Unraveling Electron Dynamics in p-type Indium Phosphide (100): A Time-Resolved Two-Photon Photoemission Study

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Direct photoelectrochemical (PEC) water splitting using renewable energy is vital for future sustainable energy.
• Indium phosphide (InP) is a promising III-V semiconductor for PEC and photovoltaic (PV) applications.

Purpose of the Study:

• Investigate the electronic band structure and electron dynamics of phosphorus-terminated p-doped InP(100) (P-rich p-InP).
• Utilize time-resolved two-photon photoemission (tr-2PPE) spectroscopy to probe unoccupied conduction band states.

Main Methods:

• Time-resolved two-photon photoemission (tr-2PPE) spectroscopy.
• Analysis of electronic states near the band gap, including surface and bulk states.
• Determination of electron decay constants in conduction band states.

Main Results:

• Identified at least nine distinct electronic states in p-InP(100) between the valence band edge and vacuum energy.
• Observed a surface defect state pinning the Fermi level and six unoccupied surface resonances within the conduction band.
• Determined decay constants for five conduction band states, enabling tracking of electron relaxation.

Conclusions:

• The complex electronic band structure of p-InP(100) is characterized.
• Understanding electron dynamics is key for enhancing InP for efficient PEC hydrogen production and PV cells.
• Further surface engineering of InP-based III-V compounds can improve renewable energy technologies.