Controllable Growth Of One Dimensional Semiconductor Nanostructures And Their Applications In Photodetectors

One dimensional semiconductor nanowires(NWs) have attracted much attention due to their unique optoelectronic property, flexibility and the ability of high- level integration. However, fabricating high-performance devices based on semiconductor NWs remains a challenge. Herein, we have fabricated single-crystal NWs with high quality by utilizing vapor phase deposition system. Also, photodetectors based on organic NW arrays or inorganic core/shell NW gained high photoresponse properties.(1) We demonstrated the high-density, large-area, uniform and cross-aligned growth of single-crystalline PTCDA NW arrays by using Au nanoparticles(NPs) on Si substrate as the growth templates. Selectivity growth of PTCDA NW arrays were achieved on Si/SiO2 substrate with pre-prepared Au electrodes, forming a NW array-based photodetectors. Photodetectors fabricated via a simple in-situ growth approach exhibited fast respond speed and high-sensitivity to a wide band light ranging from 400 nm to 800 nm. Successful applications of PTCDA NW arrays in photodetectors show a great potential application of organic NW arrays in future miniaturized, flexible and integrated photodetectors.(2) High density of Ge NWs have been fabricated in the furnace with the Au NPs as seed catalysts based on VLS mechanism. Also, Ge/CdS core/shell NWs were also obtained by directly depositing CdS film shell onto the surface of Ge NWs via atomic layer deposition(ALD) technique. The heterojunction photodetector based on single Ge/CdS core/shell NW was constructed after removing partial CdS shell and electrode deposition. Moreover, the photodetector shows high on/off ratio, fast speed and broadband photoresponse from visible to near- infrared with the bias voltage fixed at 0 V and-5V, indicating the great potential application of core/shell NW heterojunction in photodetectors with fast response speed and high responsivity.