Vapor-Phase Synthesis Of Metal Pnictide Semiconductor Nanowires And Their Applications For Nano-Electronic&Photonic Devices

In this thesis, synthesis and characterization of one dimensional metal pnictide semiconductor nanomaterials were systematically studied. By a chemical vapor deposition process, high-quality one dimensional metal pnictide semiconductors, such as Zn3As2、InP、 Cd3P2nanowires and pearl-like GaP nanowires, were prepared successfully in a conventional horizontal furnace with a25mm inner diameter quartz tube. Metal pnictide semiconductor nanowires based optoelectronic devices, such as field effect transistors and photodetectors, were fabricated on rigid (SiO3/Si) substrate and flexible substrate (PET、 PDMS or common sellotape). And the properties of the corresponding devices were investigated. The main contents are described as follows:1. Single-crystalline Zn3AS2nanowires with the diameters of100～240nm and length of several tens of micrometers were successfully synthesized for the first time via a simple chemical vapor deposition method. Single NW FETs exhibited typical p-type transistor characteristics with the features of high mobility of305.5cm V-1s-1and a high Ion/Ioff ratio of～105. The single NW photodetector on SiO2/Si substrate showed a good sensitivity to visible light. Besides, TFTs and photodetectors built on aligned Zn3As2NW arrays on rigid SiO2/Si substrate and flexible PET substrate, produced by the simple contact printing process, were also fabricated, showing comparable performance. What is more, The NW arrays photodetectors on rigid SiO2/Si substrate and flexible PET substrate exhibited an enhanced optoelectronic performance compared with the single NW devices. Flexible Zn3As2NW arrays photodetector shows a fast response, excellent flexibility and electrical stability.The results revealed that the p-type Zn3As2NWs have important applications for future electronic and optoelectronic devices applications.2. High-quality metal pnictide semiconductors (InP and GaP) NWs were fabricated via a simple thermal evaporation method. Individual InP NW field-effect transistors (FETs) were fabricated to study its electronic transport and photoresponse characteristics, which exhibited typical n-type transistor characteristics with the efficient electron mobility of1.21cm V-1s-1, a fast response time (～0.1s) and good sensitivity with a spectral responsivity of779.14A W-1and high quantum efficiency of1.53×105%to visible light irradiation. Using contact printing process, photodetectors based on aligned InP and GaP NW arrays were fabricated on rigid SiO2/Si and PET substrate, respectively. Both the rigid and the flexible devices exhibited excellent photoresponse performance to visible light. In addition, flexible photodetectors based on aligned InP and GaP NW arrays displayed an extreme flexibility, good folding endurance and electrical stability, and are sensitive to visible lights. However, compared with the aligned (InP or GaP) NW arrays device on rigid SiO2/Si substrate, the flexible device measured at the identical condition has much lower photocurrent, which is usually attributed to the worse contact between NW and the flexible substrate compared with rigid SiO2/Si substrate.3. High-quality, pearl-like GaP nanowires consisted of the Gap trunks (diameter of～150nm) wrapped with the GaP bulbs (diameter of100～400nm) were successfully synthesized for the first time via a facile CVD method. Single pearl-like NW FETs were fabricated, exhibiting typical p-type semiconductor characteristics with the threshold voltage (Vth) of3.4V and On/Off ratio of～102. Furthermore, hybrid organic-inorganic heterojunction photodetectors based on n-type phenyl-C61-butyric acid methyl ester (PCBM) and p-type GaP NWs hybrid film were constructed on rigid SiO2/i substrate to study their photoresponse properties. Compared with the devices made of pure GaP NWs and PCBM, the hybrid device exhibited an enhanced photoresponse characteristic such as a fast response (43ms), increased photocurrent and high photoresponse ration (on/off ratio～170). Intriguingly, hybrid photodetectors have been fabricated on flexible substrates, such as PET, common sellotape and PDMS. And the flexible hybrid devices are characterized under different bending condition, revealing excellent flexibility, good folding strength and high electrical stability and high sensitivity to visible light. The high performance and flexibility of the hybrid photodetectors are promising for further large-scale, high sensitivity and high speed photodetector applications.4. Single-crystalline Cd3P2nanowires were synthesized via a CVD method to fabricate high performance nanowire photodetectors with broad spectrum response ranging from UV to infrared regions. It was discovered that the as-grown Cd3P2nanowires exhibited typical p-type semiconductor behavior with an electron mobility of2.94cm V-1s-1, capacitance of4.0×10-16F and a broad spectrum detection ranging from UV-Visible to NIR (300nm to1300nm) with high photoconductive gain (1.4×103～5.9×104A W-1), stability and reproducibility. Furthermore, hybrid organic-inorganic n-type phenyl-C61-butyric acid methyl ester (PCBM) and p-type Cd3P2NW heterojunction photodetectors on rigid SiO2/Si substrate and flexible PET substrate were also fabricated, showing fast, reversible and stable photoresponse properties with a broad spectral photoresponse ranging from UV-visible to near infrared regions. And the hybrid device exhibited much improved photocurrent and photoconductive gain, as compared to the device made of pristine Cd3P2NWs. Meanwhile, the hybrid photodetectors have also been fabricated on plastic substrates demonstrating excellent flexibility and good electrical stability.