCD-HEMT with reverse blocking capability. In the ON-state, the re-formed 2DEG channel offers a non-potential barrier pathway for electrons transfer from source to drain and ensures a low resistance of the FCD-HEMT. The fabricated device exhibits 1400 V forward breakdown voltage (BV F) and −1240 V reverse breakdown voltage (BV R), 12.7 mΩ·cm2 low specific ON-resistance, and 188 mA mm−1 max drain current while maintaining normally-OFF capability. These results demonstrate the great potential of FCD-HEMTs in 1200 V-class power applications.

Optimization of Schottky-contact process on 4H-SiC Junction Barrier Schottky (JBS) Diodes

SiC Junction Barrier Schottky (JBS) Rectifier is a kind of unipolar power diode with low threshold voltage and high reverse blocking voltage. And the Schottky barrier Φ BN is a main technology parameter, which could greatly affect the forward conduction power and reverse leakage current in the JBS rectifiers. Therefore, it is necessary to balance the influence of Φ BN on the electrical characteristics of JBS rectifiers. In this paper, physical properties at the metal-semiconductor at the Schottky-contact could be optimized by the improvement of Schottky-contact process. And this optimization could significantly decrease Φ BN to reduce the on-state voltage drop V F and minimize negative impact on its reverse characteristics. After the completion of Silicon carbide JBS diodes, the static parameter electrical test was carried out on the wafer by using Keysight B1505A Power Device Analyzer/Curve Tracer. The test results show that the Schottky barrier height Φ BN of JBS Schottky rectifier manufactured by the modified Schottky foundation technology decreased from 1.19eV to 0.99eV and I R increased from 1.08μA to 3.73μA (reverse blocking voltage V R=1200V). It indicated that the power consumption of Schottky barrier junction in JBS rectifiers could be significantly reduced by about 25%, and I R could effectively be limited to less than 10μA.

Demonstration of a 2 kV Al0.85Ga0.15N Schottky Barrier Diode With Improved On-Current and Ideality Factor

In this letter, we report on demonstrating a Schottky barrier diode (SBD) with high reverse blocking voltage by incorporating an ultra-wide bandgap semiconductor Al0.85 Ga0.15 N channel. Benefited from the lower activation energy of the Si in GaN, the net carrier concentration of Al0.85 Ga0.15N can be essentially enhanced to ${2}\times {10}^{{17}}$ cm−3 level with surface roughness of 0.33 nm. Due to the good material property, a reverse blocking voltage of 2 kV and room temperature ideality factor of 2.3 are demonstrated. Combined with the significantly improved on-current and on/off ratio of more than 106 when compared with other AlN SBDs, Al0.85 Ga0.15 N turns out to be a competitive AlN counterpart by considering the compromise among ultra-wide bandgap, dopant activation, and material property.

Field-Plated Lateral β-Ga2O3 Schottky Barrier Diode with High Reverse Blocking Voltage of More Than 3 kV and High DC Power Figure-of-Merit of 500 MW/cm2

In this letter, we report on demonstrating high-performance field-plated lateral <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Schottky barrier diode (SBD) on a sapphire substrate with a reverse blocking voltage of more than 3 kV and a low dc specific ON-resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{{ \mathrm{\scriptscriptstyle ON}, \text {sp}}}$ </tex-math></inline-formula> ) of 24.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at an anode–cathode spacing ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {AC}}$ </tex-math></inline-formula> ) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$24~\mu \text{m}$ </tex-math></inline-formula> . To the best of our knowledge, this lateral breakdown voltage (BV) >3 kV with dc power figure-of-merit (FOM) >370 MW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is the highest BV achieved among all the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> SBDs. Meanwhile, lateral <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> SBD with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {AC}} = \text {16}\,\,\mu \text{m}$ </tex-math></inline-formula> also demonstrates a high BV of 2.25 kV and low <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{{ \mathrm{\scriptscriptstyle ON}, \text {sp}}} = \text {10.2}\,\,\text{m}\Omega \cdot $ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , yielding a record high dc power FOM of 500 MW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Combining with 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> high-current ON/OFF ratio, 1.15-eV Schottky barrier height and 1.25 ideality factor, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> SBD with field-plate structure shows its great promise for power electronics applications.

A Multiple-Ring-Modulated JTE Technique for 4H-SiC Power Device With Improved JTE-Dose Window

In this paper, a multiple-ring-modulated junction termination extension (MRM-JTE) technology for large-area silicon carbide PiN rectifier rated at 4500 V is proposed and experimentally investigated using a standard two-zone JTE (TZ-JTE) process without extra process steps or masks. Multiple modulation rings embedded inside JTE region, which is similar to varied lateral doping technology widely used in silicon devices, form a gradual decrease of effective charges in the termination region. MRM combines the advantages of two termination techniques, namely, ring-assisted JTE and space-modulated JTE, to enlarge the optimum JTE-dose window with high reverse blocking voltage in comparison with conventional TZ-JTE. A breakdown voltage of 4940 V at a leakage current of $1~\mu \text{A}$ is achieved from fabricated MRM-JTE rectifiers with a 36- $\mu \text{m}$ -thick N− epilayer doped to ${1.8} \times {10}^{{15}}$ cm−3, which is 92% of the ideal parallel-plane value. A forward current of 50 A has been measured at a forward voltage drop of 3.9 V for devices with an active anode area of 9.2 mm2, corresponding to low differential on-resistance of 1.8 $\text{m}\Omega \cdot \text {cm}^{ {2}}$ . The simulation and experimental results show that the proposed device exhibits approximately 2 times JTE dose tolerance window improvement with respect to the breakdown voltage of 4500 V.

On the Use of Front-End Cascode Rectifiers Based on Normally On SiC JFET and Si MOSFET

The new wide band-gap semiconductor devices provide new properties to be explored. Normally on silicon carbide (SiC) JFET power devices have several advantages, in particular low switching losses and the potential capabilities of high temperature and high reverse blocking voltage. Looking for improving the overall efficiency in power converters, new structures based on these power devices might be studied. In this paper, a cascode rectifier based on normally on SiC JFET is presented and analyzed. This rectification structure can be applied as front-end rectifier stage for ac-dc power converters, increasing the overall efficiency of these topologies. A second cascode rectifier based on silicon (Si) MOSFET is also studied, as a low-cost alternative. A simple static forward characterization and a brief dynamic behavior analysis of the proposed cascode rectifier structure are made. Both cascode structures are compared with traditional Si rectifier diodes and front-end rectifiers, using an active power factor corrector (PFC) interleaved boost converter. As a result of this comparison, an efficiency improvement as high as two points is obtained. An additional OR gate based on a diode is also used as second test circuit to compare the proposed structures to the traditional Si rectifiers. A reduction between 75% and 55% of the total loss are obtained in this second experimental test.

Analysis and Optimization of a Thyristor Structure Using Backside Schottky Contacts Suited for the High Temperature

In high current, high voltage, high temperature power applications, commercially available conventional silicon thyristors are not suited because they present high leakage current. In this context, this paper presents a high-symmetrical (voltage) thyristor structure that presents a lower leakage current and higher breakover voltage as compared with the conventional thyristor at. It is shown through 2-D physical simulations that the replacement of the P-emitter of a standard symmetrical thyristor by a judicious association of P diffusions and Schottky contacts at the anode side contributes to the reduction of the leakage current in the forward blocking state at high temperature. A fine tune of the anode side configuration will improve the forward OFF-state behavior with only a negligible ON-state voltage drop degradation. Moreover, the comparison with the conventional anode short thyristor shows that the insertion of Schottky contacts leads to the same improvements in terms of OFF-state forward breakover voltage and leakage current and also presents a high reverse blocking voltage.

High current characteristics of asymmetrical p-i-n diodes having low forward voltage drops

A closed form solution for the forward characteristics of a very asymmetrical step-junction p-i-n diode at high current levels is derived and discussed. It is found that the forward voltage decreases significantly when the amount of the impurities per unit area of one of the highly doped regions is reduced. The theory is confirmed by experiment, and the diodes obtained show a low forward loss together with high reverse blocking voltage and fast reverse recovery.