Zhibing Zhan

MgZnO-based metal-semiconductor-metal solar-blind photodetectors on ZnO substrates

Using lattice matched ZnO substrates, wurtzite single crystalline Mg0.49Zn0.51O films were obtained by reactive magnetron cosputtering method, and the heterostructures of MgZnO/ZnO were fabricated into metal-semiconductor-metal solar-blind photodetectors (SBPDs). Calculated and experimental results demonstrate that the response of the ZnO substrate can be suppressed by adopting a thick MgZnO epilayer. The SBPD with a 2 μm thick MgZnO epilayer shows a peak responsivity of 304 mA/W at 260 nm under 10 V bias, which is comparable to the highest value ever reported in MgZnO-based SBPDs. A rejection ratio (R260 nm/R365 nm) over 5×102 is also observed, indicating fully suppression of the signal from ZnO substrate.

Ultrasonic investigation of Pd39Ni10Cu30P21 bulk metallic glass upon crystallization

Acoustic velocities of Pd39Ni10Cu30P21 bulk metallic glass (BMG) are measured by an ultrasonic technique upon annealing. The elastic constants and the Debye temperature are obtained. A large softening of the transverse phonon is exhibited in the as-quenched BMG relative to its crystallized state. Upon crystallization, the shear modulus and the Debye temperature increase by ∼30% and ∼12%, respectively; however, the density increases by only ∼0.6%. Some anomalous acoustic and elastic behaviors are observed near the glass transition temperature and in the supercooled liquid region of the BMG. The anomalies are explained with regard to the structural changes.

Elastic constants of Pd39Ni10Cu30P21 bulk metallic glass under high pressure

The pressure-dependent acoustic velocities of a Pd39Ni10Cu30P21 bulk metallic glass (BMG) have been measured up to 0.5 GPa by using an ultrasonic technique with the pulse echo overlap method. The elastic constants, the Debye temperature, and their pressure dependence are obtained. The isothermal equation of state (EOS) of the BMG is established in terms of the Murnaghan form. The atomic configurations of the BMG are discussed by comparing the elastic constants and the EOS with those of its metallic component and of other amorphous materials.The pressure-dependent acoustic velocities of a Pd39Ni10Cu30P21 bulk metallic glass (BMG) have been measured up to 0.5 GPa by using an ultrasonic technique with the pulse echo overlap method. The elastic constants, the Debye temperature, and their pressure dependence are obtained. The isothermal equation of state (EOS) of the BMG is established in terms of the Murnaghan form. The atomic configurations of the BMG are discussed by comparing the elastic constants and the EOS with those of its metallic component and of other amorphous materials.

Formation of ZrTiCuNiBe bulk metallic glass by shock-wave quenching

Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) was prepared by shock-wave quenching. Differences in property, structure, and thermal stability were found between the BMGs prepared by the shock-wave quenching and water quenching. The glass transition temperature of the shock-wave-quenched BMG is about 13K higher than that of the water-quenched one. Although the density of the shock-wave-quenched BMG is decreased, the acoustic velocities in it are increased. Shock-wave quenching is possibly a promising method for preparing BMG.

Crystallization of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass under high pressure examined by in situ synchrotron radiation x-ray diffraction

Crystallization of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass under high temperature and high pressure has been investigated by in situ synchrotron radiation x-ray diffraction. The onset temperature of crystallization was found to increase with pressure, but with a sudden drop at about 5.6GPa. Though the primarily precipitated phase is the same at different pressures, the sequences of the following phase precipitation are different.

Compression behaviour of Pd39Ni10Cu30P21 bulk metallic glass up to 23.5 GPa

The compression behaviour of a Pd39Ni10Cu30P21 bulk metallic glass is investigated at room temperature up to 23.5 GPa using in situ high pressure energy dispersive x-ray diffraction with a synchrotron radiation source. Pressure induced structural relaxation of the bulk metallic glass is exhibited within the pressure range. It is found that below about 5 GPa, the existence of excess free volume contributes to rapid structural relaxation, which gives rise to rapid volumetric change. Under higher pressure, further relaxation results in structural stiffness.