Influence of the reactor environment on the selective area thermal etching of GaN nanohole arrays

Pierre Marie Coulon, Peng Feng, Benjamin Damilano, Stéphane Vézian, Tao Wang, Philip A. Shields

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Abstract

Selective area thermal etching (SATE) of gallium nitride is a simple subtractive process for creating novel device architectures and improving the structural and optical quality of III-nitride-based devices. In contrast to plasma etching, it allows, for example, the creation of enclosed features with extremely high aspect ratios without introducing ion-related etch damage. We report how SATE can create uniform and organized GaN nanohole arrays from c-plane and (11-22) semi-polar GaN in a conventional MOVPE reactor. The morphology, etching anisotropy and etch depth of the nanoholes were investigated by scanning electron microscopy for a broad range of etching parameters, including the temperature, the pressure, the NH3 flow rate and the carrier gas mixture. The supply of NH3 during SATE plays a crucial role in obtaining a highly anisotropic thermal etching process with the formation of hexagonal non-polar-faceted nanoholes. Changing other parameters affects the formation, or not, of non-polar sidewalls, the uniformity of the nanohole diameter, and the etch rate, which reaches 6 µm per hour. Finally, the paper discusses the SATE mechanism within a MOVPE environment, which can be applied to other mask configurations, such as dots, rings or lines, along with other crystallographic orientations.

Original languageEnglish
Article number5642
JournalScientific Reports
Volume10
Issue number1
DOIs
Publication statusPublished - 27 Mar 2020

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