Core/Shell CdS:Ga/ZnTe:Sb P-n Nanostructure: Fabrication And Optoelectronic Characteristics

II-VI Group materials such as ZnO, ZnSe, CdS, ZnTe are direct band gap semiconductors with band gap covering from UV to visible light. They have important applications in photodetector, photovoltaic and luminescent devices. P-n junction is one of the most fundamental building blocks for the construction of advanced electronic and optoelectronic devices at nanoscale level. Because it is difficult to achieve p-type CdS, the attempt to fabricate p-n junction only with CdS is very difficult for self-compensation effect. Studies showed that CdS (bandgap:2.4eV) could only exist n-type conduction behavior in thermodynamic equilibrium. Zinc telluride (bandgap: 2.26eV) is also a member of the Ⅱ-Ⅵ group materials. It is naturally p-type and chemical stable with high transmittance. A combination of both CdS and ZnTe provides a novel idea to solve the problem of building p-n junction device only with single polarity conductive CdS material.There are p-n nano-junctions with various structures. P-n junction of core-shell structure is more noticeable for its high aspect ratio. So far, there are many methods to fabricate core-shell p-n junction, including selective area metalorganic vapor phase epitaxy, chemical vapor deposition, hydrotherm method, and atomic layer deposition and so on. And the optoelectronic devices based on core-shell p-n junction showed excellent performance, especially in photodetector. While there are still very little work on core-shell p-n junction with controlled doping and optoelectronic performance.The main content of this thesis is about the synthesis of CdS:Ga/ZnTe:Sb core-shell nano-structure by a two-step CVD method. The photodetector of core-shell p-n junction was fabricated by three steps photolithography technique and its optoelectronic performance was studied also. The synthesized CdS:Ga nanowires are single-crystal structure with growth direction of [100] and its absorption edge red shifted to about 580nm after wrapped polycrystalline shell of ZnTe, compared to CdS:Ga nanowires (520nm). And the absorption area of core-shell structure became wide. The responsivity and detectivity of photodetector based on core-shell p-n junction are estimated to be 1.55×103 AW- and 8.7×1012 cmHz1/2W-1 under 638 nm light irradiation. The responsivity and detectivity are much higher than other materials with similar structures.