Strain Engineering of Nanowire Multi-Quantum Well Demonstrated by Raman Spectroscopy

• DOI: 10.1021/nl401306q
• Publication Date: 2013-09-03T16:16:12Z
• Authors: Martin Wölz; Manfred Ramsteiner; Vladimir M. Kaganer; Oliver Brandt; Lutz Geelhaar; Henning Riechert
• Keywords: 0103 physical sciences; 02 engineering and technology; 0210 nano-technology; 01 natural sciences

An analysis of the strain in an axial nanowire superlattice shows that the dominating strain state can be defined arbitrarily between unstrained and maximum mismatch strain by choosing the segment height ratios. We give experimental evidence for a successful strain design in series of GaN nanowire ensembles with axial InxGa1-xN quantum wells. We vary the barrier thickness and determine the strain state of the quantum wells by Raman spectroscopy. A detailed calculation of the strain distribution and LO phonon frequency shift shows that a uniform in-plane lattice constant in the nanowire segments satisfactorily describes the resonant Raman spectra, although in reality the three-dimensional strain profile at the periphery of the quantum wells is complex. Our strain analysis is applicable beyond the InxGa1-xN/GaN system under study, and we derive universal rules for strain engineering in nanowire heterostructures.