Optical absorption of composition-tunable InGaAs nanowire arrays.
Nanotechnology
; 30(49): 495703, 2019 Dec 06.
Article
em En
| MEDLINE
| ID: mdl-31469097
ABSTRACT
InGaAs nanowire (NW) arrays have emerged as important active materials in future photovoltaic and photodetector applications, due to their excellent electronic properties and tunable band gap. Here, we report a systematic investigation of the optical absorption characteristics of composition-tunable vertical InGaAs NW arrays. Using finite-difference time-domain simulations we first study the effect of variable composition (Ga-molar fraction) and NW array geometry (NW diameter, period, fill factor) on the optical generation rate. NWs with typical diameters in the range of â¼100-250 nm lead to generation rates higher than the equivalent bulk case for moderate fill factors (NW period of â¼0.3-0.8 µm), while slightly smaller fill factors and increased diameters are required to maintain high generation rates at increased Ga-molar fraction. The optical absorption was further measured using spectrally resolved ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy on NW arrays transferred to transparent substrates. Interestingly, large variations in Ga-molar fraction (0 < x(Ga) < 0.5) have a negligible influence, while minute changes in NW diameter of less than ±20 nm affect the absorption spectra very strongly, leading to pronounced shifts in the peak absorption energies by more than â¼700 meV. These results clearly highlight the much larger sensitivity of the optical absorption behavior to geometric parameters rather than to variations in the electronic band gap of the underlying NW array.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Nanotechnology
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Alemanha