The Study Of GaAs Axial Heterostructure Nanowires

This research was mainly supported by the National Basic Research Program of China (2010CB327600), the National Natural Science Foundation of China (61020106007 and 61077049), New Century Excellent Talents in University (NCET-08-0736), and the 111 Program of China (B07005).In recent years, semiconductor nanowires have become the hotspot in the world due to its unique physical properties. A lot of devices based on nanowires including FETs lasers, and photodetectors have come out, which show broad application prospects. Heterostructure is the base of semiconductor devices and almost all of the new progress in semiconductor devices are associated with the heterojuncture. This paper mainly focuses on GaAs axial heterostructure nanowires. The main research content and achievements are as follows:1. The status and prospects of research on the growth mechanism, characterization methods and GaAs heterostructure nanowires were reviewed.2. GaAs/InxGa1-xAs/GaAs double-heterostructure nanowire were grown on GaAs(111) substrate by low-pressur metal organic chemical vapor deposition(LP-MOCVD). The influence of indium content on the morphology and structure of nanowires was studied. Experimental results indicated that almost all the nanowires were kinked when indium content was 0.8; GaAs nanowires can be grown on In As nanowires while InAs nanowires can not be grown on GaAs nanowires due a lower interfacial energy between Au and GaAs as well as easier incorporiton of In atoms into the Au particle.3. Vertical GaAs/InxGa1-xAs/InAs heterostructure nanowires and GaAs/InxGa1-xAs/InAs/GaAs heterostructure nanowires were successfully grown on GaAs(111) substrate. The critical radius of nanowireswas analysed. The strain of nanowire with a section of composition-graded buffer segment was discussed. Results indicated that by inserting a composition-graded InxGa1-xAs buffer segment between GaAs and InAs, high yield of straight GaAs/InxGa1-xAs/GaAs heterostructrue nanowires were realized. Lattice parameter varies linearly and the influence of strain on the growth of nanowires could be eliminated. In addition, the restrict of interfacial energy in epitaxial growth of nanowire heterostructures was proved.