Study of the Effect of Metal/Semiconductor Interface Properties on a Resistance Switching Device
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0997-I07-06
Study of the Effect of Metal/Semiconductor Interface Properties on a Resistance Switching Device Manuel Villafuerte1,2, Silvia P. Heluani1, Gabriel Ju·rez1, David Comedi1,2, Gabriel Braunstein3, and Federico Golmar4 1 FÌsica, Lab. de FÌsica del SÛlido, Universidad Nacional de Tucum·n, Av. Independencia 1800, Tucum·n, 4000, Argentina 2 CONICET, Tucum·n, 4000, Argentina 3 Micron Technology, 9600 Godwin Drive, Manassas, VA, 20110 4 Lab. de AblaciÛn L·ser, Universidad de Buenos Aires, Buenos Aires, 1000, Argentina ABSTRACT N-doped ZnO thin films were deposited by pulsed laser deposition on SiO2/Si substrates. Xray diffraction analysis revealed that the films have the wurtzite structure and are highly oriented along the c-axis direction. Two Au and two Al electrical contacts were deposited by sputtering on the top surface of the samples, forming a symmetric two-terminal structure in each case. The current-voltage characteristics of the two-terminal structures, and the temperature dependence of the resistance switching effect, were studied in the 125-300 K temperature range. The results of these measurements are presented and discussed in terms of the different Schottky barrier heights, as well as in terms of interfacial defect-induced gap states. INTRODUCTION Memory switching and voltage controlled negative resistance phenomena have been investigated since the sixties on different materials such as amorphous semiconductors [1, 2, 3], ZnSe-Ge heteroestructures [4] and also reported for a variety of oxides such as Nb2O5 [5], Al2O3 [6], Ta2O5 [7], TiO2 [8] and NiO [9,10]. During year 2000, an effect known as Electric PulseInduced Resistance switching (EPIR) was reported in Pr0.7Ca0.3MnO3 thin films at room temperature [11]. In this effect, the magnitude of the electrical resistance between two electrodes changes after applying an electrical pulse, and this change is nonvolatile and reversible against the polarity change of the electric pulse. EPIR is distinguished from ìconventionalî resistance switching effect due to this polarity dependence feature [12]. Since the early researches various models have been proposed to describe the physical process involved in switching and memory in oxides. Mostly known are the formation of filaments exhibing ohmic conduction proposed by Dearnaley et al. [3] and, recently, a phenomenological model proposed by Rozemberg et al. that assumes the existence of three different domains between the electrodes, each one having different electrical propierties [13]. In the line of Dearnaley et al.ís work, Fors et al. [14] proposed that the switch is due to a shift in a valence state of a particular cation in the insulator producing a Mott metal ñinsulator transition. Despite the significant contributions of different models and experimental results reported, it is clear that the physical process involved, and the physical basis of many of the elements that appear in this subject (forming, domains, conductive paths, doping, hysteretic current voltage curves) are not well understood and l
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