研究目的
To study the surface potentials and carrier behavior at V-pit and U-pit defects in GaN using UV light-assisted KPFM, and to understand the variation of surface potentials and electron concentrations with and without UV light illumination.
研究成果
The surface potentials and electron concentrations at V-pit and U-pit defects in GaN are uneven, with higher recombination rates at pit defects compared to planar surfaces. UV light-assisted KPFM is an effective method for studying carrier behavior, providing insights for optimizing GaN-based optoelectronic devices.
研究不足
The study is limited to specific types of pit defects (V-pits and U-pits) on GaN surfaces and may not generalize to other defect types or materials. The use of KPFM and assumptions in band models could introduce measurement uncertainties. The research focuses on carrier behavior under controlled laboratory conditions and may not fully capture real-world device performance.
1：Experimental Design and Method Selection:
The study uses UV light-assisted Kelvin probe force microscopy (KPFM) to measure surface potentials at pit defects on GaN surfaces. Band structure models are established to interpret the results.
2：Sample Selection and Data Sources:
A GaN sample grown by metal organic chemical vapor deposition (MOCVD) on a c-plane sapphire substrate is used, with pit density of about
3：9×10^6 cm^-List of Experimental Equipment and Materials:
AFM (Bruker MultiMode-8 tapping mode), SEM (HITACHI S-4800), KPFM (Bruker MultiMode-8 surface potential mode), MESP model tip (radius 35 nm, elastic coefficient 1-5 N/m), scanner model AS-130VLR ('J' vertical).
4：Experimental Procedures and Operational Workflow:
Surface morphologies are characterized by AFM and SEM. Surface potentials are measured in dark and under UV light using KPFM. Section profiles are analyzed to determine electron concentrations.
5：Data Analysis Methods:
Electron concentrations are calculated using equations based on surface potential differences and Boltzmann statistics. Non-equilibrium electron concentrations are derived to infer carrier recombination rates.
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