Photosensitive metal-insulator-metal like capacitor on silicon with SrFeO-F nano particles embedded in the insulator stack

2^nd International Conference and Exhibition on Materials Science and Chemistry

July 13-14, 2017 Berlin, Germany

V Mikhelashvili, R Padmanabhan, G Ankonina, Y Kauffmann, G Atiya and G Eisenstein

Technion � Israel Institute of Technology, Israel

Posters & Accepted Abstracts: J Material Sci Eng

Abstract :

We have demonstrated a new type of varactor comprising a metal-insulator-semiconductor (MIS) structure, which incorporates Fe mixed with SrF2 nanoparticles (NPs) like SrFeO-F, embedded in an insulator stack, between thermal SiO2 and atomic layer deposited (ALD) HfO2 sub-layers. This is the consequence of the ALD and rapid thermal annealing processes, which initiate the fluoridation-oxidation and crystallization of the electron-beam gun deposited SrF2-Fe-SrF2 sub-layers, which was seen in electron energy loss and energy dispersive X-ray spectroscopy measurements, resulting in the formation of high-density positive charge sites of the oxygen reduced Fe ions, which, in turn, induce dipole-type traps with electronic polarization. Measured capacitance is biasindependent, which resembles the behavior of a metal-insulator-metal (MIM) diode; except that, here, the capacitance depends on illumination and exhibits a strong frequency dispersion. Due to large density of traps at the interface, there is significant band-bending at Si-interface irrespective of the applied voltage (due to pinning of the Fermi level), causing the formation of interfacial inversion layer, playing role of the second electrode. The capacitance is enhanced in the presence of illumination, while capacitance dispersion is rather conventional, reducing with increased frequency. The varactor exhibits extremely low quadratic voltage coefficient. The obtained characteristics are compared with two other MIS structures, one containing Fe but no SrF2 sub-layers, which behave as nonvolatile memory system with large hysteresis of 7 V; and another that contains only the SiO2 and HfO2 stack, which has conventional MIS capacitance-voltage characteristics with extremely low hysteresis of 0.3 V. The proposed MIM like capacitor is compatible with standard CMOS technology and can be prepared at relatively low temperatures. Additionally, it can be integrated within different optoelectronic circuits operating at moderate frequencies.

Biography :

Email: beso@ee.technion.ac.il