Strain-Induced Band Gap Engineering in Selectively Grown GaN-(Al,Ga)N Core-Shell Nanowire Heterostructures

We demonstrate the selective area growth of GaN-(Al,Ga)N core shell nanowire heterostructures directly on Si(111). Photoluminescence spectroscopy on as-grown nanowires reveals a strong blueshift of the GaN band gap from 3.40 to 3.64 eV at room temperature. Raman measurements relate this shift to compressive strain within the GaN core. On the nanoscale, cathodoluminescence spectroscopy and scanning transmission electron microscopy prove the homogeneity of strain-related luminescence along the nanowire axis and the absence of significant fluctuations within the shell, respectively. A comparison of the experimental findings with numerical simulations indicates the absence of a significant defect-related strain relaxation for all investigated structures, with a maximum compressive strain of -3.4% for a shell thickness of 50 nm. The accurate control of the nanowire dimensions, namely, core diameter, shell thickness, and nanowire period, via selective area growth allows a specific manipulation of the resulting strain within individual nanowires on the same sample. This, in turn, enables a spatially resolved adjustment of the GaN band gap with an energy range of 240 meV in a one-step growth process.


Published in:
Nano Letters, 16, 11, 7098-7106
Year:
2016
Publisher:
Washington, American Chemical Society
ISSN:
1530-6984
Keywords:
Laboratories:




 Record created 2017-01-24, last modified 2018-09-13

n/a:
Download fulltext
PDF

Rate this document:

Rate this document:
1
2
3
 
(Not yet reviewed)