Characterization of Fabry-Pérot microcavity modes in GaAs nanowires fabricated by selective-area metal organic vapor phase epitaxy

Abstract

The authors present the formation of Fabry-Pérot cavity in single GaAs nanowire prepared by selective-area metal organic vapor phase epitaxy. The grown nanowires with hexagonal cross section are highly uniform and vertically oriented. Microphotoluminescence measurements of single GaAs nanowire exhibit periodic peaks in the intensity, which are suggestive of the longitudinal modes of a Fabry-Pérot cavity. The cavity is formed along the length of the nanowire and the ͑111͒ facets of both ends act as reflecting mirrors. Additionally, optical waveguides in GaAs nanowires were also observed. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2787895͔ Semiconductor nanowires have been attracting great interests because they are potentially used as building blocks in nanoelectronics and photonics. [1][2][3][4] Recently, semiconductor nanolasers working in ultraviolet region based on ZnO ͑Ref. 3͒ and CdS͑Ref. 4͒ single nanowires were reported. These applications require that the fabricated nanowires should be uniform and flat enough to form Fabry-Pérot cavities. We recently proposed and demonstrated an alternative method of preparing semiconductor nanowires by using selective-area metal organic vapor phase epitaxy ͑SA-MOVPE͒. 5-8 Compared to the conventional vapor-liquid-solid growth, 9,10 this is a catalyst-free approach and only relies on the thermal decomposition of source materials. Furthermore, since this method fully utilizes the nature of epitaxial growth, it is expected to exhibit superior crystalline quality as well as good controllability of the growth with atomic precision to form abrupt doping profiles and heterojunctions, including vertical and lateral heterostructures. [6][7][8] In this letter, we fabricated GaAs nanowires with uniform and smooth surfaces by SA-MOVPE. Microphotoluminescence ͑ PL͒ measurements reveal the formation of Fabry-Pérot cavity modes in individual GaAs nanowires, caused by the refractive index difference between the wire and the surrounding. Thus, GaAs nanowires may be candidate materials for achieving stimulated emission or lasing, especially in near-infrared region.SA-MOVPE growth of GaAs nanowires started with the deposition of 30 nm SiO 2 layer by plasma sputtering on ͑111͒B GaAs substrate. Then SiO 2 was partially removed by electron beam lithography and wet chemical etching. The mask pattern of SiO 2 had circular opening and they were arranged in a triangular lattice. The diameter of the grown nanowires was directly related to that of the opening holes. In addition, we controlled the nanowire length by adjusting the opening pitch and growth condition. Finally, the patterned substrates were loaded into a horizontal low-pressure MOVPE system working at 0.1 atm using trimethylgallium ͑TMG͒ and arsine ͑AsH 3 ͒ as source materials. Typical partial pressures were 9.6ϫ 10 −7 and 2.5ϫ 10 −4 atm for TMG and AsH 3 , respectively. The growth temperature and growth time for GaAs nanowires were 750°C and 60 min. Typical freestanding GaAs nanowires grown on ͑111͒B GaAs substrate by MOVPE...

Resonant cavity modes in gallium oxide microwires

“…Fabry-Perot (FP) modulations due to reflections between wire flat ends and whispering gallery modes (WGMs) due to total internal reflections in microstructures with regular polyhedral cross-sections were reported in some semiconducting micro and nanostructures. FP resonant modes from near band edge transitions have been reported in GaN, 1,2 GaAs, 3 and ZnO (Refs. 4 and 5) nanowires.…”

“…In particular, luminescence and waveguiding properties of single nanowires have been reported in view of their applications as lasers or efficient optical cavities in photonic devices. [1][2][3][4][5][6][7][8][9][10][11][12] The high crystalline quality and the commonly flat surfaces of nanowires are valuable points to consider them very good candidates to explore their behavior as optical resonators. Fabry-Perot (FP) modulations due to reflections between wire flat ends and whispering gallery modes (WGMs) due to total internal reflections in microstructures with regular polyhedral cross-sections were reported in some semiconducting micro and nanostructures.…”

Lasing from individual GaAs-AlGaAs core-shell nanowires up to room temperature

“…The end-facet reflectivity (B0.6) is sufficient to reach transparency in NWs with a length of a few micrometres by engineering the confinement of the optical mode via their diameter 7,13 . However, the deleterious impact of non-radiative surface and Auger recombination has limited progress in the technologically important near-infrared spectral range, although lasing is predicted to be within the reach of GaAs NWs with sufficiently high crystalline quality and lengths exceeding a few micrometres 13,20 .…”

Nanowire Optoelectronics

“…For subwavelength structures, the longitudinal WGM have high scattering losses because of diffraction, and axial FP waveguide modes will dominate [90]. However, because of small difference in the refractive index between the substrate and the NW dielectric, the existence of the FP mode will only be valid if the NWs have relatively large radii, for example, larger than 200 nm [101]. Under these conditions, besides the top and bottom ends, the lateral facets of NW can also be treated as two parallel slabs, and with the dielectric in between, it can support the FP mode with mode spacing inversely related to the NW length.…”