Accession Number : AD1020602


Title :   Micro-Photoluminescence (micro-PL) Study of Core-Shell GaAs/GaAsSb Nanowires Grown by Self-Assisted Molecular Beam Epitaxy


Descriptive Note : Technical Report


Corporate Author : North Carolina A and T State University Greensboro United States


Personal Author(s) : Shifat,M D ; Sami,U S


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/1020602.pdf


Report Date : 18 Jun 2015


Pagination or Media Count : 81


Abstract : III-V NWs stand out due to their exceptional high electron mobility. The ability to grow in both axial and core-shell configurations in conjunction with band gap tuning as in the 2D structure make the NWs very attractive for next generation photo-detector, field-effect transistor (FET) and light emitting diode (LED) applications. In this thesis, room temperature and low temperature (4K) micro-photoluminescence (micro-PL) spectra of GaAs/GaAsSb ensemble NWs of single core-shell and double-shell configurations grown by molecular beam epitaxy will be presented. Experimental setup variables, namely detector type, objective lens magnification and chopper frequency on micro-PL of these NWs were carefully examined to arrive at the optimized set up. Effect of Sb composition on the micro-PL spectra was studied. The dominant 4K PL peak varied from 1.35 eV to 0.99 eV with Sb concentration varying from 3 at.% to 26 at.%. The intensity dependence of micro-PL spectra at 4K enabled the development of band gap alignment in these structures. With increase in Sb composition type II hetero-alignment transitioned to type I alignment. NWs are observed to be curved with increasing Sb composition, which is attributed to the increased strain. PL system was suitably modified to acquire micro-PL spectra from a single NW. The system was made user friendly by adding a suitable attachment exterior to the optical system that facilitated motion of the laser in the nm range. micro-PL spectra of single NW replicated very well the respective NW ensemble, indicative of good compositional homogeneity of the NWs constituting the ensemble. Thus these NWs are very promising for near infrared optoelectronic device applications.


Descriptors :   PHOTOLUMINESCENCE , MOLECULAR BEAM EPITAXY , NANOWIRES , optoelectronic devices , semiconductors , band gaps , solid state physics


Subject Categories : Solid State Physics


Distribution Statement : APPROVED FOR PUBLIC RELEASE