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IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 41, NO. 10, OCTOBER 2013
Nanostructured Manganite Films as Protectors Against Fast Electromagnetic Pulses Nerija Žurauskien˙e, Member, IEEE, Saulius Baleviˇcius, Senior Member, IEEE, Laura Žurauskait˙e, Skirmantas Keršulis, Voitech Stankeviˇc, and Sonata Tolvaišien˙e Abstract— The effects of strong electric fields on the resistivity of thin nanostructured La-Ca(Sr)-Mn-O films, deposited on lucalox substrates by the metal–organic chemical vapor deposition technique, are investigated using electrical pulses with a pulselength of 5 ns and an amplitude of up to 500 V. The influence of the chemical composition of these films is analyzed to determine the optimal conditions for their use as protectors against fast electromagnetic pulses (EMPs) when operating at the temperature of liquid nitrogen as well as at room temperatures. It is shown that by changing the doping material (using Ca instead of Sr), it is possible to reduce the threshold voltage in these films and to obtain better limiting characteristics at lower amplitudes of such pulsed electric fields. Index Terms— Electroresistance, intentional electromagnetic interference (IEMI), manganites, protectors against electromagnetic pulses (EMPs), strong electric field effects, thin films.
I. I NTRODUCTION
R
ECENTLY interest in the development of new protective measures against the action of high-power electromagnetic pulses (EMPs) of various origins has increased [1]–[5]. The effects of space weather or other electromagnetic activity, such as those emanating from the detonation of high-altitude nuclear or nonnuclear weapons, all have a potential impact on electronic infrastructures. The increased demand of electronic systems to have higher density integrated circuits constructed in ever smaller dimensions increases their transient vulnerability. The induced effect resulting in an upset or damage in an electronic system is commonly referred to as intentional electromagnetic interference [6]. Considering the classification of intentional electromagnetic environment by frequency ranges, it should be noted, that the fast nuclear EMP component E1 [1], [7] as well as the ultrawideband EMP generated by highpower electromagnetic sources, which can range from simple homemade devices to advanced military systems [5], [8]–[10], all take place within several nanoseconds, subnanoseconds, and have high electric field strengths. Thus, they have sufficient power to disrupt or damage microelectronic systems,
Manuscript received November 30, 2012; revised April 25, 2013; accepted June 11, 2013. Date of publication June 28, 2013; date of current version October 7, 2013. Research conducted in the scope of the European Pulsed Power Laboratories known as the EPPL. This work was supported by the Research Council of Lithuania under Grant MIP-062/2012. N. Žurauskien˙e, S. Baleviˇcius, L. Žurauskait˙e, S. Keršulis, and V. Stankeviˇc are with Semiconductor Physics Institute, Center for Physical Sciences and Technology, Vilnius LT-01108, Lithuania (e-mail:
[email protected];
[email protected];
[email protected];
[email protected];
[email protected]). S. Tolvaišien˙e is with Vilnius Gediminas Technical University, Vilnius LT03227, Lithuania (e-mail:
[email protected]). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TPS.2013.2269480
computers, and other sensitive electronic devices. For this reason, the devices used to protect electronic systems against EMP need to have nanosecond turn-on times and to be able to dissipate large power throughout the entire pulse. In addition, these induced fault current signals are usually bipolar, thus symmetrical protectors are needed. Various attempts are made to develop the protection devices able to withstand the action of such high-power EMPs [4], [5] and still be able to operate at the speeds needed. Switches based on gas discharge plasma limiters, varistors, surge arresters, and other protectors are too slow due to their large intrinsic capacitance, thus limiting their response times to microseconds [11], [12]. It is demonstrated that thin polycrystalline manganite films connected in parallel to a transmission line can be used as protectors against fast EMP [5], [13], [14]. The operation of such protectors is based on their nonlinear current–voltage (I–V ) characteristic, which is due to the so-called electroresistance effect [15] present in these films. It is shown that while La0.67 Ca0.33 MnO3 (La-Ca-Mn-O) films grown by the pulsed laser deposition (PLD) technique have good limiting characteristics, their high maximum resistivity (∼30 Ωcm) [13] makes it difficult to fabricate protectors in small sizes (
