The Synthesis And Photodetective Characteristics Of Both Individual InP Nanowires And Their Planar Arrays

In the past decades,indium phosphide(InP),as a very impotant III–V material,has gain much attention due to its exceptional optical and electronic properties.Numbers of previous reports have demonstrated its promising applications such as the high electron mobility transistors,photovoltaic cells,photodetectors and so on.Compared with bulk and film materials,one–dimensional InP structures possess higher surface–to–volumer ratio which would facilitate the transport of the carrier along the axis of the wires and therefore improve the performance in optoelectronic devices.Herein,we used a slightly improved chemical vapor deposition(CVD)method for the synthesis of freestanding and planarly aligned InP nanowires with high quality.Then we carried out systematic researches on the microstructures,optical and electric properties as well as photodetective performances of these nanostructures.The main results are summarized as follows:(1)High density InP nanowires with clean surface and diameter fell in the range of 20–40 nm were grown on Si substrates utilizing improved Au–assisted CVD route.XRD and TEM measurements of nanowires demonstrated that the as–grown materials had high crystal quality and were mainly in zinc–blende(ZB)phase.Room–temperature PL and Raman spectra further confirmed the high quality of InP nanowires which makes it available for manufacturing high–performance optical and electric devices.(2)Using high precision EBL technology,we fabricated single InP NW field–effect transistors(FETs)with the common back –gated configuration which exhibited a typical n–type semiconducting behavior and a high electronic mobility found to be 212 cm2/V·s.In situ photodetective characterizations of individual nanowires were carried out under illumination of 520 nm laser.The devices demonstrated outstanding light sensing performances: a responsivity of 4.2 × 103 A/W,external quantum efficiency of 1 × 106%,?r = 70 ms,and ?d = 120 ms,which can rival or even surpass the previous results.(3)We successfully grew plenty of planar InP nanowire arrays on annealed M–plane sapphire substrates by CVD method.The morphology characterizations showed that nanowires had smooth surfaces and good parallel alignment and follow ed the graphoepitaxial growth mechanism which is named guided growth.PL and Raman spectra showed that the crystallinity of planar nanowires did not suffer any degeneration as compared with the conventional ones.The photodetectors based on aligned InP NW arrays showed both outstanding EQE value and photoresponse speed that can rival thier conventional counterparts.