研究目的
Investigating the dynamics of a coupled system of free and localized carriers in semiconductors with strong carrier localization and its influence on photoluminescence properties.
研究成果
The efficiency droop effect in AlGaN quantum wells is caused by peculiarities of carrier localization without significant influence of Auger recombination. The model and simulation procedures are applicable for analysis of carrier dynamics in any materials where localized and free carriers coexist.
研究不足
The model requires many material parameters and several assumptions on the processes of importance. The simulations are limited by the complexity of the carrier dynamics in the localizing potential and the need for accurate fitting of experimental data.
1：Experimental Design and Method Selection:
Kinetic Monte Carlo technique is used for simulations to model the dynamics of free and localized carriers.
2：Sample Selection and Data Sources:
AlGaN/AlGaN multiple quantum wells (MQWs) structure grown by migration-enhanced metalorganic chemical vapor deposition (MEMOCVD?) technique on a c-plane sapphire substrate.
3：List of Experimental Equipment and Materials:
A closed-cycle helium cryostat, a double monochromator (Jobin Yvon HRD-1), and a UV-enhanced photomultiplier for PL measurements.
4：Experimental Procedures and Operational Workflow:
PL spectra were measured under excitation power density varied from
5：4 kW/cm2 to 14 MW/cm2 at different temperatures from 8 K to 300 K. Data Analysis Methods:
The PL efficiency was calculated as the ratio of spectrally-integrated PL intensity and excitation power density.
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