Strain engineering as one of the most powerful techniques for tuning optical and electronic properties of III-nitrides requires reliable methods for strain investigation.In this work,we reveal,that the linear model ba...Strain engineering as one of the most powerful techniques for tuning optical and electronic properties of III-nitrides requires reliable methods for strain investigation.In this work,we reveal,that the linear model based on the experimental data limited to within a small range of biaxial strains(<0.2%),which is widely used for the non-destructive Raman study of strain with nanometer-scale spatial resolution is not valid for the binary wurtzite-structure group-III nitrides GaN and AlN.Importantly,we found that the discrepancy between the experimental values of strain and those calculated via Raman spectroscopy increases as the strain in both GaN and AlN increases.Herein,a new model has been developed to describe the strain-induced Raman frequency shift in GaN and AlN for a wide range of biaxial strains(up to 2.5%).Finally,we proposed a new approach to correlate the Raman frequency shift and strain,which is based on the lattice coherency in the epitaxial layers of superlattice structures and can be used for a wide range of materials.展开更多
基金the U.S.National Science Foundation Engineering Research Center for Power Optimization of Electro Thermal Systems(POETS)with cooperative agreement EEC-1449548F.M.O.and M.D.T.acknowledge the financial support of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasil(CAPES)-Finance Code 001.
文摘Strain engineering as one of the most powerful techniques for tuning optical and electronic properties of III-nitrides requires reliable methods for strain investigation.In this work,we reveal,that the linear model based on the experimental data limited to within a small range of biaxial strains(<0.2%),which is widely used for the non-destructive Raman study of strain with nanometer-scale spatial resolution is not valid for the binary wurtzite-structure group-III nitrides GaN and AlN.Importantly,we found that the discrepancy between the experimental values of strain and those calculated via Raman spectroscopy increases as the strain in both GaN and AlN increases.Herein,a new model has been developed to describe the strain-induced Raman frequency shift in GaN and AlN for a wide range of biaxial strains(up to 2.5%).Finally,we proposed a new approach to correlate the Raman frequency shift and strain,which is based on the lattice coherency in the epitaxial layers of superlattice structures and can be used for a wide range of materials.
