IEEE Power Electronics Magazine - March 2015 - 35

600

5

200

0

0
0

50

100
Time, t (ns)

150

200

1,000

8

800

6
4

s

tr = 12
ns

400

1,200

2

RG (on) = 22 X
VGS = -8/15 V
250 °C
25 °C

600
400
200

0

Drain-Source Voltage (V)

800

10

Drain Current (A)

10

1,000
Drain-Source Voltage (V)

RG (on) = 22 X
VGS = -8/15 V
250 °C
25 °C

t f = 13 n

Drain Current (A)

15

0
0

50

(a)

100
Time, t (ns)

150

200

(b)

fig 12 The (a) turn-on and (b) turn-off drain current and voltage transients recorded for switching 800 V and 8 A through a 4-mm2 SiC
SJT. There is no difference in switching speed between 25 and 250 °C, due to the unipolar nature of the SJT device design.

switching performance. Temperature-independent, ultralow drain current rise and fall times of 12 and 13 ns, respectively, were recorded (Figure 12) for switching 8 A and
800 V by the 4-mm2 SJT.

excellent robustness and reliability at high temperatures
and are expected to dominate the high-temperature switching applications.

About the Authors
Conclusions
In this article, the fundamental physical phenomena that
determine the high-temperature operation of SiC power
devices have been outlined. It has been shown that the
metal-semiconductor barrier height plays a critical role in
determining the high-temperature leakage currents, and
pure Schottky diodes are not expected to have significantly
lower leakage currents as compared with Si p-i-n diodes.
However, using the JBS device structures, leakage currents
can be designed to be more dependent on the p-n junction,
utilizing the wide bandgap of SiC. Commercial, high-temperature packaged devices have been demonstrated to show
good leakage current performance even up to 300 oC. The
physical phenomena determining the fundamental electron
tunneling probabilities in MOS structures show that the tunneling probabilities for MOS structures is higher in SiC as
compared with Si MOS structures. This implies that the
high-temperature reliability due to electron tunneling is
expected to be poorer in SiC MOS structures as compared
with Si MOS structures at all operating temperatures. An
SiC junction transistor relies on purely junction-based forward conduction and blocking characteristics and, thus, has
been demonstrated to show low leakage currents even at
high temperatures. SJTs with low leakage currents even at
325 oC are demonstrated. Further, SJTs offer field-effecttransistor-like on-state characteristics with positive temperature coefficient of on-resistance, temperature-independent
sub-15-ns turn-on and turn-off characteristics, and a square
reverse-bias safe operating area. These devices also offer

Ranbir Singh (Ranbir.singh@genesicsemi.com) is the
president and chief executive officer at GeneSiC Semiconductor Inc., Dulles, Virginia.
Siddarth Sundaresan (siddarth.sundaresan@genesicsemi.com) is with GeneSiC Semiconductor Inc., Dulles,
Virginia.

References
[1] P. G. Neudeck, "Electrical impact of SiC structural crystal defects
on high electric field devices," Materials Sci. Forum, vols. 338-342,
pp. 1161-1166, 2000.
[2] T. Kimoto, N. Miyamoto, and H. Matsunami, "Performance limiting surface defects in SiC epitaxial layers p-n junction diodes," IEEE Trans. Electron Devices, vol. 46, no. 3, pp. 471-477, 1999.
[3] P. G. Neudeck, W. Huang, and M. Dudley, "Study of bulk and elementary screw dislocation assisted reverse breakdown in low-voltage (<250 V)
4H-SiC P+N junction diodes-Part I: DC properties," IEEE Trans. Electron
Devices, vol. 46, no. 3, pp. 478-484, 1999.
[4] S. M. Sze, Physics of Semiconductor Devices. New York: Wiley, 1981.
[5] M. Bhatnagar, B. J. Baliga, H. R. Kirk, and G. A. Rozgonyi, "Effect of
surface inhomogeneities on the electrical characteristics of SiC Schottky
contacts," IEEE Trans. Electron Devices, vol. 43, no. 1, pp. 150-156, 1996.
[6] J. Crofton and S. Sriram, "Reverse leakage current calculations for
SiC Schottky contacts," IEEE Trans. Electron Devices, vol. 43, no. 12, pp.
2305-2307, 1996.
[7] G. Pananakakis, G. Ghibaudo, and R. Kies, "Temperature dependence of
the Fowler-Nordheim current in metal-oxide-degenerate structures," J. Appl.
Phy., vol. 78, no. 4, pp. 2635-2641, 1995.
[8] [Online]. Available: http://public.itrs.net/

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