Influence of V-pits on the electro-optical properties of high-periodicity InGaN MQWs

Marco Nicoletto; Alessandro Caria; Fabiana Rampazzo; Carlo De Santi; Matteo Buffolo; Giovanna Mura; Francesca Rossi; Xuanqi Huang; Houqiang Fu; Hong Chen; Yuji Zhao; Gaudenzio Meneghesso; Enrico Zanoni; Matteo Meneghini

doi:10.1117/12.3004922

8 March 2024 Influence of V-pits on the electro-optical properties of high-periodicity InGaN MQWs

Marco Nicoletto, Alessandro Caria, Fabiana Rampazzo, Carlo De Santi, Matteo Buffolo, Giovanna Mura, Francesca Rossi, Xuanqi Huang, Houqiang Fu, Hong Chen, Yuji Zhao, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini

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Proceedings Volume 12886, Gallium Nitride Materials and Devices XIX; 128860C (2024) https://doi.org/10.1117/12.3004922
Event: SPIE OPTO, 2024, San Francisco, California, United States

Abstract

We investigated the influence of V-pits on the turn-on voltage of GaN-based high periodicity multiple quantum wells (MQWs) solar cells with different thickness of the p-GaN layer. Experimental current-voltage characteristics indicate that the sample with the thinnest p-GaN layer presents an early turn-on, which is not present for samples with a thicker p-GaN layer. Focusing on the V-defects analysis, through scanning electron microscopy (SEM) we found no difference in the density and dimensions of V-pits between sample with different p-GaN thickness. Through TCAD Synopsys Sentaurus simulations, the main non-illuminated current-voltage characteristics are reproduced considering V-defects. The results indicate that V-pits play a dominant role in current conduction, especially for the devices with the thinnest p-GaN layer due to the insufficient V-pit planarization. For such devices V-pits penetrate the junctions, and locally put the MQWs region in closer connection to the p-side contact, resulting in the formation of localized short circuit paths. Finally, a Gaussian distribution of V-pits dimensions and depth is considered to reach a good matching of experimental data. Based on combined electrical analysis, microscopy investigation and 2D simulations, results provide insight on the role of V-pits on the electrical performance of GaN-based MQWs solar cells. The outcome of this work will be useful for the design of future high-periodicity quantum wells devices, ensuring the desired turn-on voltage and showing the existence of a trade-off between the need of a thin p-GaN (to increase short-wavelength efficiency) and a thicker p-GaN, to avoid insufficient V-pit planarization.

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Marco Nicoletto, Alessandro Caria, Fabiana Rampazzo, Carlo De Santi, Matteo Buffolo, Giovanna Mura, Francesca Rossi, Xuanqi Huang, Houqiang Fu, Hong Chen, Yuji Zhao, Gaudenzio Meneghesso, Enrico Zanoni, and Matteo Meneghini "Influence of V-pits on the electro-optical properties of high-periodicity InGaN MQWs", Proc. SPIE 12886, Gallium Nitride Materials and Devices XIX, 128860C (8 March 2024); https://doi.org/10.1117/12.3004922

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