Fabry–Perot Microcavity Modes in Single GaP/GaNP Core/Shell Nanowires

Abstract

Semiconductor nanowires (NWs) are attracting increasing interest as nanobuilding blocks for optoelectronics and photonics. A novel material system that is highly suitable for these applications are GaNP NWs. In this article, we show that individual GaP/GaNP core/shell nanowires (NWs) grown by molecular beam epitaxy on Si substrates can act as Fabry-Perot (FP) microcavities. This conclusion is based on results of microphotoluminescence (μ-PL) measurements performed on individual NWs, which reveal periodic undulations of the PL intensity that follow an expected pattern of FP cavity modes. The cavity is concluded to be formed along the NW axis with the end facets acting as reflecting mirrors. The formation of the FP modes is shown to be facilitated by an increasing index contrast with the surrounding media. Spectral dependence of the group refractive index is also determined for the studied NWs. The observation of the FP microcavity modes in the GaP/GaNP core/shell NWs can be considered as a first step toward achieving lasing in this quasidirect bandgap semiconductor in the NW geometry.

Anisotropic Radiation in Heterostructured “Emitter in a Cavity” Nanowire

“…Both spectra are found to be strongly modulated, unlike the emission collected in the vicinity of the NDs. The modulation occurs when the Fabry-Perot (F-P) resonance condition is met [50,51]. The NW edges, first, correspond to the field maxima for the standing waves, fulfilling the F-P condition, and, second, act as efficient scattering cites, which is why we observe a high-intensity modulated signal here.…”

Flexibly and Repeatedly Modulating Lasing Wavelengths in a Single Core–Shell Semiconductor Microrod

“…From Figure 2b, we find that for the core−shell nanorod with a core radius of 75 nm, the proportion decrease from 88.6% to 3.5% as the mode number increases. 22,23 However, for the core−shell microrod with a core radius of 1 μm, the proportion is 98.74% at least, as shown in Figure 2c red line. Thus, for the operation wavelength of 390 nm, the gain medium and the resonant cavity are decoupled sufficiently when the InGaN shell layer is 50 nm and the radius of GaN core reaches 1 μm.…”

“… , Since the shell has a quite small thickness, it is difficult for the InGaN shell to confine the light and support optical resonant modes. So most of the emission from the InGaN gain medium is coupled into the GaN core which acts as an optical microcavity and generates resonant modes. − When the narrow bandgap end of the InGaN shell layer is locally excited, whether the residual light in the shell layer or the main part of light coupled into the core, in the transmission of positive direction, interband optical absorption cannot take place, and the light easily reaches the threshold and starts lasing. For the other case, when the wide bandgap end of the InGaN shell layer is locally excited with the same power, the situation is different.…”

Tailoring Morphology and Vertical Yield of Self-Catalyzed GaP Nanowires on Template-Free Si Substrates

“…Small footprint and strain relaxation on sidewalls enable dislocation-free NW epitaxial growth on widely used Si substrates [ 4 ] and open up a route to combine materials with large lattice mismatch in axial or radial NW heterostructures [ 5 ]. In addition that, naturally smooth side facets allow NWs to serve as micro and nano cavities for both Fabry–Perot and whispering gallery modes [ 6 , 7 , 8 ], as well as low-loss optical waveguides [ 9 ].…”