Huaizhong Xing

Fabrication of ZnO/CdS/Cu2ZnSnS4 p–n heterostructure nanorod arrays via a solution-based route

ZnO/CdS/Cu2ZnSnS4 p–n heterostructure nanorod arrays were fabricated through a novel solution-based method using ZnO nanorod arrays as the template. Typical ZnO/CdS/Cu2ZnSnS4 heterostructure nanorod arrays consist of ZnO/CdS core/sheath nanorods and Cu2ZnSnS4 nanocrystallines grown on the primary ZnO/CdS core/sheath nanorods. In the ZnO/CdS/Cu2ZnSnS4 heterostructure nanorods arrays, ZnO core and CdS sheath are single crystalline, while Cu2ZnSnS4 nanoparticles are polycrystalline. The possible formation mechanism of ZnO/CdS/Cu2ZnSnS4 heterostructure nanorod arrays is also discussed in detail. The ZnO/CdS/Cu2ZnSnS4 heterostructure nanorod arrays possess a broad and enhanced optical absorption from the ultraviolet to the near-infrared region. A good rectification characteristic is observed in the I–V curve of ZnO/CdS/Cu2ZnSnS4 nanorod, which confirms that the ZnO/CdS/Cu2ZnSnS4 nanorod is a p–n heterostructure. Micro-Raman spectroscopy was used to investigate the vibrating properties of ZnO/CdS/Cu2ZnSnS4 heterostructure nanorod arrays. The results indicate that the ZnO/CdS/Cu2ZnSnS4 p–n heterostructure nanorod arrays may shed light on new opportunities for nanoscale optoelectronic devices.

In Situ Atom Scale Visualization of Domain Wall Dynamics in VO2 Insulator-Metal Phase Transition

A domain wall, as a device, can bring about a revolution in developing manipulation of semiconductor heterostructures devices at the atom scale. However, it is a challenge for these new devices to control domain wall motion through insulator-metal transition of correlated-electron materials. To fully understand and harness this motion, it requires visualization of domain wall dynamics in real space. Here, domain wall dynamics in VO2 insulator-metal phase transition was observed directly by in situ TEM at atom scale. Experimental results depict atom scale evolution of domain morphologies and domain wall exact positions in (202) and (040) planes referring to rutile structure at 50°C. In addition, microscopic mechanism of domain wall dynamics and accurate lattice basis vector relationship of two domains were investigated with the assistance of X-ray diffraction, ab initio calculations and image simulations. This work offers a route to atom scale tunable heterostructure device application.

Characterization of Nanostructured n-ZnO/p-Si Heterojunction Prepared by a Simple Sol–Gel Method

The nanostructured ZnO film was prepared on a texturized Si wafer by a simple sol–gel method to fabricate n-ZnO/p-Si heterojunction photoelectric device. The novel sol–gel method is cheap and convenient. The structural, optical and electrical properties of the nanostructured ZnO film were studied by XRD, SEM, XPS, PL, UV–Vis spectrophotometer and Hall effect measurement. The current–voltage (I–V) curve of nanostructured ZnO/p-Si heterojunction device shows good rectifying behavior. Good photoelectric behavior is obtained.

OBSERVATION OF NANOSPHERICAL n-SnO2/p-Si HETEROJUNCTION FABRICATED BY ULTRASONIC SPRAY PYROLYSIS TECHNIQUE

Thin film of tin oxide (SnO2) was prepared on p-type polished silicon wafer by ultrasonic spray pyrolysis technique using SnCl4 precursor solution to fabricate nanospherical n-SnO2/p-Si heterojunction photoelectric device. Deposition of film was achieved at 400°C substrate temperature. The self-made ultrasonic spray pyrolysis system is very cheap and convenient. The microstructural, optical and electrical properties of the SnO2 film were characterized by XRD, SEM, XPS, UV-VIS spectrophotometer, four point probe and Hall effect measurement, respectively. The SnO2 film has the nanospherical particles. The electrical properties of heterojunction were investigated by I–V measurement, which reveals that the heterojunction shows strong rectifying behavior under a dark condition. The ideality factor and the saturation current density of this diode are 4.27 and 2.52 × 10-6 A/cm2, respectively. And the values of IF/IR (IF and IR stand for forward and reverse current, respectively) at 5 V is found to be as high as 248. The SnO2/p-Si heterojunction device exhibits obvious photovoltaic effect. Under an AM1.5 illumination condition, the open-circuit voltage (Voc), short-circuit current density (JSC), fill factor (FF) of the device are 150 mV, 3.9 × 10-3 mA/cm2 and 20.58%, respectively. High photocurrent is obtained under a reverse bias when the crystalline quality of SnO2 film is good enough to transmit the light into p-Si. Under 6.3 mW/cm2 illumination, when the reverse bias is -5 V, the photocurrent gain is as high as 86.

Preparation and optoelectrical properties of p-CuO/n-Si heterojunction by a simple sol-gel method

The Cuprous oxide (CuO) thin film was prepared on texturized Si wafer by a simple sol–gel method to fabricate p-CuO/n-Si heterojunction photoelectric device. The novel sol–gel method is very cheap ...