Uniaxial strain effects on the optoelectronic properties of GaN nanowires

• GaN nanowires with both uniaxial compression and stretch are discussed.
• The stability of the nanowires under uniaxial strain are compared.
• Work functions of the nanowires are calculated.
• Band structures and optical properties of GaN nanowires with different deformations are discussed.
• Uniaxial strain engineering can effectively adjust the optoelectronic properties of GaN nanowires.

Considering the importance of strain engineering on semiconductors, GaN nanowires under uniaxial compression deformation and stretch deformation are researched using first principle calculations with density functional theory. It is found that the deformation will destroy the stability of the nanowires except a weak stretch. The compression deformation is more difficult than the stretch deformation. Besides, the work function of the nanowires is reduced under increasing compression while that under increasing stretch is reversed. With increasing diameter, the band gaps of the nanowires gradually exhibit a linear decreasing relation as the elongation of uniaxial length of GaN nanowires. With increasing compression, the band gaps change from direct to indirect. The optical calculations exhibit a redshift for the imaginary part of dielectric function. This study demonstrates strain engineering can effectively adjust the optoelectronic characteristics of GaN nanowire. Moderate compression, which induces a lower work function with a direct band gap, can improve the photoemission performance of GaN nanowires.