Effects of electron radiation on commercial power MOSFET with buck converter application

Effects of electron radiation on commercial power MOSFET with buck converter application 1 corresp first-author Corresponding author, Sheik Fareed Ookar Abubakkar. E-mail address: fareedcahcet12@gmail.com Corresponding author, Sheik Fareed Ookar Abubakkar. E-mail address: fareedcahcet12@gmail.com fareedcahcet12@gmail.com 1 2 1 1 1 Department of Electrical and Computer Engineering, International Islamic University, Kuala Lumpur, 53100, Malaysia. Department of Electrical and Computer Engineering, International Islamic University, Kuala Lumpur, 53100, Malaysia. Industrial Technology Division, Agency Nuclear Malaysia, Kuala Lumpur,43000, Malaysia Industrial Technology Division, Agency Nuclear Malaysia, Kuala Lumpur,43000, Malaysia Microelectronic power converters such as buck and boost converter are required to be tolerant to radiations including electron radiation. This paper examines electron radiation effects on the I-V characteristics of VDMOSFET and its corresponding effects in buck converter. Analysis of the electrical characteristics shows that after irradiation the threshold voltage and drain current for all VDMOSFETs degraded more than 2 orders of magnitude. The impact of this electrical degradation has been investigated in an application of typical buck converter circuit. The buck converter with n-channel switching transistor shows that after irradiation its output voltage increased with the drain current in the n-channel ZVN4424A VDMOSFET, while the buck converter with p-channel switching transistor shows its output voltage decreased with the drain current in the p-channel ZVP4424A VDMOSFET after irradiation. VDMOSFET I-V characteristics Drain current Buck converter Electron radiation. 1 Introduction 1 The commercial diodes and transistors such as BJT(bipolar junction transistor) and VDMOSFET(vertical double diffused power MOSFET) have attracted considerable interest in the satellite and power converter applications due to its low drive requirement, low ‘on’ resistance and high frequency of operations [ 1 1 , 2 2 , 3 3 ] . Most of the recent works in these field focus on the study of radiation-induced single-event response, single event burn-out and single event gate rupture as to provide a better understanding on the device radiation resistance with respect to the single-ion striking at a sensitive nodes [ 4 4 ] . Although significant improvements have been observed in the performance of the VDMOSFET in recent years, some other factors such as switching speed of the VDMOSFET has not been widely reported. Previously, there were several works associated with the investigation of total ionizing dose effects on the VDMOSFET [ 5 5 ] utilized as the switching transistor in the microelectronics power converters. In this paper we present the electrical performance degradation of the individual VDMOSFET components that are used in power converter circuit. For n-channel VDMOSFET, the induced damage can be manifested as positive charges trapped in the oxide layer, while in the p-channel, the defects can be either in the physical damaged region or scattering centers [ 6 6 , 7 7 ] . As a result of these defects, the switching performance of the VDMOSFET changes with the amount of charges inside the non-isolated gate oxide layer [ 8 8 , 9 9 ] . To study the impact of electrical characteristics degradation, the VDMOSFET performance is assessed by utilizing it in a buck converter circuit at different switching frequencies [ 10 10 ] . The I - V characteristics of the VDMOSFET before and after radiation, and the buck converter response after the VDMOSFET being irradiated, are discussed in details. 2 Experimental details 1 Commercial VDMOSFET from Diode Inc consisting of n-channel (ZVN4424A) and p-channel (ZVP4424A), with voltage rating of 20–200 V, were chosen for investigation. Electrical characterization of all devices before and after irradiation were carried out using Keithley measurement system 4200 in the Electronics Laboratory at International Islamic University Malaysia. The electrical characteristics of the n-channel ZVN4424A and p-channel ZVP4424A were done on three devices to check for repeatability. The selected VDMOSFETs were irradiated to 50, 100 and 200 kGy with 3 MeV electron beams from the Alutron accelerator at Agency Nuclear Malaysia. In the irradiation, all the test components were placed in a metallic tray for proper exposure, and all devices were made electrically floating. For each n-type and p-type VDMOSFET, eight devices from the same model were measured for each dose. All the irradiated devices were then used as switching transistors in the 10 V input and 5.5 V output voltage DC/DC buck converter. 3 Results and Discussion 1 3.1. I - V characteristics 2 Room temperature sub threshold I - V characteristics of the n-channel ZVN4424A and the p-channel ZVP4424A irradiated to 0, 50, 100 and 200 kGy are shown in Fig. 1 Fig. 1 . It is observed that the threshold voltage of the devices, V th , shifted as a function of radiation dose for all devices. Before irradiation, the threshold voltage was V th = −1.5 V for the p-channel ZVP4424A and V th = 1.7 V for the n-channel ZVN4424A; while after 50, 100 and 200 kGy irradiation, the threshold voltages decreased by 8±3V, 10±5V, 13±6V in ZVP4424A and by 2±1V, 4±1V, 7±1V in ZVN4424A,respectively. The threshold voltage shifts in the p-channel is due to radiation induce positive charges in the interface traps [ 8 8 ] . As more negative voltage is applied to the gate of a pmos device, the interface traps moves below the Fermi level and act as donors [ 11 11 ] . When this negative gate-source voltage increases, the donor interface traps contribute more positive charges for channel conduction. Therefore the threshold voltage becomes more negative in the p-channel VDMOSFET. As for the n-channel VDMOSFETs, the threshold voltage becomes negative as a result of radiation-induced positive charges dominated in the oxide traps [ 12 12 ] . Charges in the traps forced the device to turn-on at negative bias when the electric field direction change from the silicon substrate to the insulator. Figure 2 Figure 2 shows the threshold voltage shift (∆ V th ) for the n-channel and p-channel devices irradiated to 50, 100 and 200 kGy. The square and circular bars indicate the n-channel and p-channel VDMOSFET threshold voltage shifts, respectively. Each data point represents the average ∆ V th while the error bars indicate the standard deviations. It can be seen that the threshold voltage shifts in the p-channel VDMOSFET is larger than that of the n-channel VDMOSFET [ 13 13 ] . As Ristic et al . discussed in Ref. [ 14 14 ], this is due to the hot-carrier injection by negative electric field in the p-channel VDMOSFET. The hot-carrier injection affects the threshold voltage through the tunneling process of hot electrons from the gate/substrate into the oxide. Hot electrons accelerate by the negative electric field and produce more electron-hole pairs in the oxide. These cause a large decrease in threshold voltage of pMOS devices. Another important factor is the drain current degradation, as this affects the switching characteristics [ 15 15 ] . Fig. 3 Fig. 3 shows the drain current characteristics of p-channel and n-channel VDMOSFET before and after EB irradiation. At drain-source voltage of −3V, the drain current decreased by 0.047, 0.048 and 0.050 µA for 50,100 and 200 kGy irradiations, respectively. The 0.050 µA decrease at 200 kGy corresponds to 2 orders of magnitude decrease in the drain leakage current. This decrease is likely due to radiation-induced oxide damage [ 16 16 ] also known as the formation of physically damaged region (PDR). When these defects localized in the interface of the p-channel VDMOSFET, it decreases the drain leakage current by formation of scattering centers that reduces the carrier mobility [ 6 6 ] . Unlike the p-channel VDMOSFET, the drain leakage current of the n-channel is found to increase by 5 orders of magnitude for all dose levels. As Cester et al . pointed out, [ 17 17 , 18 18 ] this may be due to accumulation of positive charges in the oxide layer of the n-channel VDMOSFET. The positive charges induce current through recombination process. The drain current degradation in the n-channel and p-channel VDMOSFET is a consequence of negative threshold voltage shifts which forces the device to turn on earlier in the n-channel and delay the turn on in the p-channel VDMOSFET. The next part illustrates these effects of degradation in the buck converter. 3.2. Irradiated VDMOSFETs impact on buck converter 2 The degradation of threshold voltage affects the I - V characteristics and hence the switching behaviors of the VDMOSFET in power converter applications [ 15 15 , 19 19 ]. A buck converter circuit with 10V DC input and 5.5V output shows degradation in its switching characteristics through radiation-induced threshold voltage shifts in VDMOSFET. The circuit of the buck converter is shown in Fig. 4 Fig. 4 . The switching speed is increased by varying signal generator output frequencies from 1 kHz to 100 kHz while a clamped inductive load is connected at the VDMOSFET drain to reduce power dissipation [ 20 20 ] . A buck converter circuit shown in Fig. 4 Fig. 4 was simulated in pspice for the n-channel and p-channel switching transistors. The output voltage of the circuit was investigated for each model of the VDMOSFET before and after irradiation. The simulated of the resistors, capacitors and inductors were chosen to be implemented in the experimental setup. In the experimental analysis, the amount of output voltage degradation was measured by calculating the ratio of the output voltage. Fig. 5(a) Fig. 5(a) shows a plot of the experimental output voltage ratio of buck converter consisting of p-channel ZVP4424A before and after being irradiated to 50, 100 and 200 kGy. One sees that the ratio of output voltages decreases with increasing doses. This is due to the consequence of the drain current decrease of the VDMOSFET after irradiation as shown in Fig. 3(a) Fig. 3(a) . The output voltage of the p-channel buck converter decreases with the drain leakage current of the VDMOSFET. This implies that there is degradation of the power conversion in the buck converter. In addition to this, the output voltage ratio V out_after / V out_before was investigated at frequencies of 1, 10 and 100 kHz, which were chosen based on its application in radiation harsh environments as shown in previous work [ 21 21 ] . The V out_after / V out_before ratio decreased with the initial output voltage before irradiation. Table 1 Table 1 summarizes the p-channel buck converter output voltage at 50, 100 and 200 kGy with respect to switching frequencies.. 1 1 Doses(kGy) 1 1 Frequency (kHz) 2 1 Output voltage (V) 2 1 V out_after / V out_before 1 1   1 1   1 1 ZVP 1 1 ZVN 1 1 ZVP 1 1 ZVN 1 1 50 1 1 1 1 1 1.3 1 1 6.3 1 1 0.26 1 1 1.26 1 1   1 1 10 1 1 1.4 1 1 6.3 1 1 0.28 1 1 1.26 1 1   1 1 100 1 1 1.7 1 1 6.4 1 1 0.34 1 1 1.28 1 1 100 1 1 1 1 1 1.2 1 1 6.9 1 1 0.24 1 1 1.38 1 1   1 1 1 1 1 1.4 1 1 6.9 1 1 0.28 1 1 1.38 1 1   1 1 100 1 1 1.6 1 1 6.6 1 1 0.32 1 1 1.32 1 1 200 1 1 1 1 1 1.2 1 1 7.1 1 1 0.24 1 1 1.42 1 1   1 1 10 1 1 1.2 1 1 7.0 1 1 0.24 1 1 1.40 1 1   1 1 100 1 1 1.5 1 1 6.8 1 1 0.30 1 1 1.36 From Table 1 Table 1 , the V out_after / V out_before ratio increases with the frequency for all dose levels. The output voltage ratio calculation shows that when the frequencies increases the output voltage comes closer to the desired value. It is believed that this is due to the increase in drain current through charge pumping for larger frequencies [ 22 22 ] . When the current passes the inductive circuit, the output voltage increases by mutual inductance. Figure 5(b) Figure 5(b) shows the V out_after / V out_before ratio of buck converter consisting of ZVN4424A n-channel before and after being irradiated to 50, 100 and 200 kGy. Unlike the results of the p-channel circuit, the V out_after / V out_before ratio of the n-channel irradiated buck converters increase with the irradiation dose. This is due to the VDMOSFET drain current increase after irradiation as shown in Fig. 3(b) Fig. 3(b) . The buck converter output voltage increases with the drain leakage current which reduces the efficiency of the buck converter applications. Also, the output voltage and V out_after / V out_before of the n-channel VDMOSFET buck converter circuit was investigated at 1, 10 and 100 kHz. Table 1 Table 1 also shows the summary of the n-channel buck converter output voltage response at 50,100 and 200 kGy with respect to the switching frequencies. The output V out_after / V out_before ratio increases with the frequency for all dose levels. It is found that when the frequency increases the output voltage are closer to the desired value. The power loss of the buck converter is calculated using the equation below: P loss = I 2 out RDs (on) V out / V in As shown in Table 2 Table 2 , the power loss increases for the irradiated n-channel VDMOSFET, but reduces for the irradiated p-channel VDMOSFET. After weighing all the results it is clear that the degradation of the output voltage in p-channel is worse than the magnitude of the power loss than the n-channel. However for critical applications where power losses are important perhaps p-channel based buck converter circuit may be preferred. 1 1 Doses (kGy) 1 1 ZVN4424A 1 1 ZVP4424A 1 1 0 1 1 3.2 1 1 4.5 1 1 50 1 1 3.9 1 1 1.5 1 1 100 1 1 4.2 1 1 1.9 1 1 200 1 1 4.4 1 1 2.4 4 Conclusion 1 The radiation response of the VDMOSFET and its corresponding effects on the buck converter output voltage were investigated with electron radiation dose level of 50, 100 and 200 kGy. The results shows that both the p-channel ZVP4424A and the n-channel ZVN4424A VDMOSFET’s threshold voltage shifts to negative with increasing dose level. The buck converter consisting of ZVP4424A p-channel shows a decrease in the output voltage with increasing radiation dose. Consequently, the output voltage increased with increasing frequencies in the p-channel buck converter. This is believed to be due to the decreased of drain current leakage of the ZVP4424A. On the other hand buck converter consisting of ZVN4424A n-channel shows an increase in the output voltage with increasing radiation dose. Thus, the output voltage decreased with increasing frequencies in the n-channel buck converter. This is believed to be due to the increase of drain current leakage of the ZVN4424A. These results conclude that the n-channel buck converter circuit shows less degradation in the output voltage ratio compared to the n-channel buck converter. Increase in frequency improves the output voltage ratio of both the n-channel and the p-channel buck converter. References B. J. Baliga . Modern Power Devices . New Jersy (USA) : Wiley-Interscience Publication , 1987 , 404 - 452 Modern Power Devices M.M. OO , N. K. B. A. M. Rashid , J.B.A. Karim , et al . Electrical characterization of commercial NPN bipolar junction transistors under neutron and gamma irradiation , Nucl Technol Radiat 2014 , 29 , 46 - 52 . DOI: 10.2298/NTRP1401046O http://doi.org/10.2298/NTRP1401046O Electrical characterization of commercial NPN bipolar junction transistors under neutron and gamma irradiation D.A Fauzi , N. K. A. Md Rashid , M. R. Mohamed Zin , et al . Neutron radiation effects on the electrical characteristics of InAs/GaAs quantum dot-in-a- well structures . IEEE Transactions on Nuclear Science , 2015 , 62 , 3324 - 3329 . DOI: 10.1109/TNS.2015.2478450 http://doi.org/10.1109/TNS.2015.2478450 Neutron radiation effects on the electrical characteristics of InAs/GaAs quantum dot-in-a- well structures J.L. Titus , C.F. Wheatley , M. Allenspach , et al . Influence of ion beam energy on SEGR failure thresholds of vertical power MOSFETs . Nuclear Science, IEEE Transactions on , 1996 , 43 , 2938 - 2943 , DOI: 10.1109/23.556889 http://doi.org/10.1109/23.556889 Influence of ion beam energy on SEGR failure thresholds of vertical power MOSFETs S.G. Cappello , C. Parlato , A. Rizzo , et al . Gamma-ray irradiation tests of CMOS sensors used in imaging techniques . Nuclear Technology & Radiation Protection , 2014 , 29 , S14 - S19 , DOI: 10.2298/NTRP140SS14C http://doi.org/10.2298/NTRP140SS14C Gamma-ray irradiation tests of CMOS sensors used in imaging techniques A. Cester , S. Gerardin , A. Paccagnella , et al . Drain current decrease in MOSFETs after heavy ion irradiation . IEEE Transactions on Nuclear Science , 2004 , 51 , 3150 - 3157 DOI: 10.1109/TNS.2004.839203 http://doi.org/10.1109/TNS.2004.839203 Drain current decrease in MOSFETs after heavy ion irradiation M.M. Pejović , S.M. Pejović , D. Stojanov , et al ., Sensitivity of RADFET for gamma and X-ray doses used in medicine . Nucl Technol Radiat , 2014 , 29 , 179 - 185 , DOI: 10.2298/NTRP1403179P http://doi.org/10.2298/NTRP1403179P Sensitivity of RADFET for gamma and X-ray doses used in medicine J.A. Felix , M.R. Shaneyfelt , P. E. Dodd , et al . Radiation-induced off-state leakage current in commercial power MOSFETs . Nuclear Science, IEEE Transactions on , 2005 , 52 , 2378 - 2386 , DOI: 10.1109/TNS.2005.860724 http://doi.org/10.1109/TNS.2005.860724 Radiation-induced off-state leakage current in commercial power MOSFETs T. S. Kevkić , M.T. Odalović , D.M. Petković , A Stochstic model of gamma-ray induced oxide charge distribution and threshold voltage shift of MOS transistors , Nucl Technol Radiat , 2012 , 27 , 33 - 39 , DOI: 10.2298/NTRP1201033K http://doi.org/10.2298/NTRP1201033K A Stochstic model of gamma-ray induced oxide charge distribution and threshold voltage shift of MOS transistors D. V. Boychenko , L. N. Kessarinkiy , A. Y. Nikiforov . Investigation of low dose rate effects in DC/DC converters . 14th European Conference on Radiation and Its Effects on Components and System (RADECS) , 2013 , 1 - 3 . DOI: 10.1109/RADECS.2013.6937395 http://doi.org/10.1109/RADECS.2013.6937395 Investigation of low dose rate effects in DC/DC converters P.J. McWhorter , P.S. Winokur , R.A. Pastorek . Donor/acceptor nature of radiation-induced interface traps , Nuclear Science, IEEE Transactions on , 1998 , 35 , 1154 - 1159 , DOI: 10.1109/23.25433 http://doi.org/10.1109/23.25433 Donor/acceptor nature of radiation-induced interface traps G. Prakash , P. Ganesh , Y.N. Nagesha , et al , Effect of 30 Mev Li 3+ ion and 8 MeV electron irradiation on n-channel MOSFETs . Radiation Effects and Defects in Solids , 2002 , 157 , 323 - 331 , DOI: 10.1080/10420150213002 http://doi.org/10.1080/10420150213002 Effect of 30 Mev Li 3+ ion and 8 MeV electron irradiation on n-channel MOSFETs M.M. Pejovic , M.M. Pejović , A.B. Jakšić , et al . Successive gamma-ray irradiation and corresponding post-irradiation annealing of PMOS dosimeters . Nucl Technol Radiat , 2012 , 27 , 341 - 345 , DOI: 10.2298/NTRP1204341P http://doi.org/10.2298/NTRP1204341P Successive gamma-ray irradiation and corresponding post-irradiation annealing of PMOS dosimeters G.S. Ristic . Defect behaviors during high electric field stress of p-channel power MOSFETs . Device and Materials Reliability, IEEE Transactions on , 2012 , 12 , 94 - 100 , DOI: 10.1109/TDMR.2011.2168399 http://doi.org/10.1109/TDMR.2011.2168399 Defect behaviors during high electric field stress of p-channel power MOSFETs Y. He , Y. En , H. Luo , et al ., The irradiation effect and failure analysis of DC-DC power converter , 16th IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits , Suzhou, Jiangsu 2009 . 385 - 387 , DOI: 10.1109/IPFA.2009.5232625 http://doi.org/10.1109/IPFA.2009.5232625 The irradiation effect and failure analysis of DC-DC power converter A. Cester , S. Gerardin , A. Paccagnella , et al . Drain current decrease in MOSFETs after heavy ion irradiation . Nuclear Science IEEE Transaction on , 2004 , 51 , 3150 - 3157 , DOI: 10.1109/TNS.2004.839203 http://doi.org/10.1109/TNS.2004.839203 Drain current decrease in MOSFETs after heavy ion irradiation A.H Johnston and T.F. Miyahira . Radiation damage in power MOSFET optocouplers . Nuclear Science, IEEE Transactions on , 2007 , 54 , 1104 - 1109 , DOI: 10.1109/TNS.2007.903172 http://doi.org/10.1109/TNS.2007.903172 Radiation damage in power MOSFET optocouplers J.P Colinge , V.S. Lysenko , A. Nazarov . Physical and Technical Problems of SOI Structures and Devices , Netherlands : Springer , 1995 , 133 - 180 . Physical and Technical Problems of SOI Structures and Devices P.C. Adell , R.D. Schrimpf , B.K. Choi , et al . Total-dose and single-event effects in switching DC/DC power converters . Nuclear Science, IEEE Transactions on , 2002 , 49 , 3217 - 3221 , DOI: 10.1109/TNS.2002.805425 http://doi.org/10.1109/TNS.2002.805425 Total-dose and single-event effects in switching DC/DC power converters D. France , G. Charitat , P. Dupuy , et al . Clamped inductive switching of LDMOST for smart power IC's, Proceedings of the 10th International Symposium , in Power Semiconductor Devices and ICs , Kyoto , 1998 , 359 - 362 , DOI: 10.1109/ISPSD.1998.702715 http://doi.org/10.1109/ISPSD.1998.702715 Clamped inductive switching of LDMOST for smart power IC's, Proceedings of the 10th International Symposium V.L. Paul , M. Jules . High performance Ka-band frequency down converter for deep space application . European Space Agency’s Operation Center High performance Ka-band frequency down converter for deep space application P. Habas , Z. Prijic , D Pantic , et al ., Charge-pumping characterization of SiO2/Si interface in virgin and irradiated power VDMOSFETs , Electron Devices, IEEE Transactions on , 1996 , 43 , 2197 - 2209 , DOI: 10.1109/16.544392 http://doi.org/10.1109/16.544392 Charge-pumping characterization of SiO2/Si interface in virgin and irradiated power VDMOSFETs 10.1007/s41365-017-0189-8 The work is funded by Internationl Islamic University Malaysia (No. EDW B14-159-1044). 2016-02-18 2016-07-30 2016-08-12 2017-01-31 2017-03-01 2021-04-11 © China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, ChineseNuclear Society and Springer Nature Singapore Pte Ltd. 2017 This is a post-peer-review, pre-copyedit version of an article published in Nuclear Science and Techniques. The final authenticated version is available online at: http://dx.doi.org/10.1007/s41365-017-0189-8 http://dx.doi.org/10.1007/s41365-017-0189-8 . 2017 Nuclear Science and Techniques 03 28