Macroporous p-GaP Photocathodes Prepared by Anodic Etching and Atomic Layer Deposition Doping

Area of Science:

• Materials Science
• Electrochemistry
• Semiconductor Physics

Background:

• Gallium phosphide (GaP) is a promising semiconductor for photoelectrochemical applications.
• Developing efficient doping methods for high-aspect ratio III-V materials remains a challenge.

Purpose of the Study:

• To develop a controllable doping strategy for creating p-type macroporous GaP photoelectrodes.
• To investigate the photoelectrochemical properties of Zn-doped macroporous GaP.

Main Methods:

• Anodic etching of n-type GaP(100) wafers to create macroporous structures.
• Conformal coating of GaP with 30 nm zinc oxide (ZnO) films using atomic layer deposition (ALD).
• Drive-in doping of GaP with zinc (Zn) via annealing at 650 °C.

Main Results:

• Zn-doped macroporous GaP exhibited strong cathodic photocurrent under white light illumination.
• Photoresponse measurements showed enhanced collection efficiency at wavelengths > 460 nm.
• The ALD doping method successfully rendered the GaP material p-type, enabling a strong internal electric field.

Conclusions:

• Atomic layer deposition (ALD) of ZnO provides a practical and controllable dopant source for Zn in GaP.
• This method is effective for doping high-aspect ratio III-V semiconductor materials.
• The resulting p-type macroporous GaP photoelectrodes show significant potential for photoelectrochemical applications.