Papers by Author: Hai Ping He

Abstract: In this study, the authors have presented results for fabricated ZnO based FET and the UV-photoconductive characteristics of Na doped ZnMgO thin films. The electrical measurements confirmed that the conductivity of the Na doped ZnMgO thin film is p-type, and the carrier mobility was estimated to be 2.3 cm2V-1S-1. Moreover, after exposed to the 365 nm ultraviolet light, the Na doped ZnMgO thin films still exhibited p-type behavior under gate voltage ranging from -5 to 2 V, and the Id increased a little while the carrier mobility did not change much. The photocurrent was measured under a bias of 6 V in air at room temperature. The films performed a higher current intensity after the illumination. The instantaneous rise of the photocurrent was completed when exposed to the 365 nm ultraviolet for 20 s, after switching the ultraviolet off the photocurrent decayed in a slower rate. The enhance rate of photocurrent was about 1.33 %. Conclusively, Na is a considerable acceptor dopant for making high quality p-type ZnO films, and the tiny change in the photocurrent of p-type Na doped ZnMgO thin film made it relatively stable when fabricating LEDs and other optoelectronic devices.

Abstract: ZnO microrods were synthesized on Si (111) sustrate by thermal evaporation at the temperature of 700 °C. Different growth environments bring to the different morphologies of the depositions. By analyzing the scanning electrical microscopy (SEM) images, a growth mechanism of the microrods is schematically put forward. Transmission electronic microscopy (TEM) images show that the perfectly epitaxial relationship between the ZnO nanorods and microrods.

Abstract: In this paper, a novel spinning-inflated-ballonet polishing tool for curved surface of mould is proposed. The head of the tool is a spherical spinning-inflated-ballonet whose inner air pressure can be controlled on-line and the head surface is covered with a suitable polishing cloth. The head can be rotated in high speed driven by an electromotor or high pressure airflow and its rotating speed can be adjusted. The flexibility of the head, the polishing force in radial direction and the contact area between the head surface and the curved surface of the work-piece can be controlled by adjusting the feeding deepness and ballonet pressure of the tool. The structure and the polishing mechanism of the novel polishing tool are introduced. The application of robot polishing system based on the novel polishing tool also is discussed. Finally the polishing control strategy of curved surface is researched.

Abstract: In the field of the mold-curved free surface polishing, how to control the removing depth of the polishing surface exactly is one of the important problems to be solved. In this paper, a mould automatic polishing system that is developed on Motoman-NL20 robot is used to make theoretical analysis and experimental research on the removing depth of the polishing surface based on a novel Spinning-Inflated-ballonet Polishing tool for curved surface of mould. Firstly, FEM (finite element analysis) software is used to emulate three kinds of situation in the process of polishing, then the model of surface removing depth of SBCT polishing is established. At last, through the analysis and comparison, the result of emulation and experiment has a remarkable consistency which accords with the model established by formal theory. This indicates the correctness of the model.