Carrier Transport in GaAs Nanowires Using Surface Acoustic Waves
- PDF / 276,626 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 27 Downloads / 246 Views
Carrier Transport in GaAs Nanowires Using Surface Acoustic Waves A. Hernández-Mínguez1, M. Möller2, C. Pfüller1, S. Breuer1, O. Brandt1, M. M. de Lima, Jr. 2, A. García-Cristóbal2, A. Cantarero2, L. Geelhaar1, H. Riechert1 and P. V. Santos1 1 Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany 2 Institut de Ciència dels Materials, Universitat de València, E-46071 València, Spain ABSTRACT The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited electrons and holes in GaAs nanowires (NWs) transferred to a SAW beam line on a LiNbO3 crystal. We show that carriers generated in the NW by a focused light spot can be acoustically transported to a second location, where they recombine emitting short light pulses. The results presented here demonstrate the high-frequency manipulation of carriers in NWs without the use of electrical contacts, which opens new perspectives for applications in opto-electronic devices operating at GHz frequencies. INTRODUCTION Semiconductor nanowires (NWs) offer new possibilities for low-dimensional semiconductor devices [1,2]. Their small cross-section favors mesoscopic size effects and allows material combinations that are normally impossible to obtain in two-dimensional epitaxial growth. In addition, their special geometry provides new concepts for opto-electronic devices. Several obstacles need to be overcome for the full exploitation of these favorable features. One of them is the need for appropriate techniques for applying electrical control fields, which typically requires doping as well as contacting of nm-sized structures with non-planar geometry. In this contribution, we demonstrate that this obstacle can be overcome by using surface acoustic waves (SAWs) to remotely control carriers in GaAs/(Al,Ga)As core-shell NWs. SAWs are propagating elastic vibrations confined to the surface of a material. On a piezoelectric semiconductor, these vibrations are accompanied by a piezoelectric potential )SAW, which traps electrons and holes in spatially separated positions, preventing their recombination while transporting them with the well-defined SAW velocity [3]. SAWs have proven to be a powerful tool to confine and transport free single carriers [4] as well as spin ensembles [5-7] in 2D semiconductor heterostructures. The evanescent )SAW extends to approximately one acoustic wavelength both below and above the surface, so it can also be employed for carrier control in hybrid systems consisting of a semiconductor structure placed on a piezoelectric substrate. This approach was used to transport electrically injected carriers in carbon nanotubes [8-10] and in NWs [11], as well as to locally modulate their photoluminescence (PL) [12,13]. We show here that the SAWs, apart from remotely control the PL intensity [13] and provide information about the electronic properties of NWs [14], can also transport photoexcited carriers along the NW. EXPERIMENT The NWs were grown by molecular beam epitaxy (MBE) using a self-assi
Data Loading...
