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External Control of GaN Band Bending Using Phosphonate Self-Assembled Monolayers
Thomas Auzelle1, Florian Ullrich2,3, Sebastian Hietzschold2,4
1Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117 Berlin, Germany.
ACS Applied Materials & Interfaces
|January 13, 2021
Summary
Functionalizing gallium nitride (GaN) surfaces with phosphonic acids modifies optoelectronic properties. This surface engineering impacts band bending and quantum efficiency, showing potential for selective sensing applications.
Area of Science:
- Materials Science
- Surface Chemistry
- Optoelectronics
Background:
- Gallium nitride (GaN) is a key semiconductor for optoelectronic devices.
- Surface functionalization is crucial for tuning GaN properties.
- Understanding surface interactions is vital for advanced applications.
Purpose of the Study:
- To investigate the optoelectronic properties of GaN surfaces functionalized with phosphonic acids.
- To analyze the correlation between acid electronegativity and GaN surface band bending.
- To explore the impact of functionalization on GaN nanowires and layers.
Main Methods:
- Grafting of n-octylphosphonic acid (OPA) and perfluorooctanephosphonic acid (PFOPA) on GaN surfaces.
- Investigation using X-ray photoemission spectroscopy (XPS) and photoluminescence (PL) spectroscopy.
- Analysis of hybrid inorganic/organic heterostructures.
Main Results:
- Phosphonic acid grafting significantly alters GaN work function and surface band bending.
- Electronegativity dependence observed on oxidized GaN(11̅00) surfaces.
- Internal quantum efficiency is notably affected, especially in GaN nanowires.
Conclusions:
- Phosphonate chemistry offers effective surface functionalization for GaN.
- Surface modification impacts optoelectronic properties by altering electric fields and surface states.
- This approach holds promise for developing selective GaN-based sensors.
