

- Warsaw-4-PhD School
- Doctoral studies
Electrochemical etching of GaN:Mg published in Acta Materialia Congratulations for Natalia Fiuczek and the NL 14 Team!

Electrochemical etching (ECE) of n-type GaN has been studied already for about a decade. Good understanding and reproducibility of the process made this technique an interesting route to tune the refractive index of GaN by changing its porosity. However, for p-type GaN, there seemed to be an obstacle for the application of the controllable ECE process. Our collegues address this issue in their recent paper ‘’Electrochemical etching of p-type GaN using a tunnel junction for efficient hole injection” just published by N. Fiuczek et al. in a prestigious journal Acta Materialia.
In this work electrochemical etching without use of a supra-bandgap light under constant bias of p-type GaN was reported for the first time. Thanks to the tunnel junction used as an injection layer, homogeneous and controllable etching of GaN:Mg and InGaN:Mg layers was obtained. Interestingly, the bias range for which porous layers were obtained was very narrow, ~0.4 V. The threshold etching bias (2.2V) and the bias for which strong etching was obtained (2.4V) were much lower than for the GaN:Si layers with a corresponding n-type concentration. It was demonstrated that the hole transport did not limit etching up to 200 µm lateral distance. The proposed theoretical model explains the band structure of the etched samples and the etching mechanism.