GaN/ZnO Nanotube Heterostructure Light-Emitting Diodes Fabricated on Si

We report the fabrication and luminescent characteristics of GaN-based visible light-emitting diode (LED) arrays on Si substrates. For the fabrication of the LEDs, high-quality GaN/ZnO coaxial nanotube heterostructures were prepared by the heteroepitaxial growth of GaN layers on position-controlled ZnO nanotube arrays grown on 1-μm-thick crack-free GaN/Si substrates. The nanostructured LEDs were composed of GaN-based p-n homojunction with GaN/In_1-xGaxN multiple quantum wells (MQWs) coaxially coated on GaN/ZnO nanotube heterostructures. The fabricated micro-LEDs emitted visible green light that originated from the MQWs of individual coaxial LEDs. In addition, the origin of the light emission was investigated by measuring cathodoluminescence and electroluminescence spectra.