High-Quality Uniaxial In_xGa_1–xN/GaN Multiple Quantum Well (MQW) Nanowires (NWs) on Si(111) Grown by Metal-Organic Chemical Vapor Deposition (MOCVD) and Light-Emitting Diode (LED) Fabrication

This article describes the growth and device characteristics of vertically aligned high-quality uniaxial p-GaN/InxGa1-xN/GaN multiple quantum wells (MQW)/n-GaN nanowires (NWs) on Si(111) substrates grown by metal-organic chemical vapor deposition (MOCVD) technique. The resultant nanowires (NWs), with a diameter of 200-250 nm, have an average length of 2 μm. The feasibility of growing high-quality NWs with well-controlled indium composition MQW structure is demonstrated. These resultant NWs grown on Si(111) substrates were utilized for fabricating vertical-type light-emitting diodes (LEDs). The steep and intense photoluminescence (PL) and cathodoluminescence (CL) spectra are observed, based on the strain-free NWs on Si(111) substrates. High-resolution transmission electron microscopy (HR-TEM) analysis revealed that the MQW NWs are grown along the c-plane with uniform thickness. The current-voltage (I-V) characteristics of these NWs exhibited typical p-n junction LEDs and showed a sharp onset voltage at 2.75 V in the forward bias. The output power is linearly increased with increasing current. The result indicates that the pulsed MOCVD technique is an effective method to grow uniaxial p-GaN/InxGa1-xN/GaN MQW/n-GaN NWs on Si(111), which is more advantageous than other growth techniques, such as molecular beam epitaxy. These results suggest the uniaxial NWs are promising to allow flat-band quantum structures, which can enhance the efficiency of LEDs.