| As a representative of II-VI materials,CdS has been researched extensively due to their excellent electrical and optical properties.In this paper,a microelectronic device based on the tin doped CdS comb-like structures was fabricated by Focused Ion Beam technology(FIB).Different types of multi-channel optical micro circuits were constructed based on the special geometric dimensions of CdS nanocomb.The resistivity of comb-like structure with different structural parameters in the darkness and lightness,the spectral response and the temperature dependence electronic transport properties were also investigated.An easy operation and low cost laser direct writing system was designed based on the principle of laser direct writing.And the photodetector based on a nanowire or nanobelt were fabricated successfully.The study results of electrical properties and the simple fabrication method,which laid the foundation for the construction of multi-channel array optoelectronic devices in the future.This is beneficial to the development the array devices from the measurement of synthesis and properties of materials to the device.The detail studies are listed as follows:(1)Microelectronic devices based on tin doped CdS with uniform ordered branches had been fabricated by FIB technique,which shows a typical metal-semiconductor-metal structure.The ohmic contact between different electrodes is induced by the bombardment of gallium ion during the fabricated process.An unsaturated I-V under dark condition was observed,which is owing to the influence of Schottky Barrier,the tunneling and image force.(2)The electrical properties of two comb-like structures with an acicular and uniform branch were studied,respectively.The linear relationship between the resistance and junctions with different contact electrodes was observed.Furthermore,I-V results of different multi-branch nanostructures reveal that the resistivity(resistance)can be coarsely controlled from 1.439 to 0.09??cm(1.139M? to 0.0496M?)under dark-field and fine adjustment from 0.222 to 0.069??cm(0.172M? to 0.0386M?)under bright-field,which promise potential applications of comb-like microstructure in variable resistors.(3)The wide spectrum response,especially 405 nm and 532 nm shows the excellent photoresponse properties.The time resolved photoresponse with four paralleled branches shows a fast and slow decay time.The above result is useful to the construction of multi-channel photoelectric detector array.(4)To further investigate the electrical properties at low temperature,the temperature dependent conductance curves in darkness and lightness were measured.The test was finished by the low temperature stage combined with a semiconductor testing system.The conductance was increased with the increasing temperature under the dark environment.The variation tendency of conductance was measured in lightness is different from the result that measured in darkness.The result provided a chance to construct a micro-zone temperature sensor based on the micro-comb.An anomaly phenomenon that the suppression of conductance around zero bias can be seen clearly.On the one hand,due to the impact of Schottky Barrier,the whole voltage can be divided into two parts: the voltage of the contact between the Pt electrode and CdS micro-comb,the voltage of the inherent comb-like structure.The electrical transport should overcome the obstacle of Schottky barrier at low bias.On the other hand,the strong Coulomb interaction between different electrons leads to a Coulomb gap occurs in the density of localized states,which means the depletion of the differential conductance at low energies.(5)Based on the principle of laser direct writing,a feasible method was designed to construct the electrodes,which is consist with the ultraviolet LED array and microscope system.A photodetector based on the nanowire or nanobelt have been constructed,the light-to-dark currents ration is about 150,the photosensitivity is 145. |
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