Shell to core carrier-transfer in MBE-grown GaAs/AlGaAs core–shell nanowires on Si(100) substrates

• Published in: Journal of luminescence Vol. 155; pp. 27 - 31
• Main Authors: Balgos, Maria Herminia, Jaculbia, Rafael, Defensor, Michael, Afalla, Jessica Pauline, Ibañes, Jasher John, Bailon-Somintac, Michelle, Estacio, Elmer, Salvador, Arnel, Somintac, Armando
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2014; Elsevier
• Subjects: Carrier transfer; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; III–V semiconductors; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Nanoscale materials and structures: fabrication and characterization; Nanowires; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics; Quantum wires; Time-resolved luminescence; III–V semiconductors; Time-resolved luminescence; Nanowires; Carrier transfer; Temperature dependence; Gallium arsenides; Blende structure; Core shell structure; Ternary compounds; Photoluminescence; Time resolved spectra; Time resolution; Aluminium Arsenides; Energy gap; Time resolved spectroscopy; Traps; Ionization; Rate equation; Molecular beam epitaxy; ps range; III-V semiconductors
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2014.06.008

We report on the shell-to-core carrier-transfer in GaAs/Al0.1Ga0.9As core-shell nanowires grown on Si(100) substrates via molecular beam epitaxy. The nanowires are dominantly zincblende and are tilted with respect to the substrate surface. Photoluminescence (PL) excitation spectrosocopy at 77K revealed an abrupt increase in the GaAs PL intensity at excitation above the Al0.1Ga0.9As shell bandgap which is attributed to shell to core carrier-transfer. More carriers from the Al0.1Ga0.9As transfer to the GaAs at T>90K, as observed in the time-resolved PL and temperature dependence of the relative PL intensities of GaAs and Al0.1Ga0.9As due to the ionization of the traps within the Al0.1Ga0.9As. Using a coupled rate equation model that takes into account shell to core carrier-transfer, the average recombination time constants of Al0.1Ga0.9As shell τrec,s=400ps (580ps) and GaAs core τrec,c=600ps (970ps) were obtained from the time-resolved PL at 300K (77K). Carrier-transfer time constants τCT=50ps (55ps) at 300K (77K) were also obtained. •Evidence of shell to core carrier transfer is observed via photoluminescence.•A rate equation model was modified to account for the carrier transfer.•Analysis showed that the carrier transfer is more favored at temperatures >90K.