研究目的
Comparing the e?ciency droop of InGaN multiple-quantum-well (MQW) blue light-emitting diode (LED) structures grown on silicon(111) and c-plane sapphire substrates and analyzing the e?ciency droop characteristics using the rate equation model with reduced e?ective active volume.
研究成果
The efficiency droop of the LED on silicon was considerably lower than that of the LED on sapphire, attributed to its larger effective active volume resulting from the lower internal electric field. The reduced effective active volume was due to the combined effect of both the reduced active width of a single QW and the reduced effective number of QWs in MQW layers as a result of the internal electric field.
研究不足
The study is limited by the uncertainty in the reported C coefficient values and the assumption that the B and C coefficients are the same for LEDs on silicon and sapphire substrates. Additionally, the influence of indium composition fluctuation inside InGaN QWs on the effective active volume was not extensively explored.
1：Experimental Design and Method Selection:
The study involved comparing the efficiency droop characteristics of InGaN MQW blue LED structures grown on silicon(111) and c-plane sapphire substrates using the rate equation model with reduced effective active volume.
2：Sample Selection and Data Sources:
LED samples were fabricated on both silicon and sapphire substrates, with identical active layer structures and indium composition in the QWs.
3：List of Experimental Equipment and Materials:
Metal-organic chemical vapor deposition was used for epitaxial layer growth, and LED chips were fabricated as vertical current injection structures.
4：Experimental Procedures and Operational Workflow:
Electroluminescence measurements were conducted inside an integrated sphere with temperature control, and pulsed currents were applied to reduce self-heating effects.
5：Data Analysis Methods:
The external quantum efficiency (EQE) versus current relation was analyzed using the ABC rate equation model to determine the effective active volume and internal quantum efficiency (IQE).
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