Ferroelectricity in yttrium-doped hafnium oxide

Abstract

Structural incommensurate modulation rule in hexagonal Ba(Ti1-xMx)O3-δ (M = Mn, Fe) multiferroics AIP Advances 2, 042129 (2012) Water assisted gate induced temporal surface charge distribution probed by electrostatic force microscopy J. Appl. Phys. 112, 084329 (2012) Influence of target composition and deposition temperature on the domain structure of BiFeO3 thin films AIP Advances 2, 042104 (2012) Nanodomain structures formation during polarization reversal in uniform electric field in strontium barium niobate single crystals J. Appl. Phys. 112, 064117 (2012) The effect of the top electrode interface on the hysteretic behavior of epitaxial ferroelectric Pb(Zr,Ti)O3 thin films with bottom SrRuO3 electrode J. Appl. Phys. 112, 064116 (2012) Additional information on J. Appl. Phys. Structural and electrical evidence for a ferroelectric phase in yttrium doped hafnium oxide thin films is presented. A doping series ranging from 2.3 to 12.3 mol% YO 1.5 in HfO 2 was deposited by a thermal atomic layer deposition process. Grazing incidence X-ray diffraction of the 10 nm thick films revealed an orthorhombic phase close to the stability region of the cubic phase. The potential ferroelectricity of this orthorhombic phase was confirmed by polarization hysteresis measurements on titanium nitride based metal-insulator-metal capacitors. For 5.2 mol% YO 1.5 admixture the remanent polarization peaked at 24 lC=cm 2 with a coercive field of about 1.2 MV=cm. Considering the availability of conformal deposition processes and CMOS-compatibility, ferroelectric Y:HfO 2 implies high scaling potential for future, ferroelectric memories.

The origin of ferroelectricity in Hf1−xZrxO2: A computational investigation and a surface energy model

“…Furthermore, ferroelectricity was found in the 9 nm mixed oxide thin film Hf0.5Zr0.5O2 (HZO) 2 deposited on TiN electrodes, although neither the pure HfO2 nor the pure ZrO2 film exhibit ferroelectricity. The existence of a true ferroelectric effect has been confirmed by various experiments such as P-V and C-V measurements 8 as well as retention extrapolated up to 10 years 12 and the occurrence of orthorhombic peaks in XRD measurements 13 . ZrO2 was also studied extensively in the context of functional thin films since its tetragonally stabilized form has a high dielectric constant.…”

Polarization switching behavior of Hf–Zr–O ferroelectric ultrathin films studied through coercive field characteristics

“…This is consistent with previous results. 1, 8,10,11,15) First, the emergence of the ferroelectric phase in HfO 2 films was discussed on the basis of mechanical stress through the TiN electrodes at the bottom and top of HfO 2 films. 3) Later, it was demonstrated that the top TiN capping layer is not necessary, although it affects the volume fraction of the ferroelectric phase in the film.…”

“…1,4,5) The ferroelectricity of HfO 2 films is maximized in ultrathin films of around 10 nm thickness. Crystallization of HfO 2 films begins at low annealing temperatures of around 400°C, 11) and the ferroelectric property is stable after annealing at 1000°C. 2,3) Currently, ultrathin HfO 2 films are attainable by atomic layer deposition (ALD) and are already utilized as the major gate stack material for advanced metal-oxide-semiconductor field-effect transistors (MOSFETs) in largely integrated circuits (LSIs).…”

“…Since the first report of ferroelectricity in Si-doped HfO 2 crystalline films, ferroelectric HfO 2 films have been reported using many types of dopants, such as Si, 1-6) Zr, [6][7][8][9][10] Y, [4][5][6][11][12][13] Al, [4][5][6]14) Gd, 4,15,16) Sr, 5,17) La, 18,19) Sc, 6) Ge, 6) and N. 6,20) Nondoped HfO 2 films also show ferroelectricity when an appropriate amount of oxygen deficiency is introduced. 12,[21][22][23] It is widely recognized that the ferroelectricity in HfO 2 is attainable in a particular range of dopant concentrations, and its spontaneous polarization is induced by the displacement of oxygen ions in the noncenter symmetric orthorhombic phase crystal.…”

Upconversion luminescence, ferroelectrics and piezoelectrics of Er Doped SrBi4Ti4O15

“…It believes that the strategy reported here could be extended to a variety of BLSFs oxides for the design of new ferroelectric materials with optical and electric multifunction and this strategy could be applied to the newly discovered promising ferroelectric materials such as hafnium oxide which ferroelectric properties can be controlled by doping rare earth elements. 73 …”