In this summary, we have shown that diodes are susceptible to destructive single-event effects, and that these failures occur along the guard ring. By determining the last passing voltages, a safe operating area can be derived. By derating off of those values, rather than by the rated voltage, like what is currently done with power MOSFETs, we can work to ensure the safety of future missions. However, there are still open questions about these failures. Are they limited to a single manufacturer, a small number, or all of them? Is there a threshold rated voltage that must be exceeded to see these failures? With future work, we hope to answer these questions. In the full paper, laser results will also be presented to verify that failures only occur along the guard ring

Casey, Megan C.

Chen, Dakai

Gigliuto, Robert A.

Kim, Hak

LaBel, Kenneth A.

Lauenstein, Jean-Marie

Phan, Anthony M.

Wilcox, Edward P.

NASA Technical Reports Server

To be presented by Megan C. Casey at the Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Space 
Radiation Effects Conference (NSREC), July 8-12, 2013, San Francisco, California. 
 
 1 
 
Abstract—We examine single-event induced destructive failures in Schottky diodes.  We first identified failures in DC-DC 
converters, and later confirmed their existence in independent diodes.  The mechanism for failure along guard rings is also 
discussed. 
 
 
Corresponding Author: 
Megan C. Casey, NASA Goddard Space Flight Center (GSFC), Code 561.4, Greenbelt, MD 20771 (USA), phone: 301-286-1151,  
fax: 301-286-4699, e-mail: megan.c.casey@nasa.gov 
 
Contributing Authors: 
Robert A. Gigliuto, MEI Technologies, Inc., c/o NASA Goddard Space Flight Center (GSFC), Code 561.4, Bldg. 22, Rm. 052,  
Greenbelt, MD 20771 (USA), phone: 301-286-3327, fax: 301-286-4699, e-mail: robert.a.gigliuto@nasa.gov 
Jean-Marie Lauenstein, NASA Goddard Space Flight Center (GSFC), Code 561.4, Greenbelt, MD 20771 (USA), phone: 301-286-5587,  
fax: 301-286-4699, e-mail: jean.m.lauenstein@nasa.gov 
Edward P. Wilcox, MEI Technologies, Inc., c/o NASA Goddard Space Flight Center (GSFC), Code 561.4, Bldg. 22, Rm. 080,  
Greenbelt, MD 20771 (USA), phone: 301-286-5450, fax: 301-286-4699, e-mail: ted.wilcox@nasa.gov 
Hak S. Kim, MEI Technologies, Inc., c/o NASA Goddard Space Flight Center (GSFC), Code 561.4, Bldg. 22, Rm. 056,  
Greenbelt, MD 20771 (USA), phone: 301-286-1023, fax: 301-286-4699, e-mail: hak.s.kim@nasa.gov 
Dakai Chen, NASA Goddard Space Flight Center (GSFC), Code 561.4, Greenbelt, MD 20771 (USA), phone: 301-286-8595,  
fax: 301-286-4699, e-mail: dakai.chen@nasa.gov 
Anthony M. Phan, MEI Technologies, Inc., c/o NASA Goddard Space Flight Center (GSFC), Code 561.4, Bldg. 22, Rm. 080,  
Greenbelt, MD 20771 (USA), phone: 301-286-1239, fax: 301-286-4699, e-mail: anthony.m.phan@nasa.gov 
Kenneth A. LaBel, NASA Goddard Space Flight Center (GSFC), Code 561.4, Greenbelt, MD 20771 (USA), phone: 301-286-9936,  
fax: 301-286-4699, e-mail: kenneth.a.label@nasa.gov 
 
 
 
 
 
 
Session Preference: Hardness Assurance 
Presentation Preference: Oral 
 
  
Megan C. Casey1, Robert A. Gigliuto2, Jean-Marie Lauenstein1, Edward P. Wilcox2, Hak Kim2, Dakai Chen1,  
Anthony M. Phan2, and Kenneth A. LaBel
1. NASA Goddard Space Flight Center (GSFC), Code 561.4, Greenbelt, MD 20771 USA 
1 
2. MEI Technologies, Inc., Seabrook, MD 20706 USA 
Destructive Single-Event Failures in Diodes
https://ntrs.nasa.gov/search.jsp?R=20130009065 2019-08-30T23:58:58+00:00Z
To be presented by Megan C. Casey at the Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Space 
Radiation Effects Conference (NSREC), July 8-12, 2013, San Francisco, California. 
 
 2 
Introduction 
In the 2012 Institute for Electrical and Electronics 
Engineers (IEEE) Nuclear and Space Radiation Effects 
Conference (NSREC) Radiation Effects Data Workshop 
(REDW) [1], O’Bryan, et al., highlighted destructive single-
event effects that were observed in DC-DC converters by two 
different manufacturers, International Rectifier (IR) [2] and 
Crane Aerospace [3].  In both cases, the failures were 
attributed to the shorting of the anode and the cathode of 
output diodes due to a heavy ion strike.  Additional testing 
was completed by looking at the M3G280515T, the flight 
version (as opposed to the M3G2804R513R5T, which is an 
Engineering Test Unit [ETU]) of the IR DC-DC converter [4]. 
Both IR parts are triple output DC-DC converters with 28 V 
inputs.  The flight version uses the same diodes as the ETU, 
but other components are replaced with radiation-hardened 
versions.  Similarly, these parts were also susceptible to 
destructive single-event effects.  The Crane DC-DC 
converters were the MTR28515, which is not a space-
qualified part, but does come with total ionizing dose data.  
Like the IR parts, it is also a triple output converter with a 28 
V input.  Figures 1a and 1b show images of the damage to the 
output diodes [1] in the IR engineering unit and the Crane 
flight part, respectively.  The failure in the IR part is along the 
guard ring, while the location of the failure in the diode used 
in the Crane converter is more centrally located. 
Hundreds, if not thousands, of diodes are routinely flown 
on spacecraft, and generally are not considered to be 
susceptible to single-event effects.  The implication of these 
diode failures could be catastrophic to scientific instruments, 
or even entire spacecraft, necessitating full understanding of 
the scope of the issue.  In this paper, the diodes internal to the DC/DC converters previously tested were 
independently irradiated in order to identify and understand the failure mechanism and then calculate failure rates 
to determine the severity of the potential impact to NASA missions. 
 
Test Facilities and Experimental Set-Up 
Parts Tested 
The diodes irradiated in this work are the ON Semiconductor MBR20200CT [5], which are a dual 200 V, 20 A 
Schottkey diodes.  This part was used on the outputs of both IR DC/DC converters.  A total of 45 MBR20200CT 
diodes were irradiated. 
The diode in the Crane converter is manufactured to the specifications of their own Source Control Drawing 
(SCD), but they are the equivalent to the Sensitron SD125SB45A [6].  These diodes are 45 V, 15 A Schottkey 
rectifiers.  These diodes are not only used in the MTR family of converters, but they are also used in the space-
qualified equivalents, the SMTR line.  25 diodes were available for testing, but ultimately, only 4 were irradiated. 
 
Test Facilities 
The Sensitron diodes were tested at Lawrence Berkeley National Laboratory’s (LBNL) 88” cyclotron using the 
10 MeV/amu beam cocktail.  The ON Semi diodes, however, were tested on multiple occasions at both LBNL and 
Texas A&M University’s (TAMU) Radiation Effects Facility at the Cyclotron Institute.  The ion beam cocktails 
used were the 10 MeV/amu tune at LBNL, and the 15 MeV/amu and 25 MeV/amu tunes at TAMU. 
 
 
 
 
(a) 
 
 
(b) 
 
Fig. 1.  The small dots are the locations where the 
metal melted due to the single-event in the (a) 
M3G2804R513R5TEM engineering model and in the 
(b) MTR28515 [1]. 
To be presented by Megan C. Casey at the Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Space 
Radiation Effects Conference (NSREC), July 8-12, 2013, San Francisco, California. 
 
 3 
Test Set-Up 
The experiments were conducted using the NASA GSFC high-
voltage power MOSFET motherboard, which is pictured in Figure 2 
with five of the MBR20200s mounted on daughter cards connected to 
the motherboard.  This board was designed to enable testing of 6 parts 
without having to enter the cave and manually move cables or parts.  
In order to test the diodes, no gate connection was made, and the 
cathode was connected to the source test points on the board.  
Likewise, the anode of the diodes was connected to the drain 
locations.  In the case of the MBR20200s, since they are dual diodes, 
the cathodes and anodes were simply shorted to each other.  
We used a Keithley 2410 SourceMeter for the anode and cathode 
voltages.  A Data Acquisition unit (DAQ), the Agilent 34907A, was 
used to switch between the six parts in the chamber at a given time.  
There was also a 1 GHz mixed-signal oscilloscope, a Tektronix 
MSO5104, to capture any transients or other waveforms that might be 
seen on the output.  A Keithley 2400 SourceMeter was also used to 
supply power to the relays on the motherboard.  We controlled all the 
equipment using a personal computer and two LabView programs, one to capture and save the waveforms from the 
oscilloscope and one to supply the appropriate voltage to the diodes and run the post-irradiation tests. 
 
Test Results 
ON Semiconductor MBR20200CT 
Previous work indicated that Schottky diode failures due to single-events [7] occur along the guard rings [8], 
which is where the MBR20200CT in the M3G2804R513R5TEM appear to fail as well.  In [8], Ralston-Good 
shows that a short is formed between the guard ring and the n+ substrate of Schottky diodes when an ionizing 
radiation pulse is simulated.  This short causes localized temperature rises from increased electric fields due to 
increased potential gradients over small areas.  This increase in temperature causes the carrier concentration to 
increase exponentially, leading to a mesoplasma [9, 10] at the guard ring.  A similar phenomenon could occur with 
the ion track from a heavy ion, shorting the guard ring and silicon substrate, leading to a mesoplasma at the guard 
ring. 
The ON Semi diodes were tested on four different occasions.  It was quickly determined that, independent of 
the IR DC-DC converters, the diodes are, in fact, susceptible to destructive SEEs.  EEE-INST-002 states that all 
diodes should be derated to 75% of rated voltage, so in theory, these diodes could be used up to a voltage of 150 V.  
Figure 3 shows the last reverse voltage value at which the 
diode was biased before it suffered a destructive failure.  The 
parts irradiated with 508 MeV V (here V is for Vanadium, 
rather than voltage) failed at voltages slightly greater than 
150 V.  The parts irradiated with 1032 MeV Kr, however, 
failed considerably below the 75% of rated voltage threshold.  
Fortunately, Kr is above the iron knee in the galactic cosmic 
ray linear energy transfer spectrum, so the abundance in space 
is lower, which will reduce the failure rate. 
Additionally, the last passing voltage appears to bottom 
out around Ag, as it has roughly the same last passing and 
failure voltages as Xe.  A similar phenomenon has been 
described by S. Liu, et al., in power MOSFETs [11].  The 
authors showed that a minimum field must be applied for 
power MOSFETs to be susceptible to single-event burnout.  
Ordinarily, the minimum drain voltage required for failure 
decreases with increasing atomic mass or increasing ion LET; 
however, when below the minimum field required for 
burnout, heavier ions no longer fail at a lower voltage than 
 
 
Fig. 3.  The last voltage at which an ON 
Semiconductor MBR20200CT diode was irradiated 
without destructive failure.  The error bars (many of 
which are smaller than the symbols) indicate the 
voltage at which the part did fail. 
 
 
Fig. 2.  High-voltage power MOSFET test 
board equipped with five MBR20200 
mounted on daughtercards. 
To be presented by Megan C. Casey at the Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Space 
Radiation Effects Conference (NSREC), July 8-12, 2013, San Francisco, California. 
 
 4 
their lighter counterparts.  Instead, the minimum failure drain 
voltage reaches an asymptote, and remains constant even 
when irradiated with heavier ions.  This appears to be 
occurring in the diodes as well. 
All data presented to this point have been at normal 
incidence.  Figure 4 shows the last passing reverse voltage as 
a function of effective LET.  The angles investigated with Ag 
were 10° and 30°, while with Xe, the parts were irradiated at 
angles of 10°, 30°, 45°, and 60°.  The 0° data in this figure are 
the Ag and Xe data included in Figure 3.  Surprisingly, the 
last passing voltage does not improve with angle as quickly as 
might be expected.  This is illustrated in Figure 5, where the 
last passing voltage is plotted as function of angle, rather than 
LET, for Ag and Xe.  The data up to and including the 45° 
points follow the cosine law, as expected; however, the 60° 
points make the trend much more linear in appearance.  This 
is likely due to the large charge collection volume inherent in 
diodes.  Unlike CMOS, where the collection volume is 
limited solely to the channel, the collection volume is really 
the entire silicon cathode.  As a result, the volume through 
which the ion track deposits charge does not decrease with the 
same severity at angle as it does through the small channels of 
MOSFETs. 
While it is difficult to accurately calculate destructive 
SEE cross-sections due to the delays associated with stopping 
the beam after the error has occurred, Figure 6 shows the 
failure cross-section as a function of Linear Energy Transfer 
(LET).  The data have a clear onset threshold; no failures 
were observed with 183 MeV O (LET = 2.19 MeV-cm2/mg), 
but they did occur at 195 V and 200 V with 216 MeV Ne 
(LET = 3.49 MeV-cm2
Using the data from the cross-section curve, failure rates 
can be calculated for the diode.  Table 1 shows the failures 
per device per day for a number of solar conditions in a near-
Earth interplanetary/geosynchronous orbit behind 100 mils 
(2.54 mm) of Al shielding. 
/mg).  The cross-section values 
associated with O are plotted as an upperbound by simply 
taking the inverse of the fluence at the last passing voltage, 
which was the rated voltage of the diode, 200 Vm because no 
failures were observed at this point. 
 
 
TABLE 1. 
Near-Earth interplanetary/geosynchronous failure rates for the 
MBR20200CT based on a variety of solar conditions. 
 
Errors/device-day 
Solar Min 1.66E-05 
Solar Max 4.36E-06 
Worst Week 9.26E-03 
Worst Day 4.64E-02 
Worst 5 Minutes 1.74E-01 
 
 
 
Fig. 4.  The symbols indicate the last voltage at which 
an ON Semiconductor MBR20200CT diode passed.  
This figure only includes data from ions taken at 
angle.  The 0° degree points are included as well and 
can also be found in Figure 3. 
 
 
Fig. 5.  Last passing reverse voltage as a function of 
angle for Ag and Xe irradiations of ON Semi 
MBR20200CT diodes.  The charge collection volume 
does not change drastically with angle, hence, the last 
passing voltage also does not change quickly. 
 
 
Fig. 6.  Failure cross-section as a function of LET for 
the MBR20200CT diode. 
To be presented by Megan C. Casey at the Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Space 
Radiation Effects Conference (NSREC), July 8-12, 2013, San Francisco, California. 
 
 5 
These values were calculated using CRÈME-MC with an onset LET of 3.49 MeV-cm2/mg and a saturated cross-
section of 10-5 cm-2
 
, based roughly on the average of the Xe cross-section values as found in Figure 4.  Based on the 
sheer number of diodes flying on a given spacecraft and the length of NASA missions, single-event-induced diode 
failures could become a serious issue. 
Sensitron SD125SB45A 
The Sensitron SD125SB45A 45 V Schottky diodes were irradiated with 1232 MeV Xe (LET = 58.8 MeV-
cm2/mg) at LBNL.  No diodes failed during these irradiations.  During the original MTR28515 experiments, the 
converters saw no destructive failures with TAMU’s 1934 MeV Xe, which has an LET of 51.5 MeV-cm2/mg after a 
30 mm air gap.  The failures only occurred in the converter when irradiated with 2714 MeV Ta (LET = 77.3 MeV-
cm2
 
/mg, also with a 30 mm air gap), indicating that either the minimum LET threshold was not met, or possibly 
that something other than an SEE failure was observed in the diode in the converter, latent ESD damage for 
instance.  Because the location of the failure, as indicated in Figure 1b, was not along the guard ring, like the 
MBR20200s, and the inability to destroy the diode independently, strengthens the argument that the failure in the 
MTR28515 may be due to something other than burnout in the diode.  Interestingly though, the diodes tested by 
Titus et al., in [8] were 150 V and 45 V Schottky rectifiers from IR, and like in this work, the 45 V diode did not 
fail under high dose rate conditions, but the parts with higher voltage ratings did. 
Conclusions 
In this summary, we have shown that diodes are susceptible to destructive single-event effects, and that these 
failures occur along the guard ring.  By determining the last passing voltages, a safe operating area can be derived.  
By derating off of those values, rather than by the rated voltage, like what is currently done with power MOSFETs, 
we can work to ensure the safety of future missions. 
However, there are still open questions about these failures.  Are they limited to a single manufacturer, a small 
number, or all of them?  Is there a threshold rated voltage that must be exceeded to see these failures?  With future 
work, we hope to answer these questions.  In the full paper, laser results will also be presented to verify that failures 
only occur along the guard ring. 
 
Acknowledgment 
The authors thank members of the Radiation Effects and Analysis Group (REAG) who contributed to the test 
results presented here Alyson D. Topper, Donald K. Hawkins, James D. Forney, and Stephen R. Cox.  Additionally, 
the authors would also like to acknowledge the personnel at LBNL and TAMU for their support during beam runs. 
 
References 
[1] O'Bryan, M.V.; LaBel, K.A.; Pellish, J.A.; Lauenstein, J.-M.; Dakai Chen; Marshall, C.J.; Casey, M.C.; Gigliuto, R.A.; Sanders, A.B.; Oldham, T.R.; 
Kim, H.S.; Phan, A.M.; Berg, M.D.; Marshall, P.W.; Ladbury, R.L.; Wilcox, E.P.; Boutte, A.J.; Musil, P.L.; Overend, G.A.; , "Compendium of Single 
Event Effects for Candidate Spacecraft Electronics for NASA," Radiation Effects Data Workshop (REDW), 2012 IEEE , vol., no., pp.1-9, 16-20 July 
2012. 
[2] International Rectifier M3G280515T Triple Output DC/DC Converter datasheet, available online: http://www.irf.com/product-
info/datasheets/hirel/m3gt.pdf 
[3] Crane Aerospace & Electronics Power Solutions MTR28515 Triple Output DC/DC Converter datasheet, available online: 
http://www.interpoint.com/product_documents/MTR_DC_DC_Converters.pdf 
[4] Observed Diode Failures in DC-DC Converters, available online:  
http://nepp.nasa.gov/workshops/etw2012/talks/Tuesday/T15_Gigliuto_Observed_Diode_Failures.pdf 
[5] MBR20200CT: 200 V, 20 A Schottky Rectifier, available online:  http://www.onsemi.com/PowerSolutions/product.do?id=MBR20200CT 
[6] Silicon Schottky Rectifier Die, available online:  http://www.sensitron.com/data_sheets/512.pdf 
[7] J.L. Titus, S. Skinner, G. Bloomfield, J. Ciezki, J.E. Smith, “ Dose-Rate Response of Reverse-Biased Power Schottky Diodes”, GOMAC Digest, Vol. 26, 
p. 411, 2001. 
[8] Ralston-Good, Jeremy.  “Analysis of Schottky Diode Failure Mechanisms During Exposure to Electron Beam Pulse Using TCAD Simulation,” MS thesis 
Vanderbilt University, Nashville, TN, 2002. 
[9] A. C. English, “Mesoplasmas and ‘Second Breakdown’ in Silicon Junctions,” Solid State Electonics, 6, pp. 511-521, 1963. 
[10] A. C. English, “Physical Investigation of the Mesoplasma in Silicon,” IEEE Trans. Electron Devices, ED-13, No 8/9, pp. 662-667, 1966. 
[11] Sandra Liu; Milt Boden; Huy Cao; Ed Sanchez; Jeffrey L. Titus; , "Evaluation of Worst-Case Test Conditions for SEE on Power DMOSFETs," 
Radiation Effects Data Workshop, 2006 IEEE , vol., no., pp.165-171, July 2006. 


Destructive Single-Event Failures in Diodes

Destructive Single-Event Failures in Diodes

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