Development of SiC Super-Junction (SJ) Devices by Multi-Epitaxial Growth

2014 ◽  
Vol 778-780 ◽  
pp. 845-850 ◽  
Author(s):  
Ryoji Kosugi ◽  
Yuuki Sakuma ◽  
Kazutoshi Kojima ◽  
Sachiko Itoh ◽  
Akiyo Nagata ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Device Simulation ◽  
Specific Resistivity ◽  
Power Devices ◽  
Theoretical Limit ◽  
Beneficial Effects ◽  
Blocking Voltage ◽  
First Time ◽  
Unipolar Devices ◽  
Drift Layer

Super-junction (SJ) devices have been developed to improve the trade-off relationship between the blocking voltage (VBD) and specific on-resistance in unipolar power devices. This SJ structure effect is expected in SiC unipolar devices. Multi-epitaxial growth is a known fabrication method for SJ structures where epitaxial growth and ion implantation are repeated alternately until a certain drift-layer thickness is achieved. In this study, we fabricated two types of test elemental groups with an SJ structure to evaluate the breakdown voltage (VBD) and specific resistivity of the drift layer (Rdrift). Experimental results show that VBDexceeded the theoretical limit of the 4H-SiC by 300V, and Rdriftagreed well with the estimated value from the device simulation. The beneficial effects of the SJ structure in the SiC material on VBDand Rdriftwere confirmed for the first time.

Rapid Epitaxial Growth of Si and SiGe Mono-Crystalline Films on Silicon-on-Glass Substrates by Reactive CVD Using SiH4, GeH4, and F2

2012 ◽  
Vol 1426 ◽  
pp. 331-337
Author(s):  
Hiroshi Noge ◽  
Akira Okada ◽  
Ta-Ko Chuang ◽  
J. Greg Couillard ◽  
Michio Kondo
Keyword(s):  
Epitaxial Growth ◽  
Heating Temperature ◽  
Exothermic Reaction ◽  
Epitaxial Films ◽  
Si Substrates ◽  
Glass Substrates ◽  
Good Crystallinity ◽  
Crystalline Films ◽  
Si Films ◽  
First Time

ABSTRACTWe have succeeded in the rapid epitaxial growth of Si, Ge, and SiGe films on Si substrates below 670 ºC by reactive CVD utilizing the spontaneous exothermic reaction between SiH4, GeH4, and F2. Mono-crystalline SiGe epitaxial films with Ge composition ranging from 0.1 to 1.0 have been successfully grown by reactive CVD for the first time.This technique has also been successfully applied to the growth of these films on silicon-on-glass substrates by a 20 - 50 ºC increase of the heating temperature. Over 10 μm thick epitaxial films at 3 nm/s growth rate are obtained. The etch pit density of the 5.2 μm-thick Si0.5Ge0.5 film is as low as 5 x 106 cm-2 on top. Mobilities of the undoped SiGe and Si films are 180 to 550 cm2/Vs, confirming the good crystallinity of the epitaxial films.

scholarly journals The Dose of Somatostatin Analogues during Pre-Surgical Treatment Is a Key Factor to Achieve Surgical Remission in Acromegaly

Endocrines ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 241-250
Author(s):  
Marta Araujo-Castro ◽  
Eider Pascual-Corrales ◽  
Héctor Pian ◽  
Ignacio Ruz-Caracuel ◽  
Alberto Acitores Cancela ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Surgical Treatment ◽  
Surgical Outcomes ◽  
Pituitary Adenomas ◽  
Somatostatin Analogues ◽  
Beneficial Effects ◽  
Key Factor ◽  
Long Acting ◽  
First Time ◽  
Endocrine Complications

Purpose: to determine whether pre-surgical treatment using long-acting somatostatin analogues (SSAs) may improve surgical outcomes in acromegaly. Methods: retrospective study of 48 patients with acromegaly operated by endoscopic transsphenoidal approach and for first time. Surgical remission was evaluated based on the 2010 criteria. Results: most patients, 83.3% (n = 40), harbored macroadenomas and 31.3% (n = 15) invasive pituitary adenomas. In this case, 14 patients were treated with lanreotide LAR and 6 with octreotide LAR, median monthly doses of 97.5 [range 60–120] and 20 [range 20–30] mg, respectively, for at least 3 months preoperatively. Presurgical variables were comparable between pre-treated and untreated patients (p > 0.05). Surgical remission was more frequent in those pre-treated with monthly doses ≥90 mg of lanreotide or ≥30 mg of octreotide than in untreated or pre-treated with lower doses (OR = 4.64, p = 0.025). However, no differences were found between pre-treated and untreated patients when lower doses were included or between those treated for longer than 6 months compared to those untreated or pre-treated for shorter than 6 months. Similarly, no differences were found either in terms of surgical or endocrine complications (OR = 0.65, p = 0.570), independently of the doses and the duration of SSA treatment (p > 0.05). Conclusions: the dose of SSAs is a key factor during pre-surgical treatment, since the beneficial effects in surgical remission were observed with monthly doses equal or higher than 90 mg of lanreotide and 30 mg of octreotide, but not with lower doses.

scholarly journals AZP2006, a new promising treatment for Alzheimer’s and related diseases

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
N. Callizot ◽  
C. Estrella ◽  
S. Burlet ◽  
A. Henriques ◽  
C. Brantis ◽  
...  
Keyword(s):  
Therapeutic Application ◽  
Neuroprotective Effects ◽  
Beneficial Effects ◽  
Potential Therapeutic Application ◽  
Promising Treatment ◽  
Central Synapses ◽  
First Time ◽  
Pgrn Level

AbstractProgranulin (PGRN) is a protein with multiple functions including the regulation of neuroinflammation, neuronal survival, neurite and synapsis growth. Although the mechanisms of action of PGRN are currently unknown, its potential therapeutic application in treating neurodegenerative diseases is huge. Thus, strategies to increase PGRN levels in patients could provide an effective treatment. In the present study, we investigated the effects of AZP2006, a lysotropic molecule now in phase 2a clinical trial in Progressive Supranuclear Palsy patients, for its ability to increase PGRN level and promote neuroprotection. We showed for the first time the in vitro and in vivo neuroprotective effects of AZP2006 in neurons injured with Aβ1–42 and in two different pathological animal models of Alzheimer’s disease (AD) and aging. Thus, the chronic treatment with AZP2006 was shown to reduce the loss of central synapses and neurons but also to dramatically decrease the massive neuroinflammation associated with the animal pathology. A deeper investigation showed that the beneficial effects of AZP2006 were associated with PGRN production. Also, AZP2006 binds to PSAP (the cofactor of PGRN) and inhibits TLR9 receptors normally responsible for proinflammation when activated. Altogether, these results showed the high potential of AZP2006 as a new putative treatment for AD and related diseases.

12 kV 4H-SiC p-IGBTs with Record Low Specific On-Resistance

2008 ◽  
Vol 600-603 ◽  
pp. 1187-1190 ◽  
Author(s):  
Q. Jon Zhang ◽  
Charlotte Jonas ◽  
Joseph J. Sumakeris ◽  
Anant K. Agarwal ◽  
John W. Palmour
Keyword(s):  
Carrier Lifetime ◽  
Drift Region ◽  
Gate Bias ◽  
Enhancement Layer ◽  
Channel Mobility ◽  
Dc Characteristics ◽  
Blocking Voltage ◽  
High Carrier ◽  
P Type ◽  
First Time

DC characteristics of 4H-SiC p-channel IGBTs capable of blocking -12 kV and conducting -0.4 A (-100 A/cm2) at a forward voltage of -5.2 V at 25°C are demonstrated for the first time. A record low differential on-resistance of 14 mW×cm2 was achieved with a gate bias of -20 V indicating a strong conductivity modulation in the p-type drift region. A moderately doped current enhancement layer grown on the lightly doped drift layer effectively reduces the JFET resistance while maintains a high carrier lifetime for conductivity modulation. A hole MOS channel mobility of 12.5 cm2/V-s at -20 V of gate bias was measured with a MOS threshold voltage of -5.8 V. The blocking voltage of -12 kV was achieved by Junction Termination Extension (JTE).

Comparison of Bipolar and Unipolar SiC Switching Devices for Very High Power Applications

2007 ◽  
Vol 556-557 ◽  
pp. 975-978
Author(s):  
Kent Bertilsson ◽  
Chris I. Harris
Keyword(s):  
Field Effect ◽  
Field Effect Transistor ◽  
Static Case ◽  
Simulation Studies ◽  
Drift Diffusion ◽  
Element Approach ◽  
Effect Transistor ◽  
Unipolar Devices ◽  
Very High ◽  
Drift Layer

Both unipolar and injection SiC devices can be used for high voltage switching applications; it is not determined, however, for which applications one approach is preferred over the other. In this paper, simulation studies are used to compare the suitability of unipolar devices, in this case a JFET (Junction Field Effect Transistor) against an equivalent FCD (Field Controlled Diode) configuration up to very high voltages. The calculations are performed in a finite element approach, with commercial drift-diffusion software. Numerous drift layers have been simulated in a Monte-Carlo approach to ensure that the optimal design of the drift layers for different breakdown is used. In a static case, purely conductive losses in the drift layer in both unipolar and injection configuration are compared. Additionally the total losses are studied and compared in switched applications for different switching frequencies and current levels.

20 kV 4H-SiC N-IGBTs

2014 ◽  
Vol 778-780 ◽  
pp. 1030-1033 ◽  
Author(s):  
Sei Hyung Ryu ◽  
Craig Capell ◽  
Charlotte Jonas ◽  
Michael J. O'Loughlin ◽  
Jack Clayton ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Leakage Current ◽  
Supply Voltage ◽  
Boost Converter ◽  
Power Switching ◽  
Switching Device ◽  
Blocking Voltage ◽  
Off Time ◽  
Drift Layer ◽  
Stop Buffer

A 1 cm x 1 cm 4H-SiC N-IGBT exhibited a blocking voltage of 20.7 kV with a leakage current of 140 μA, which represents the highest blocking voltage reported from a semiconductor power switching device to this date. The device used a 160 μm thick drift layer and a 1 μm thick Field-Stop buffer layer, and showed a VF of 6.4 V at an IC of 20 A, and a differential Ron,sp of 28 mΩ-cm2. Switching measurements with a supply voltage of 8 kV were performed, and a turn-off time of 1.1 μs and turn-off losses of 10.9 mJ were measured at 25°C, for a 8.4 mm x 8.4 mm device with 140 μm drift layer and 2 μm F-S buffer layer. The turn-off losses were reduced by approximately 50% by using a 5 μm F-S buffer layer. A 55 kW, 1.7 kV to 7 kV boost converter operating at 5 kHz was demonstrated using the 4H-SiC N-IGBT, and an efficiency value of 97.8% was reported.

4H-SIC Dmosfets for High Frequency Power Switching Applications

2003 ◽  
Vol 764 ◽  
Author(s):  
Sei-Hyung Ryu ◽  
Anant K. Agarwal ◽  
James Richmond ◽  
John W. Palmour
Keyword(s):  
High Voltage ◽  
High Speed ◽  
High Performance ◽  
High Frequency Power ◽  
Power Devices ◽  
Power Switching ◽  
High Speed Switching ◽  
Unipolar Devices ◽  
Very High ◽  
Frequency Power

AbstractVery high critical field, reasonable bulk electron mobility, and high thermal conductivity make 4H-Silicon carbide very attractive for high voltage power devices. These advantages make high performance unipolar switching devices with blocking voltages greater than 1 kV possible in 4H-SiC. Several exploratory devices, such as vertical MOSFETs and JFETs, have been reported in SiC. However, most of the previous works were focused on high voltage aspects of the devices, and the high speed switching aspects of the SiC unipolar devices were largely neglected. In this paper, we report on the static and dynamic characteristics of our 4H-SiC DMOSFETs. A simple model of the on-state characteristics of 4H-SiC DMOSFETs is also presented.

Impact of Cell Layout and Device Structure on On-Voltage Reduction of 6.5-kV n-Channel SiC IGBTs

2018 ◽  
Vol 924 ◽  
pp. 637-640 ◽  
Author(s):  
Naoki Watanabe ◽  
Hiroyuki Yoshimoto ◽  
Akio Shima
Keyword(s):  
Potential Barrier ◽  
Device Simulation ◽  
Electron Injection ◽  
Channel Width ◽  
Barrier Structure ◽  
Collector Current ◽  
Device Structure ◽  
Conventional Structure ◽  
Low Drift ◽  
Drift Layer

A box cell layout and a hole-barrier structure were used to realize low-on-voltage n-channel 4H-SiC IGBTs with 6.5-kV blocking capability. Box cell layout can increase the channel width, leading to reduction of the channel resistance and an enhancement of electron injection from an emitter. Hole-barrier structure, which is a potential barrier for holes to prevent them from flowing out of the emitter, can enhance conductivity modulation. An on-voltage of 3.98 V at a collector current of 100 A/cm2 was achieved from a fabricated SiC IGBTin this study. Since the on-voltage of a SiC IGBT with a conventional structure was 4.81 V at the same collector current, the effect of our new structure was successfully shown to reduce the on-voltage of SiC IGBTs. An estimation of each voltage component involved in the on-voltage was also carried out by utilizing a device simulation, and the estimation shows that a SiC IGBT incorporating a box layout and hole-barrier structure will thus have quite a low drift-layer voltage and an on-voltage close to the limit determined by the bipolar built-in voltage.

4H-SiC Homoepitaxial Growth on Vicinal-Off Angled Si-Face Substrate

2010 ◽  
Vol 645-648 ◽  
pp. 99-102 ◽  
Author(s):  
Kazutoshi Kojima ◽  
Sachiko Ito ◽  
Junji Senzaki ◽  
Hajime Okumura
Keyword(s):  
Surface Morphology ◽  
Epitaxial Growth ◽  
Growth Temperature ◽  
Growth Conditions ◽  
Step Bunching ◽  
Homoepitaxial Growth ◽  
Blocking Voltage ◽  
Basal Plane Dislocation ◽  
Epilayer Surface

We have carried out detailed investigations of 4H-SiC homoepitaxial growth on vicinal off-angled Si-face substrates. We found that the surface morphology of the substrate just after in-situ H2 etching was also affected by the value of the vicinal-off angle. Growth conditions consisting of a low C/Si ratio and a low growth temperature were effective in suppressing macro step bunching at the grown epilayer surface. We also demonstrated epitaxial growth without step bunching on a 2-inch 4H-SiC Si-face substrate with a vicinal off angle of 0.79o. Ni Schottky barrier diodes fabricated on an as-grown epilayer had a blocking voltage above 1000V and a leakage current of less than 5x10-7A/cm2. We also investigated the propagation of basal plane dislocation from the vicinal off angled substrate into the epitaxial layer.

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