Fabrication and Characterization of III-V Nanowires

Semiconductor nanowires (NWs) are of both large fundamental and technological interest and have generated enormous interest in the past few years. These free-standing NWs are usually obtained by epitaxial growth on semiconductor surfaces with predeposited metal nanoparticles. The metal nanoparticles alloy with the semiconductor and the NW growth is catalyzed at the interface between the metal nanoparticle and the semiconductor. This results in the formation of "bottom-up" grown vertical NWs on top of which the alloyed particle segregates. The NW diameter is fixed by the size of the metal particles but typical sizes range in the order of 20 - 100 nanometers in diameter with a few micrometers in length depending on growth conditions.

So far most semiconductor NWs have been grown by either metal-organic vapor phase epitaxy (MOVPE) or chemical vapor deposition (CVD). In contrast NW growth by molecular beam epitaxy (MBE) is much less explored. MBE grown NWs could have many advantages due to stronger nonequilibrium conditions and growth at lower substrate temperatures.

We intend to fabricate and characterize III-V NWs by Au-assisted vapor-liquid-solid (VLS) MBE growth.[1] The long term goal is to fabricate and process AlGaSbAs based heterostructure NWs for nano-photonic applications in the near infra-red wavelength region. If single NWs can be successfully grown and processed into laser diodes, detectors and sensors, a large market in different areas of nano-optoelectronics and nano-sensing is expected.

Reference : 1. R.S. Wagner and W.C. Ellis, Appl. Phys. Lett. 4 (1964) 89.