IEEE Power Electronics Magazine - March 2015 - 32

in 1-, 5-, and 20-A current ratings
area of the p+ implanted region, and
feature reverse leakage currents
layout of the p+ implanted region.
The FN current can be
of <3 mA/cm 2 at 1,200 V up to temThe larger the relative area of the
assumed to be
p+ implanted region, the higher the
peratures as high as 300 °C. GeneSiC's 1,200-V/20-A high-temperature
on -state voltage drop is (because of
proportional to the
Schottky (designated SHT) rectifier
smaller conducting area) and the
square of the
offers a 10# reduction in leakage
lower the leakage current of the
current and a 23% reduction in juncdiode is. Since a deep p+ implant is
temperature.
tion capacitance when compared
more effective in pinching off the
with its nearest SiC Schottky rectileakage current, it is expected to
fier competitor. In addition, these
result in lower leakage current in
SHT rectifiers demonstrate superior surge-current ratthe diode. However, this may also result in a confined
ings and temperature-independent switching capability
on -current flow, resulting in a higher voltage drop in the
+
up to their rated junction temperatures.
on -state. In addition, a deep p implant results in a more
Device designs and fabrication processes were develdamaged implanted region, which may cause enhanced
oped at GeneSiC to enable the SiC SHT rectifiers to block
leakage currents.
their rated voltage, even at temperatures as high as 300 °C
with low leakage currents. The topmost metallization for
High-Temperature SiC Power Devices
these SHT rectifiers is formed by either thick aluminum
The electrical characteristics of industry's first com(Al) or gold (Au) to be compatible with wire-bonded or
mercially available 1,200-V-rated SiC Schottky rectififully soldered packaging, respectively. The 1,200-V SHT
ers specially designed for operation at $250 °C are prerectifiers were fabricated with three different chip sizes
sented. These high-temperature SiC rectifiers fabricated
corresponding to 1- , 5- , and 20-A chip current ratings.
When these chips are packaged in different packages
with different thermal characteristics, they offer correspondingly different current ratings. These devices are
packaged in industry-standard two-leaded TO-46, three3
1
leaded TO-257, and surface-mount (SMB05/TO-276) packages, as shown in Figure 4.
Although these packages and the associated solders
(a)
(b)
(c)
and encapsulations were rated for <250 oC junction temperatures, these devices were electrically characterized
fig 4 The small-form-factor (a) two-leaded TO-46, (b) isolated
up to 300 °C and offered in bare die form using Au as the
TO-257, and (c) surface-mount SMB05 (TO-276) packages were
topside metal. Very low leakage currents are measured on
used for the packaging of high-temperature SiC rectifiers. Similar
a 1,200-V/1-A SiC SHT rectifier up to 300 °C (Figure 5). A
three-leaded packages are also used in the offerings with hightemperature SJTs.
clear signature of avalanche limited breakdown can be

30
20

500
400
300

200

100

0
0

400

800

1,200

1,600

Reverse Bias (V)
fig 5 The reverse blocking I-V characteristics of a 1,200-V/1-A
SiC Schottky rectifier up to 300 °C ambient temperature.

25 °C
75 °C
125 °C
175 °C
225 °C

8
Current (A)

40
Current (nA)

25 °C
125 °C
175 °C
225 °C
275 °C
300 °C

IEEE PowEr ElEctronIcs MagazInE

z March 2015

Current Density (A/cm2)

0
0

Forward Bias (V)
fig 6 The ambient temperature-dependent on-state characteristics measured on a 1,200-V/5-A SiC SHT Rectifier.

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - March 2015