Light absorption properties of a nanowire/quantum-dot hybrid nanostructure array

The light absorption properties of a nanowire/quantum-dot hybrid nanostructure array are investigated. By growing multilayer InAs quantum dots on the sidewalls of GaAs nanowires, not only the absorption spectrum of GaAs nanowires is extended by quantum dots, but also the light absorption of quantum dots is dramatically enhanced due to the light-trapping effect of the nanowire array. By optimizing the nanowire and quantum dot parameters, a maximum photocurrent increment of 2.8 mA/cm2 is obtained by incorporating 5 layer InAs quantum dots into a 3 μm high GaAs nanowire array, 4.6 times of its thin-film counterpart. Mode analysis demonstrates that the fundamental mode in the nanowire has a dominate influence on the QD absorption in the wavelength range beyond GaAs bandgap.