Electrophysical characteristics of germanium MIS structures with rare-earth element fluorides

Abstract

The electrical properties of MIS structures with rare-earth element fluorides on germanium substrates were studied to analyze the possibility of using these materials as gate dielectrics of devices. The structures are also studied from the point of view of assessing the degradation of their electrophysical properties under the action of electric fields of ~108 V/m, which act on the dielectric during electroforming, since the MIS structures with rare-earth element fluorides have the property of bistable switching. Studies of the I-V and C-V characteristics show that all structures have approximately the same value of the density of surface states at the rare-earth element / Ge fluoride interface. The leakage currents in the MIS structures with TmF3 and SmF3 film are less than in the MIS structures with NdF3 film of greater thickness. There is also no effect of reducing the current density when using the double film structure CeF3/DyF3. The most promising material with a low leakage current at a fairly high value of the dielectric constant in germanium MIS structures is thin-film samarium fluoride.