To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The growth of HfO2 thin films on a HF-dipped p-Si(100) substrate at 200 °C by atomic-layer deposition (ALD) using Hf[N(C2H5)(CH3)]4 and H2O vapor as precursors is demonstrated. Uniform HfO2 thin films are obtained on a 4-in. silicon wafer, and the energy-band gap and band offset are determined by x-ray photoelectron spectroscopy analysis. The as-deposited HfO2 thin film is amorphous and able to crystallize at 500 ∼ 600 °C with only the monoclinic phase. As for the electrical performance of Au–Ti–HfO2–Si metal oxide semiconductor capacitors, a dielectric constant of ∼17.8 and an equivalent oxide thickness value of ∼1.39 nm are obtained from the 40-cycle ALD film after annealing at 500 °C. In addition, the breakdown field is in the range of 5 ∼ 5.5 MV/cm, and the fixed charge density is on the order of 1012 cm−2, depending on the annealing temperatures. The interface quality of HfO2 thin films on silicon is satisfactory with an interface-trap charge density of ∼3.7 × 1011 cm−2 eV−1.
The effect of nanoscale Pt particles embedded in ferroelectric matrix on the polarization switching characteristics of Pb(Zr0.5Ti0.5)O3 (PZT) thin films of low thickness was investigated. Two different nanocomposite structures of PZT-Pt thin films were fabricated for the study. The first one incorporated a single layer of Pt nano-particles embedded in the PZT film, which was formed by annealing an ultrathin Pt layer that had been inserted into the middle of the deposited PZT. The other one had Pt nano-particles embedded uniformly and coherently in the lattice of the PZT matrix, which was generated by annealing the cosputtered films of PZT and Pt. The electric field applied on the films can be locally intensified near the embedded Pt particles, which markedly enhances the polarization switching characteristic of the above PZT-Pt nanocomposite films. Accordingly, a satisfactorily higher remanent polarization was obtained than exhibited by normal PZT films, but the coercive field was only slightly higher. However, adding an excess of Pt made the nanocomposite films too leaky to exhibit the enhancement. Moreover, the nanocomposite PZT-Pt films in the capacitor configuration of Pt/LaNiO3/PZT-Pt/LaNiO3/Pt also exhibited highly reliable polarization retention and fatigue resistance.
The LaNiO3 (LNO) thin films were deposited on Si substrate by rf magnetron sputtering. The interface and electrical properties of LNO/Si contacts were investigated. For the deposition at room temperature, an amorphous LNO film with a clean interface was formed on the Si. However, a thin silicon oxide layer of approximately 2.5 nm was formed at the interface between LNO and Si after rapid thermal annealing (RTA) at temperatures ≥450 °C. On the other hand, a highly (100)-textured LNO film along with an interfacial oxide layer of approximately 6.0 nm was obtained for the deposition at 400–450 °C. Nevertheless, if an ion beam etching was applied prior to the high temperature deposition at 400–450 °C, a clean interface at the interface could be obtained for the LNO/Si contacts. Moreover, crystallites with (111) planes grown epitaxially along the (111) planes of Si were found in the LNO films. All the contacts had shown good current–voltage characteristics of a Schottky diode with a barrier height of 0.69–0.78 eV for the LNO/n-Si contacts and 0.60–0.67 eV for the LNO/p-Si contacts, and the barrier height increased with the thickening of interfacial oxide layer. From the measurement of capacitance (C) under reverse bias (Vr) of the contacts made with LNO deposited on the ion-etched Si substrates, a linear relation was observed in the plot of C−2 against Vr except a deviation of linearity in the low-bias part of the curve. This deviation is most likely due to the segregation and inward diffusion of La and Ni near the interface of LNO/Si contacts. Nevertheless, the barrier heights evaluated from an extrapolation of linear part of the plots are reasonably consistent with those obtained from the I–V measurement.
Real-time x-ray reflectivity and diffraction measurements under in situ sputtering conditions were employed to study the growth behavior of LaNiO3 thin films on a Si substrate. Our results clearly show there is a transition layer of 60 Å, which grew in the first 6 min of deposition. The in situ x-ray-diffraction patterns indicated that this transition layer is amorphous. Subsequently, a polycrystalline overlayer grew as observed from the in situ x-ray reflectivity curves and diffraction patterns. Nucleation and growth took place on this transition layer with random orientation and then the polycrystalline columnar textures of (100) and (110) grew on the top of this random orientation layer. By comparing the integrated intensities of two Bragg peaks in the plane normal of x-ray diffraction, it was found that a crossover of the growth orientation from the ⟨110⟩ to the ⟨100ߩ direction occurred and the ability of (100) texturization enhanced with increasing film thickness beyond a certain critical value.
Real-time x-ray reflectivity and diffraction measurements under in-situ sputtering deposition conditions were performed to study the crystallization behavior of LaNiO3thin films on Si substrate. We found that an amorphous layer of 60 Å was grown in the first 6 min of the deposition and subsequently a polycrystalline overlayer was developed as observed from the in-situ x-ray reflectivity curves and diffraction patterns. Polycrystalline columnar textures of (110) and (100) were grown on the top of this amorphous film. By comparing the integrated intensities of two Bragg peaks in the plane normal of x-ray diffraction, it was found that the ability of (100)-texturization enhanced with increasing film thickness over a certain critical value.
The kinetics of in situ crystallization of LaNiO3 thin films in sputtering deposition at temperatures ranging from 250 to 450 °C and isothermal crystallization of room-temperature (RT) sputtered LaNiO3 thin films in annealing at 350–500 °C were investigated by the x-ray diffraction method. The crystallization in both cases basically followed the Johnson–Mehl–Avrami (JMA) relation. However, different crystallization kinetics were observed. The transformation index and activation energy of crystallization in high temperature sputtering were about 1.5 and 33 kJ/mole, respectively, while in the annealing of RT-sputtered films, 1.0 and 63 kJ/mole were found. From the determined transformation index, it is suggested that the crystallization rate in high temperature sputtering was determined by a diffusion-controlled process of lateral growth with a decreasing nucleation rate of crystallites in the adsorption layer. However, the annealed films crystallized by an interface-controlled and one-dimensional growth of existing nuclei.
X-ray reflectivity and diffraction were applied to characterize the highly (100)-textured thin films of LaNiO3, which were deposited on Si substrate via radio frequency magnetron sputtering at temperatures ranging from 250 to 450 °C. Two interference fringes of different period were observed from the reflectivity curves, and the fitting result indicates that in addition to the normal lanthanum-nickel oxide layer, a transition layer, which has a larger mass density than the previous one, exists in the sputter-deposited films. A comparison of the measured x-ray diffraction intensity with that calculated from layer thickness and mass density obtained from reflectivity data indicates that the transition layer is noncrystalline. The x-ray diffraction result also shows that there is a significant decrease of (100) diffraction intensity relative to that of (200) as increasing the deposition temperature. Using the reflectivity and diffraction data along with results of electron diffraction and film composition analysis from our other studies, such a change of relative intensity between the two diffraction peaks is attributed to the increasing content of two also highly textured La-rich phases, i.e., (110)-textured La4Ni3O10 and (100)-textured La2NiO4, in addition to the LaNiO3.
Highly (100)-oriented thin films of PbTiO3 were prepared on (100)-textured LNO/Pt/Ti/SiO2/Si substrates by rf magnetron sputtering at temperatures ≥480 °C, while randomly oriented PbTiO3 films were obtained on Pt/Ti/SiO2/Si substrates. The textured LNO layer can help to control the orientation of PbTiO3 thin films, and reduce their surface roughness quite significantly. The dielectric constant (εT) of PbTiO3 films deposited on LNO was lower than that of films on Pt and the dielectric loss (tan δ) increased when a higher deposition temperature or longer time was used. The highly (100)-textured PbTiO3 films also showed different ferroelectric hysteresis characteristics, i.e., a higher coercive field and a lower remanent polarization, from that of randomly oriented films deposited on Pt.
Email your librarian or administrator to recommend adding this to your organisation's collection.