Development of InGaN/GaN nanostructures

by Carla Ivana Oppo
Doctoral thesis
Date of Examination:2017-01-31
Date of issue:2017-02-06
Advisor:Prof. Dr. Angela Rizzi
Referee:Prof. Dr. Angela Rizzi
Referee:Prof. Dr. Hans Christian Hofsäss
Persistent Address: http://dx.doi.org/10.53846/goediss-6110

 

 

Files in this item

Name:OppoThesis.pdf
Size:30.0Mb
Format:PDF

The following license files are associated with this item:

Abstract

English

In this work, the mechanisms regulating the selective area growth (SAG) of GaN-based nanostructures have been investigated, under different growth conditions, with the aim of improving the control over the growth of InGaN/GaN heterostructures.  First of all, starting from the knowledge already acquired in the group concerning the growth of GaN arrays on Molybdenum mask, the morphological evolution of GaN SAG nanostructures, grown on Mo and Ti mask, has been further investigated, as a function of the nominal fluxes ratio, as well as as a function of the growth time and the lithographed nanohole dimensions.  Once the mechanisms behind the SAG of GaN nanostructures have been better understood, the additional growth of epitaxial InGaN on the semipolar tip of the SAG nanostructures has been investigated and different InGaN growth approaches have been considered to this scope.  Finally, the attention has been turned to the disordered self-induced nanocolumns, accidentally grown on the Mo mask during the SAG of InGaN/GaN nanostructures.  Due to the need of high spatial resolution and high chemical sensitivity analytical techniques, the characterization of InGaN/GaN nanostructures has been performed by means of different analytical techniques, in particular: SEM chatodoluminescence (SEM-CL) analysis, nano X-ray fluorescence (nano-XRF) and diffraction (nano-XRD), high-angle annular dark-field scanning trans- mission electron microscopy (HAADF-STEM) and high-resolution transmission electron microscopy (HR-TEM).
Keywords: molecular beam epitaxy; InGaN/GaN; nanocolumns; selective area growth; polarity; semipolar; x-ray fluorescence; x-ray diffraction; cathodoluminescence
 
Statistik