The III-V nitride material such as InGaN has many favorable physical properties including a wide direct band-gap (0.7- 3.4eV), high absorption coefficients (10⁵ cm^-1), and high radiation resistance. As such, InGaN has been chosen as an excellent material for full-solar-spectrum photovoltaic applications utilizing its wide and tunable band-gap. The refractive index of GaN is about 2.5 in the full-solar-spectrum. According to the Fresnel formula, there is a high reflection of ~18.4% as the sun light entering GaN. Anti-reflection films could be used on InGaN/GaN solar cell to decrease the reflection loss. The photonic crystal structure is a kind of anti-reflection based on the effective medium theory without any limitations, for example the mismatched thermal expansion coefficient. In this paper, we reported our research work on the design and fabrication of photonic crystal structure on the surface of GaN. FDTD Solutions is used to simulate the reflectivity on the surface of GaN with hexagonal close-packed pillar which has different period-a, diameter-d and height-h. When the parameters a is 500nm, d is 300nm, the reflectivity reached the lowest point of 4.18%. The self-assembly method was used to fabricate the photonic crystal structure on the GaN surface and the fabrication process was also researched. The photonic crystal structures on the surface of p-GaN were obtained and their characteristics of the antireflective film will be discussed in detail.

Date Published: 19 February 2015
PDF: 5 pages
Proc. SPIE 9449, The International Conference on Photonics and Optical Engineering (icPOE 2014), 94491L (19 February 2015); doi: 10.1117/12.2081345

Published in SPIE Proceedings Vol. 9449:
The International Conference on Photonics and Optical Engineering (icPOE 2014)
Ailing Tian; Anand Asundi; Weiguo Liu; Chunmin Zhang, Editor(s)