Five-day-long ferroelectric memory effect in Pt∕(Bi,La)4Ti3O12∕HfO2∕Si structures

Abstract

In order to form metal–ferroelectric–semiconductor–insulator–semiconductor (MFIS) structures, hafnium oxide (HfO2) films were first deposited on Si(100) substrates at room temperature using an electron-beam evaporation method. Then, they were annealed in an O2 atmosphere at 800°C for 1min. No hysteretic characteristics were observed in the capacitance–voltage (C–V) measurement for the metal–insulator–semiconductor capacitors. On these films, lanthanum-substituted bismuth titanate [(Bi,La)4Ti3O12:BLT] films with 380nm in thickness were deposited by a sol–gel spin-coating method and annealed in an O2 atmosphere at 750°C for 30min. The MFIS sample showed the hysteretic C–V characteristics and the memory window width was about 0.9V for the voltage sweep of ±7V. Furthermore, the high and low capacitance values biased in the hysteresis loop were clearly distinguishable for over 5 days. The origin of the excellent data retention characteristics is discussed from a viewpoint of the transient current across the film.

Fabrication and properties of silicon-based (Bi,Sm)4Ti3O12 thin film

“…This is the desired mode for memory operation [16]. The memory windows of the loops are found to be around 2 and 4 V at the sweep amplitude of 3 and 5 V, respectively, which are much wider than that of (Bi,La) 4 Ti 3 O 12 /HfO 2 /n-Si (1 0 0) and (Bi,Sm) 4 Ti 3 O 12 /p-Si (1 0 0) [17,18]. The capacitance values are saturated to the maximum and minimum values in both the accumulation and the inversion regions, respectively.…”

Characterization of Au/Pb(Zr0.96Ti0.04)O3/Al2O3/Si antiferroelectric field-effect transistors for memory application

“…To enhance the memory retention, the high-k materials such as Al 2 O 3 [12], Si 3 N 4 [13], LaAlO 3 [14], HfO 2 [15][16][17], HfAlO [18,19], CeO 2 [20], MgO [21], Dy 2 O 3 [22], Y 2 O 3 [23,24], HfTaO [25], etc., have been used as a buffer layer between ferroelectric and semiconductor layers to reduce ionic interdiffusion and interfacial charge trapping. So far to now, the retention is not satisfied yet, since the memory window is maintained only for a few days, far shorter from the 10-year requirement.…”

Fabrication and characterization of Au/SBT/LZO/Si MFIS structure

“…Most insulators investigated as a buffer layer in an MFIS structure are high-k dielectric materials such as Ta 2 O 5 , ZrO 2 , HfO 2 , HfAlO x or Y 2 O 3 [5][6][7][8][9]. The LaZrO x (LZO) thin film has been recently reported to have a high dielectric constant of ≈20 and be chemically stable in contact with Si [10].…”