Homoepitaxial GaN micropillar array by plasma-free photo-enhanced metal-assisted chemical etching

Metal-assisted chemical etching is a plasma-free open-circuit anisotropic etching method that produces high aspect ratio structures in various semiconductors. Here, for the first time, we demonstrate the formation of ordered micropillar arrays of homoepitaxial GaN, using photo-enhanced MacEtch with patterned platinum films as the catalyst. The GaN etching rate and morphology as a function of etching chemistry, growth method, and doping conditions are investigated, and the etch mechanism is analyzed. Etch rates and surface smoothness are found to increase with the Si-doping level in GaN, approaching those achieved by reactive ion etching and photoelectrochemical etching. Spatially resolved photoluminescence shows no degradation in near band edge emission and no newly generated defect peaks, as expected due to the high energy ion free nature. This approach can also potentially be applied to InGaN and AlGaN by tuning the etch chemistry and illumination wavelength, enabling a facile and scalable processing of 3D III-nitride based electronic and optoelectronic devices such as mu LEDs and finFETs.

Automated summary

Metal-assisted chemical etching is a plasma-free method that can produce high aspect ratio structures, with potential applications in electronic and optoelectronic devices. The method was successfully demonstrated with ordered micropillar arrays of homoepitaxial GaN, showing promising results in spatially resolved photoluminescence. This approach may also be extended to InGaN and AlGaN, offering a facile and scalable processing route for III-nitride based devices.