This chapter discusses in detail a RS HfO2-based memory cell with a metal-insulator-metal (MIM) vertical structure in which the HfO2 was deposited by Atomic Layer Deposition (ALD). The author carries out a statistic study on the effect of the HfO2 deposition process conditions on the resistive switching behavior. The chapter investigates the transient currents during 5-ns resistive switching operations. It proposes a short voltage pulse induced electroforming. The chapter models the current transport in metal-oxide-metal structures to gain an in-depth insight into the electroforming process. It reports the fabrication and electrical characterization of two-terminal multistate memory devices based on VO2/TiO2 thin film microcantilevers. The chapter reports on the feasibility of the Ge2Sb1Te4, Ge3Sb4Te8 and Ge2Sb2Te4 alloys and the effect of vacancies on their physical properties. It aims to determine. atomic layer deposition; cantilevers; MIM structures