Ion-beam irradiation(IB) on HfO2 surface induced high-performance liquidcrystal(LC) driving at a 1-V threshold with vertical alignment of liquid crystals(LC). The high-k materials Atomic layer deposition was used to obtain LC orientation on ultra thin and high-quality films of HfO2 layers. To analyze surface morphological transition of HfO2 which can act as physic alignment effect of LC, atomic force micro scopy images are employed with various IB intensities. The contact angle was measured to elucidate the mechanism of vertical alignment of LC on HfO2 with IB irradiation. Contact angle measurements show the surface energy changes via IB intensity increasing.

The electrical and interfacial properties of HfO2/Al2O3 and Al2O3/HfO2 dielectrics on AlN/p-Ge interface prepared by thermal atomic layer deposition are investigated by capacitance–voltage(C–V) and current–voltage(I–V) measurements. In the C–V measurements, humps related to mid-gap states are observed when the ac frequency is below 100 kHz, revealing lower mid-gap states for the HfO2/Al2O3 sample. Higher frequency dispersion in the inversion region is observed for the Al2O3/HfO2 sample, indicating the presence of slow interface states A higher interface trap density calculated from the high-low frequency method is observed for the Al2O3/HfO2 sample. The parallel conductance method, applied to the accumulation region, shows border traps at 0.3~0.32 eV for the Al2O3/HfO2 sample, which are not observed for the Al2O3/HfO2 sample. I–V measurements show a reduction of leakage current of about three orders of magnitude for the HfO2/Al2O3 sample. Using the Fowler-Nordheim emission, the barrier height is calculated and found to be about 1.08 eV for the HfO2/Al2O3 sample. Based on these results, it is suggested that HfO2/Al2O3 is a better dielectric stack than Al2O3/HfO2 on AlN/p-Ge interface.

In this study, we used I-V spectroscopy, photoconductivity (PC) yield and internal photoemission (IPE) yield using IPE spectroscopy to characterize the Schottky barrier heights (SBH) at insulator-semiconductor interfaces of Pt/HfO2/p-type Si metal-insulator-semiconductor (MIS) capacitors. The leakage current characteristics of the MIS capacitor were analyzed according to the J-V and C-V curves. The leakage current behavior of the capacitors, which depends on the applied electric field, can be described using the Poole-Frenkel (P-F) emission, trap assisted tunneling (TAT), and direct tunneling (DT) models. The leakage current transport mechanism is controlled by the trap level energy depth of HfO2. In order to further study the SBH and the electronic tunneling mechanism, the internal photoemission (IPE) yield was measured and analyzed. We obtained the SBH values of the Pt/HfO2/p-type Si for use in Fowler plots in the square and cubic root IPE yield spectra curves. At the Pt/HfO2/p-type Si interface, the SBH difference, which depends on the electrical potential, is related to (1) the work function (WF) difference and between the Pt and p-type Si and (2) the sub-gap defect state features (density and energy) in the given dielectric.

Calcia (CaO) stabilized cubic-HfO2 is studied by density functional theory (DFT) with generalized gradient approximation (GGA). When a Ca atom is substituted for a Hf atom, an oxygen vacancy is produced to satisfy the charge neutrality. The lattice parameter of a 2×2×2 cubic HfO2 supercell then increases by 0.02 Å. The oxygen atoms closest to the oxygen vacancy are attracted to the vacancy as the vacancy is positive compared to the oxygen ion. When the oxygen vacancy is located at the site closest to the Ca atom, the total energy of HfO2 reaches its minimum. The energy barriers for the migration of the oxygen vacancy were calculated. The energy barriers between the first and the second nearest sites, the second and the third nearest sites, and the third and fourth nearest sites are 0.2, 0.5, and 0.24 eV, respectively. The oxygen vacancies at the third and fourth nearest sites relative to the Ca atom represent the oxygen vacancies in undoped HfO2. Therefore, the energy barrier for oxygen migration in the HfO2 gate dielectric is 0.24 eV, which can explain the origin of gate dielectric leakage.

A new cost-effective atomic layer deposition (ALD) technique, known as Proximity-Scan ALD (PS-ALD) was developed and its benefits were demonstrated by depositing Al2O3 and HfO2 thin films using TMA and TEMAHf, respectively, as precursors. The system is consisted of two separate injectors for precursors and reactants that are placed near a heated substrate at a proximity of less than 1 cm. The bell-shaped injector chamber separated but close to the substrate forms a local chamber, maintaining higher pressure compared to the rest of chamber. Therefore, a system configuration with a rotating substrate gives the typical sequential deposition process of ALD under a continuous source flow without the need for gas switching. As the pressure required for the deposition is achieved in a small local volume, the need for an expensive metal organic (MO) source is reduced by a factor of approximately 100 concerning the volume ratio of local to total chambers. Under an optimized deposition condition, the deposition rates of Al2O3 and HfO2 were 1.3 Å/cycle and 0.75 Å/cycle, respectively, with dielectric constants of 9.4 and 23. A relatively short cycle time (5~10 sec) due to the lack of the time-consuming "purging and pumping" process and the capability of multi-wafer processing of the proposed technology offer a very high through-put in addition to a lower cost.