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Formation of large-area GaN nanostructures with controlled geometry and morphology using top-down fabrication scheme.



Dipak Paramanik, Abhishek Motayed, Geetha G. Aluri, Sergiy Krylyuk, Albert Davydov


This paper details the fabrication of GaN nanoscale structures using deep ultraviolet lithography and inductively coupled plasma (ICP) etching techniques. We were able to control the geometry (dimensions and shape) and surface morphology of such nanoscale structures by carefully selecting the etching parameters. We have compared seven different chlorine-based etch chemistries: Cl_(2), Ar, Cl_(2)/N_(2), Cl_(2)/Ar, Cl_(2)/N_(2)/Ar, Cl_(2)/H_(2)/Ar, and Cl_(2)/He/Ar. We found that nitrogen plays a significant role in fabricating high quality etched GaN nanostructures. In this paper we present the effects of variations of the etch parameters, such as gas chemistry, gas flow rate, ICP power, RF power, chamber pressure, and substrate temperature, on the etch characteristics, such as etch rate, sidewall angle, anisotropy, mask erosion, and surface roughness. Dominant etch mechanisms in relation to the observed characteristics of the etched features are discussed. Utilizing such methods, we demonstrated the fabrication of nanoscale structures with designed shapes and dimensions over large area. Nanocolumns with diameter of 120 nm and height of 1.6 m with sidewall angle of 86° (90° represent a vertical sidewall) were fabricated. Nanocones with tip diameter of 30 nm and height of 1.6 um with sidewall angle of 70° were demonstrated. Such structures could potentially be used in light-emitting diodes, laser diodes, photodetectors, vertical transistors, field-emitters, and photovoltaic devices. This study indicates the feasibility of top-down methods in fabrication of next-generation of nitride-based nanoscale devices, with large area uniformity and scalability.
Journal of Vacuum Science and Technology B


Paramanik, D. , Motayed, A. , Aluri, G. , Krylyuk, S. and Davydov, A. (2012), Formation of large-area GaN nanostructures with controlled geometry and morphology using top-down fabrication scheme., Journal of Vacuum Science and Technology B (Accessed July 15, 2024)


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Created June 25, 2012, Updated October 12, 2021