Optimization of the p-GaN window layer for InGaN/GaN solar cells

• Published in: 2010 35th IEEE Photovoltaic Specialists Conference pp. 002089 - 002092
• Main Authors: Neufeld, C J, Chen, Z, Cruz, S C, Toledo, N G, DenBaars, S P, Mishra, U K
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.06.2010
• ISBN: 9781424458905; 1424458900
• ISSN: 0160-8371
• DOI: 10.1109/PVSC.2010.5616061

In this work we report on the optimization of the p-GaN window layer for InGaN/GaN solar cells. We studied the effect of p-GaN thickness and growth temperature on the electrical performance. By optimizing the window thickness of In x Ga 1-x N solar cells with X In ≈ 0.04 we maximized short wavelength response and produced solar cells with 82% FF and Voc of 2 V and enhancement of Jsc of 80% over un-optimized devices. We also studied the effect of growth temperature of the window layer, and found that the electrical performance was greatly improved with higher growth temperatures. By increasing the p-GaN growth temperature from 890°C to 1040°C, reverse bias leakage was reduced by three orders of magnitude, Voc increased from 0.85 to 1.65 V and peak output power increased by nearly 100% for devices with X In ≈ 0.08. Surface pit density was also significantly decreased by increasing growth temperature and seems to be an important mechanism for leakage in these devices.