Role of p-GaN layer thickness in the degradation of InGaN-GaN MQW solar cells under 405 nm laser excitation

Journal Article · 25 September 2022 · Microelectronics and Reliability

DOI: https://doi.org/10.1016/j.microrel.2022.114727 · OSTI ID:2421830

Nicoletto, Marco ^[1]; Caria, Alessandro ^[2]; De Santi, Carlo ^[2]; Buffolo, Matteo ^[2]; Huang, Xuanqi ^[3]; Fu, Houqiang ^[4]; Chen, Hong ^[3]; Zhao, Yuji ^[5]; Meneghesso, Gaudenzio ^[2]; Zanoni, Enrico ^[2]; Meneghini, Matteo ^[2]

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1. University of Padova (Italy); OSTI
2. University of Padova (Italy)
3. Arizona State Univ., Tempe, AZ (United States)
4. Iowa State Univ., Ames, IA (United States)
5. Arizona State Univ., Tempe, AZ (United States); Rice Univ., Houston, TX (United States)

GaN-based solar cells with InGaN multiple quantum wells (MQWs) are promising devices for application in space environment, concentrator solar systems, wireless power transmission and multi-junction solar cells. It is therefore important to understand their degradation kinetics when submitted to high-temperature and high-intensity stress. We submitted three samples of GaN-InGaN MQW solar cells with p-AlGaN electron-blocking-layer with different thickness of the p-GaN layer to constant power stress at 310 W/cm², 175 °C for several hundred hours. The main degradation modes are a reduction of open-circuit voltage, short-circuit current, external quantum efficiency, power conversion efficiency and electroluminescence. In particular, we observed that a thinner p-GaN layer results in a stronger degradation observed on the cell operating parameters. The analysis of the dark I-V characteristics showed an increase in low-forward bias current and the analysis of electroluminescence showed a decrease in the electroluminescene emitted by the (forward biased) cell, as a consequence of stress. This work highlights that the cause of degradation is possibly related to a diffusion mechanism, which results in an increase of defect density in the active region. Finally, the impurities involved in the diffusion processes possibly originate from the p-side of the devices, therefore a thicker p-GaN layer reduces the amount of defects reaching the active region.

• Research Organization: Arizona State Univ., Tempe, AZ (United States); Energy Frontier Research Centers (EFRC) (United States). Ultra Materials for a Resilient, Smart Electricity Grid (ULTRA)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0021230
• OSTI ID: 2421830
• Journal Information: Microelectronics and Reliability, Journal Name: Microelectronics and Reliability Vol. 138; ISSN 0026-2714
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English