Optical Properties of Strained Wurtzite Gallium Phosphide Nanowires

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Wurtzite gallium phosphide (WZ GaP) is predicted to have a direct bandgap in the green spectrum.
• Optical transitions in WZ GaP are weakly allowed due to band symmetry.
• The exact nature of efficient luminescence in WZ GaP remains unclear.

Purpose of the Study:

• To investigate the influence of tensile strain on WZ GaP nanowire photoluminescence.
• To determine the nature and symmetry of optical transitions in WZ GaP.
• To clarify the role of localized states versus the conduction band minimum in WZ GaP emission.

Main Methods:

• Applying tensile strain up to 6% to WZ GaP nanowires.
• Analyzing photoluminescence (PL) spectrum evolution under strain.
• Investigating pressure and polarization dependence of emission.
• Conducting theoretical analysis of strain effects on band structure.

Main Results:

• Emission lines are identified as originating from localized states with significant Γ7c symmetry admixture.
• The conduction band minimum (CBM), specifically Γ8c, is not the sole contributor to emission.
• Strain significantly influences the photoluminescence spectrum and transition symmetry.

Conclusions:

• Luminescence in WZ GaP is strongly influenced by localized states, not just the CBM.
• Understanding these localized states is crucial for WZ GaP optoelectronic applications.
• This study significantly advances the knowledge of WZ GaP's optical properties.