Porosification of nitride semiconductors provides a new paradigm for advanced engineering of the properties of optoelectronic materials. Electrochemical etching creates porosity in doped layers whilst leaving undoped layers undamaged, allowing the realisation of complex three-dimensional porous nanostructures, potentially offering a wide range of functionalities, such as in distributed Bragg reflectors. Porous/non-porous multilayers can be formed by etching whole, as-grown wafers uniformly in one simple process, without any additional processing steps. The etch penetrates from the top down, through the undoped layers, leaving them almost untouched. Here, atomic-resolution electron microscopy is used to show that the etchant accesses the doped layers via nanometre-scale channels that form at dislocation cores and transport the etchant and etch products to and from the doped layer respectively. Results on AlGaN and non-polar GaN multilayers indicate the same mechanism is operating, suggesting this approach may be applicable in a range of materials.
|Number of pages||14|
|Publication status||Accepted/In press - 5 Mar 2020|
- electrochemical etching
- porous nanostructures
- electron microscopy
Massabuau, F. C-P., Griffin, P. H., Springbett, H. P., Liu, Y., Kumar, R. V., Zhu, T., & Oliver, R. A. (Accepted/In press). Dislocations as channels for the fabrication of sub-surface porous GaN by electrochemical etching. APL Materials.