The optical absorption in zincblende and wurtzite GaP nanowire polytypes

The geometry dependence of the absorption in semiconductor nanowires is of large interest currently, and especially the diameter-dependent absorption resonances are promising for tunable detectors. Here, we show that these resonances for both wurtzite and zincblende GaP nanowires can be tuned down to λ ~ 330 nm by decreasing the diameter to 35 nm. This stop of the shifting at λ ~ 330 nm indicates that both polytypes show a critical point in the refractive index in this region of the ultra violet regime. This similarity of the resonant response in both polytypes of GaP nanowires is in strong contrast to the case of InP and InAs nanowires.