Growth characteristics of uniaxial InGaN/GaN MQW/n-GaN nanowires on Si(111) using MOCVD

We report on the growth of the uniaxial InGaN/GaN multiple quantum well (MQW) on n-GaN nanowires (NWs) on Si(111) substrates by dynamically adjusting the growth parameters using the pulsed flow metalorganic chemical vapor deposition (MOCVD) technique. We carried out a two-step growth process to grow the uniaxial InGaN/GaN MQW/n-GaN NWs structure. In the first step, the n-GaN NWs were grown at 950 degrees C and in the second stage, we suitably decreased the growth temperature to 630 and 710 degrees C, respectively, to grow InGaN/GaN MQW NWs. The surface morphology, structural and optical characterization of the grown InGaN/GaN MQW/n-GaN NWs were studied by field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), photoluminescence (PL) and cathodoluminescence (CL) measurements. The CL spectrum recorded on an individual InGaN/GaN MQW/n-GaN NW is dominated by the band-edge emission at 366.7 and 413.5 nm corresponding to n-GaN and MQW structures, respectively. The resultant NWs were found to be free of strain. These results indicate that the pulsed MOCVD technique is an effective method to grow uniaxial InGaN/GaN MQW on n-GaN NWs which is advantageous to other growth techniques. These kinds of uniaxial NWs are promising to allow flat band quantum structures that are shown to improve the efficiency of light-emitting diodes.