Ultraviolet electroluminescence emission from n-type ZnO/p-type Si crossed nanowire light-emitting diodes

The optical characteristics of an n-type ZnO/p-type Si crossed nanowire (NW) light-emitting diode (LED) were investigated in this study. N-ZnO nanowires (NWs) were synthesized by thermal chemical vapor deposition, and p-Si NWs were fabricated by etching a single crystalline Si wafer. The p-n heterojunction LED formed by the cross of the n-ZnO and p-Si NWs selected from the NWs prepared in this work exhibited the current rectifying behavior with the turn-on voltage of 1.3 V. Our investigation of the photoluminescence spectrum of the as-grown n-ZnO NWs and electroluminescence spectrum of the n-ZnO/p-Si crossed NW LED reveals that both spectra have the same position of peaks at 390 nm. This result indicates that the UV emission from the crossed NW LED is mostly attributed to the band-to-band transition of electrons in the ZnO NW.