Strong quantum confinement in ordered PbSe nanowire arrays
- PDF / 214,317 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 70 Downloads / 178 Views
Ordered PbSe crystalline nanowire arrays have been successfully fabricated in the nanochannels of porous anodic alumina membrane by direct current electrodeposition. X-ray diffraction and selected area electron diffraction investigations demonstrate that the PbSe nanowires have a uniform cubic structure. Electromicroscopy results show that the nanowires are quite ordered with diameters of about 50 nm and lengths up to 5 micrometers. X-ray energy dispersion analysis indicate that Pb:Se is very close to 1:1. The optical absorption spectrum of these PbSe nanowires show that there exist two peaks at 280 and 434 nm, respectively, attribute to excitonic absorption peaks.
I. INTRODUCTION
Electronic and optical properties of semiconductor nanostructures have recently attracted much attention due to their interesting physical nature and potential utility for applications.1,2 Many researchers of II-VI3,4,5, or III-V6 semiconductors have been carried out. Compared to these materials, IV-VI semiconductors such as PbSe or PbS have a large exciton Bohr radius (46 nm for PbSe and 18 nm for PbS).7 Thus, in PbSe or PbS nanostructures a large strong-confinement effect that can be expected, which cannot be accessed in other materials. In addition to physical interest, PbSe is a narrow band gap photoconductor used in infrared applications,8 and its dots are interesting for technology applications because their absorption peak position is tunable in the 1â3 âŪm range, depending on their radius. Saturated absorption for infrared lasers by using PbSe dots were demonstrated.9 There are reports on the fabrication of PbSe thin films by chemical bath deposition,10 molecular beam expitaxy,11 vacuum deposition,12 electrodeposition,13,14,15 etc. Less work has been done for PbSe nanowires, especially for ordered PbSe nanowire arrays. Due to their uniform and nearly parallel porous structures, the anodic alumina membrane (AAM) has been used as template for fabricating Ni,16 Co,17 Bi,18 and ZnO,19 CdS,3,4 and CdSe5 nanowire arrays by electrodeposition and GaN nanowire arrays by chemical vapor deposition (CVD).16 However, the electrochemical deposition method, in contrast to other deposition methods like CVD, is very simple and efficient, and during the electrodeposition
a)
Address all correspondence to this author. e-mail: [email protected] J. Mater. Res., Vol. 17, No. 6, Jun 2002
process the growth of nanowires starts at the pore tips and continues in the pore direction from the bottom to the pore opening. In the present work, we fabricated ordered PbSe nanowire arrays with diameters of about 50 nm embedded in the parallel nanochannels of the anodic anumina membrane by electrodeposition from Pb(EDTA)2â and HSeO3â precursors via total six-electron reduction reaction.14 The optical absorption spectrum of these PbSe nanowires reveals that two excitonic peaks exist at 280 and 434 nm. II. EXPERIMENT
The through hole AAM with channel diameters of about 50 nm was produced through the method similar to Ref. 20. A gold film was deposited by vacuum
Data Loading...
