Research On Electrical Transport Properties Of Tellurium Nanowires

Tellurium is an important semiconductor material and its band gap is 0.34 e V. The compound nanomaterials of Te are important semiconducting materials with excellent physical and chemical properties,which make them promising candidates of various applications, including optoelectronic devices and biomedical field. This thesis chooses tellurium nanowires as the subject to research its property of electrical transport and optical ectrical properties. The research results are listed as follows:1. Tellurium nanowires was synthesized by hydrothermal method in this thesis, its diameter was 80-200 nm with the characteristics of well Monodisperse, high purity and good crystallinity. The Te nanowires was characterized by XRD and SEM. The XRD pattern taken from the nanowires shows a strong [101] diffraction peak, possibly owing to the growth of Te nanowires along the [101] direction.2. The individual Te nanowire devices with the structure of metal/Te nanowire /metal has been fabricated with standard photolithography technique and lift-off process.3. The Te nanowires devices were tested in the air and vacuum at room temperature. A perfect ohmic contact between electrode and the nanowire was achieved. The field effect characteristic shows that the Te nanodevice is a typical P type semiconductor with hole carrier mobility750 cm2v-1s-1, as the leakage current(Ids) of nanodevices is decreased with the decrease of the gate pressure(Vgs). The With the increase of relative humidity, the number of water molecules adsorbes on the surface of Te nanowires is increased, therefore, the number of electrons adsorbed on the surface of Te nanowires can be increased. The surface potential of the nanowires is decreased, which has been attracted more holes to the surface layer. Thus the conductance of the tellurium nanowire can be increased.4. Negative photoconductivity was first investigated in the Te nanowires, i.e., the conductivity of the nanowires under light was dramatically lower than that in the dark. Photoproduction electronics are adsorbed on the surface of the nanowires, then the electronics are compounded with the hole of itself, which caused the reduction of the inside hole carrier concentration of tellurium nanowires. so the conductance of the nanowires is decrease.In the future, we hope to testing the time response of tellurium nanowires in the vacuum, we can further verify the above negative photoconductive mechanism of tellurium nanowires. Through the controllable preparation of tellurium nanowires, we can provide an ideal template for the preparation of CdTe, Ag2 Te and Bi2Te3 functional materials.