Effect of Bipolar Gate-to-Drain Current on the Electrical Properties of Vertical Junction Field Effect Transistors

Veliadis, Victor; Hearne, Harold; Stewart, Eric J.; Caldwell, Joshua D.; Snook, Megan; McNutt, Ty; Potyraj, Paul; Scozzie, Charles

doi:10.4028/www.scientific.net/msf.615-617.719

Cited by 11 publications

(11 citation statements)

References 10 publications

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“…Under bipolar gate-to-drain current flow, electron -hole pair recombination at basal-plane-dislocations (BPDs) in the drift layer of the VJFET induces stacking fault formation and expansion [42,43], which causes significant degradation in the electrical characteristics of SiC power p -n diodes and DMOSFETs with thick drift epitaxial layers [5,44]. To assess the reliability of cascode-switch power conditioning with no external diodes present, the effect of bipolar gate-to-drain current on the electrical characteristics of 1200 V vertical-channel JFETs with 12 μm drift epitaxial layers was investigated [45]. The VJFETs were grown on substrates in which the density of BPDs was not suppressed during epitaxial growth.…”

Section: Reliability Of the 1200 V Normally-off All-sic Vjfet Cascodementioning

confidence: 99%

“…No further on-state drain current degradation was observed after an additional 495 hours of gate-to-drain stressing. In addition, performing multiple 350 °C annealing cycles (identical to those that recovered degradations in 100 μm drift layer VJFETs [45]) had no measurable impact on the post-stress on-state drain current characteristics. Thus, the observed post-stress, on-state drain-current degradation is attributed to a "burn-in" effect.…”

Section: Figure 18mentioning

confidence: 99%

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1200 V SiC vertical‐channel‐JFETs and cascode switches

Veliadis

2009

Physica Status Solidi (a)

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Wide band gap semiconductors like silicon carbide (SiC) are currently being developed for high power/temperature applications. Silicon carbide is ideally suited for power switching due to its high saturated drift velocity, its high critical field strength, its excellent thermal conductivity, and its mechanical strength. For power devices, the tenfold increase in critical field strength of SiC relative to Si allows high voltage blocking layers to be fabricated significantly thinner than those of comparable Si devices. This reduces device on‐state resistance and the associated conduction and switching losses, while maintaining the same high voltage blocking capability. The specific on‐state resistance of 4H‐SiC is approximately 400 times lower than that of Si at a given breakdown voltage. This allows for high current operation at relatively low forward voltage drop. In addition, the wide band gap of SiC allows operation at high temperatures where conventional Si devices fail. In this article, we will review Northrop Grumman's single‐implant no‐epitaxial‐regrowth vertical‐channel JFET. The feasibility of efficient 1200 V normally‐off VJFET operation will be investigated. The all‐SiC VJFET based cascode switch will be introduced and aspects of its operation evaluated. High temperature DC characteristics of VJFETs and 1200 V normally‐off cascode switches will be discussed. Finally, the development of large‐area high‐current 1200 V VJFETs and their edge termination performance will be presented. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Reliability Of the 1200 V Normally-off All-sic Vjfet Cascodementioning

confidence: 99%

Section: Figure 18mentioning

confidence: 99%

1200 V SiC vertical‐channel‐JFETs and cascode switches

Veliadis

2009

Physica Status Solidi (a)

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“…There has been some recent success at limiting BPD densities during epitaxial growth by leveraging the aforementioned BPD 'turning' phenomenon, [10][11][12][13] however, their density still remains appreciable and therefore over time, SF-induced device degradation still occurs. Furthermore, it has also been reported that this degradation is not limited strictly to bipolar devices, but also adversely affects unipolar devices such as DMOSFETs, 14,15 VJFETs, 16 and MPS diodes 14 where bipolar injection into the active area of the device is possible.…”

Section: Introductionmentioning

confidence: 99%

On the Driving Force of Shockley Stacking Fault Motion in 4H-SiC

et al. 2009

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Determining the primary driving force for Shockley stacking fault (SF) expansion within 4H-SiC has been of intense interest due to the deleterious effects of these defects upon the electrical characteristics of bipolar SiC devices. Previoulsy reported models have focused on determining the reasons for the perceived improved thermodynamic stability of the SFs, which are planes of SiC with the 3C-SiC polytype, with respect to the 4H-SiC host lattice. However, annealing and high temperature device operation experiments have clearly shown that SFs are not the thermodynamically preferred state of 4H-SiC in the absence of excess injected carriers. Here, we introduce and discuss a possible mechanism governing SF expansion and contraction that is consistent with previously reported experimental observations and present further experimental and simulation results that support this model.

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“…In addition, the minority carrier recombination in bipolar operation reduces switching speeds, which increases switching losses. Finally, bipolar recombination at basal-plane dislocations in the thick drift layers of ∼10-kV VJFETs induces stacking fault formation and expansion, which can cause forward-voltage degradation [15]. Therefore, high-current-gain operation at a low unipolar (gate biased below its built-in potential) ON-state resistance is required for efficient and reliable VJFET power switching.…”

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A 9-kV Normally-on Vertical-Channel SiC JFET for Unipolar Operation

Veliadis

Stewart

Hearne

et al. 2010

IEEE Electron Device Lett.

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A normally-ON 9-kV (at 0.1-mA/cm 2 drain leakage) 1.52 × 10 −3 -cm 2 active-area vertical-channel SiC JFET (VJFET) is fabricated with no e-beam lithography, no epitaxial regrowth, and a three-step junction-termination-extension edge termination, which is connected to the gate bus through an ion-implanted sloped extension. The VJFET exhibits low leakage currents and a sharp onset of gate-voltage breakdown occurring at 80 V. To lower resistance, the VJFET is designed to be very normally-ON, which minimizes the channel resistance contribution. At a gate bias of 0 V, the VJFET's drain current is 73 mA with a forward drain voltage drop of 5 V (240 W/cm 2 ), a specific ON-state resistance of 104 mΩ · cm 2 , and a current gain of I D /I G = 6.4 × 10 6 . Operating at a unipolar gate bias of 2.5 V lowers the ON-state resistance to 96 mΩ · cm 2 and raises the drain-current output to 79.3 mA, with the current gain being relatively high at I D /I G = 2346. Thus, this 9-kV VJFET is capable of efficient power switching operation with high current gain at a low unipolar resistance.

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Effect of Bipolar Gate-to-Drain Current on the Electrical Properties of Vertical Junction Field Effect Transistors

Cited by 11 publications

References 10 publications

1200 V SiC vertical‐channel‐JFETs and cascode switches

1200 V SiC vertical‐channel‐JFETs and cascode switches

On the Driving Force of Shockley Stacking Fault Motion in 4H-SiC

A 9-kV Normally-on Vertical-Channel SiC JFET for Unipolar Operation

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