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The polarization effect introduced by electric field deformation is the most important bottleneck of CdZnTe detector in x-ray imaging. Currently, most of studies focus on electric field deformation caused by trapped carriers; the perturbation of electric field due to drifting carriers has been rarely reported. In this study, the effect of transient space–charge perturbation on carrier transport in a CdZnTe semiconductor is evaluated by using the laser-beam-induced current (LBIC) technique. Cusps appear in the current curves of CdZnTe detectors with different carrier transport performances under intense excitation, indicating the deformation of electric field. The current signals under different excitations are compared. The results suggest that with the increase of excitation, the amplitude of cusp increases and the electron transient time gradually decreases. The distortion in electric field is independent of carrier transport performance of detector. Transient space–charge perturbation is responsible for the pulse shape and affects the carrier transport process.

Cu/HfOx/n+Si devices are fabricated to investigate the influence of technological parameters including film thickness and Ar/O2 ratio on the resistive switching (RS) characteristics of HfOx films, in terms of switch ratio, endurance properties, retention time and multilevel storage. It is revealed that the RS characteristics show strong dependence on technological parameters mainly by altering the defects (oxygen vacancies) in the film. The sample with thickness of 20 nm and Ar/O2 ratio of 12:3 exhibits the best RS behavior with the potential of multilevel storage. The conduction mechanism of all the films is interpreted based on the filamentary model.

Resistive switching characteristics of hafnium oxide are studied for possible nonvolatile memory device applications. The HfOx films with different oxygen contents are deposited by rf magnetron sputtering under different O2 flow rates. The films are amorphous, and the stoichiometric of the film is improved by increasing the O2 flow rate. Current-voltage characteristics of the TiN/HfOx/ITO device are investigated with 1 mA compliance. The bipolar resistive switching behavior is observed for the TiN/HfOx/ITO structure, and the resistive switching mechanism of the TiN/HfOx/ITO structure is explained by trap-controlled space charge limit current conduction.

The structural, electronic and mechanical properties of cubic SrHfO3 under hydrostatic pressure up to 70 GPa are investigated using the first-principles density functional theory (DFT). The calculated lattice parameter, elastic constants and mechanical properties of cubic SrHfO3 at zero pressure are in good agreement with the available experimental data and other calculational values. As pressure increases, cubic SrHfO3 will change from an indirect band gap (Γ–R) compound to a direct band gap (Γ–Γ) compound. Charge densities reveal the coexistence of covalent bonding and ionic bonding in cubic SrHfO3. With the increase of pressure, both the covalent bonding (HfO) and ionic bonding (SrO) are strengthened. Cubic SrHfO3 is mechanically stable when pressure is lower than 55.1 GPa, whereas that is instable when pressure is higher than 55.1 GPa. With the increasing pressure, enthalpy, bulk modulus, shear modulus and Young's modulus increase, whereas the lattice parameter decreases. Moreover, cubic SrHfO3 under pressure has higher hardness and better ductility than that at zero pressure.