Fabrication of ZnO Nanoneedle/nanocolumn Composite Films and Annealing Induced Improvement in Their Microstructural and Photoluminescence Characteristics

ZnO nanoneedle/nanocolumn （NN/NC） composite films were grown via reactive electron beam evaporation （REBE） in the NH3/H2 gaseous mixture by using polycrystalline ZnO ceramic targets as source materials. The growth was performed at low substrate temperatures （450～500℃） without employing any metallic catalysts. As-prepared samples were then rapidly annealed in 02 ambient at a higher temperature （600℃）. Electron microscopic observations revealed the typical composite-structured morphologies of NN/NC/substrate of ZnO nanomaterials grown at 500℃. Such unique morphologies should render potential applications, for instance, as an efficient microwave absorption material utilized in the fabrication of concealed aerostat. In addition, X-ray diffraction and photoluminescence measurements showed remarkable improvement in crystal and optical qualities of ZnO NN/NC composite films after annealing.

Ultrabroadband and multiband infrared/terahertz photodetectors with high sensitivity

Broadband response is pursued in both infrared(IR)and terahertz(THz)detection technologies,which find their applications in both terrestrial and astronomical realms.Herein,we report an ultrabroadband and multiband IR/THz detector based on blocked-impurity-band detecting principle.The detectors are prepared by implanting phosphorus into germanium(Ge:P),where photoresponses with a P impurity band,a self-interstitial defect band,and a vacancy-P(V-P)pair defect band are realized simultaneously.The response spectra of the detectors show ultrabroad and dual response bands in a range of 3-28μm(IR band)and 40-165μm(THz band),respectively.Additionally,a tiny mid-IR(MIR)band within 3-4.2μm is embedded in the IR band.The THz band arises from the P impurity band,whereas the IR and the MIR bands are ascribed to the two defect bands.At150 m V and 4.5 K,the peak detectivities of the three bands are obtained as 2.9×10^(12) Jones(at 3.9μm),6.8×10^(12) Jones(at 16.3μm),and 9.9×10^(12) Jones(at 116.5μm),respectively.The impressive coverage andsensitivity of the detectors are promising for applications in IR and THz detection technologies.

Electrochemical capacitance-voltage characterization of plasma-doped ultra-shallow junctions

Ultra-shallow Si p^(+)n junctions formed by plasma doping are characterized by electrochemical capacitance-voltage(ECV).By comparing ECV results with those of secondary ion mass spectroscopy(SIMS),it is found that the dopant concentration profiles in heavily-doped p+layer as well as junction depths measured by ECV are in good agreement with those measured by SIMS.However,the ECV measurement of dopant concentration in the underlying lightly doped n-type substrate is significantly influenced by the upper heavily-doped layer.The ECV technique is also easy to control and reproduce.The ECV results of ultra-shallow junctions(USJ)formed by plasma doping followed by different annealing processes show that ECV is capable of reliably characterizing a Si USJ with junction depth as low as 10 nm,and dopant concentration up to 10^(21) cm^(-3).Also,its depth resolution can be as fine as 1 nm.Therefore,it shows great potential in application for characterizing USJ in the sub-65 nm technology node CMOS devices.