Direct Band Gap Gallium Antimony Phosphide (GaSbxP(1-x)) Alloys

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Research

Background:

• Gallium Phosphide (GaP) is an indirect band gap semiconductor.
• Achieving a direct band gap in GaP is crucial for optoelectronic applications.
• Alloying is a common strategy to tune semiconductor properties.

Purpose of the Study:

• To investigate the direct band gap transition in Gallium Phosphide (GaP) when alloyed with Antimony (Sb).
• To explore the potential of GaSbₓP₍₁₋ₓ₎ alloys for photoelectrochemical water splitting.
• To synthesize and characterize GaSbₓP₍₁₋ₓ₎ nanowires.

Main Methods:

• Density Functional Theory (DFT) based computations.
• Experimental synthesis of GaSbₓP₍₁₋ₓ₎ nanowires via reactive transport and microwave plasma discharge.
• Photoelectrochemical experiments to determine material properties.

Main Results:

• A direct band gap transition in GaSbₓP₍₁₋ₓ₎ occurs at approximately x = 0.0092 Sb incorporation.
• Calculations predict band edge straddling for hydrogen and oxygen evolution reactions from x = 0.0092 to x = 0.065 Sb.
• Synthesized nanowires (x = 0.06–0.12 Sb) exhibit direct band gaps between 2.21 eV and 1.33 eV.
• Photoelectrochemical tests confirm photoactivity and p-type conductivity.

Conclusions:

• Low concentrations of Sb (1-2 at%) induce a direct band gap in GaP.
• GaSbₓP₍₁₋ₓ₎ is a promising candidate for Schottky-type photoelectrochemical water splitting devices.
• This tunable semiconductor system offers significant potential for diverse applications.