Morphological, Structural and Optical Characteristics of Porous GaN Fabricated by UV-Assisted Electrochemical Etching

Abstract:

The fabrication of porous GaN (PGaN) by UV-assisted electrochemical etching with a variations of current densities (40, 60, and 80 mA/cm²) for 60 min in electrolytes consisting of 4% KOH are reported. Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray (EDX), Atomic Force Microscopy (AFM) and X-ray Diffraction (XRD) were used to characterize the morphological and structural characteristics of the PGaN. All PGaN sample prepared by electrochemical etching technique produced a hexagonal-like pore shape. FESEM images demonstrated that the pore uniformity and porosity are affected significantly by the current density. The PGaN sample fabricated with 80 mA/cm² produces a uniform and high porosity structure compared to other PGaN sample. This shows that the morphology and structural characteristic of PGaN are increase with the increase of current density. The EDX result revealed significant Ga and N atom presence in all samples. However, the O atom only presence in sample etched with 80 mA/cm² implying that the etching process is occur vigorously in this sample. The AFM verified that the surface roughness and the pore depth are increased as current density increased. There were relatively large variations of the peak intensities for 2Theta-scan patterns as exposed by XRD. The peak shift for PGaN sample relative to as-grown was inconsistent and the changed was relatively small. Raman intensity found to be enhanced with the increase in current density and among the PGaN sample, the E₂(high) peak for sample prepared with 60mA/cm² and 80mA/cm² was observed to be slightly shifted to lower frequency. The PL spectra displayed that the porosity has high impact on the PL peak intensity. . Overall, this proved that with the usage of low power UV light, the pore structure still can be produced as good as pore structure fabricated with high power UV light.

• Periodical: Solid State Phenomena (Volume 301)
• Pages: 3-11
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.301.3
• Online since: March 2020
• Authors: Nurul Syuhadah Mohd Razali, Alhan Farhanah Abd Rahim*, Rosfariza Radzali, Ainorkhilah Mahmood, Muhammad Faiz Bahrol Anuar
• Keywords: Current Density, Photo-Electrochemical Etching, Porous GaN, Porous Structure, Surface Morpholgy

References

[1] M. E. A. Samsudin, N. Zainal, and Z. Hassan, Controlled porosity of GaN using different pore size of Si (1 0 0) substrates,, Superlattices Microstruct., vol. 73, p.54–59, (2014).

DOI: 10.1016/j.spmi.2014.05.014

[2] F. K. Yam, Z. Hassan, and S. S. Ng, Porous GaN prepared by UV assisted electrochemical etching,, Thin Solid Films, vol. 515, no. 7–8, p.3469–3474, (2007).

DOI: 10.1016/j.tsf.2006.10.104

[3] A. Ramizy, Z. Hassan, and K. Omar, Nanostructured GaN on silicon fabricated by electrochemical and laser-induced etching,, Mater. Lett., vol. 65, no. 1, p.61–63, (2011).

DOI: 10.1016/j.matlet.2010.09.054

[4] A. Mahmood et al., Structural and optical studies of undoped porous GaN prepared by Pt-assisted electroless etching,, Mater. Sci. Forum, vol. 846, p.358–365, (2016).

DOI: 10.4028/www.scientific.net/msf.846.358

[5] A. Mahmood, Z. Hassan, Yam Fong Kwong, Chuah Lee Siang, and M. B. Md Yunus, Photoluminescence, Raman and X-ray diffraction studies of porous GaN grown on sapphire,, 2011 IEEE Colloq. Humanit. Sci. Eng. CHUSER 2011, p.677–681, (2011).

DOI: 10.1109/chuser.2011.6163819

[6] K. Al-Heuseen, M. R. Hashim, and N. K. Ali, Effect of different electrolytes on porous GaN using photo-electrochemical etching,, Appl. Surf. Sci., vol. 257, no. 14, p.6197–6201, (2011).

DOI: 10.1016/j.apsusc.2011.02.031

[7] F. K. Yam and Z. Hassan, Structural and optical characteristics of porous GaN generated by electroless chemical etching,, Mater. Lett., vol. 63, no. 8, p.724–727, (2009).

DOI: 10.1016/j.matlet.2008.12.040

[8] K. Al-Heuseen, M. R. Hashim, and N. K. Ali, Enhanced optical properties of porous GaN by using UV-assisted electrochemical etching,, Phys. B Condens. Matter, vol. 405, no. 15, p.3176–3179, (2010).

DOI: 10.1016/j.physb.2010.04.043

[9] M. R. Zhang, S. J. Qin, H. D. Peng, and G. B. Pan, Porous GaN photoelectrode fabricated by photo-assisted electrochemical etching using ionic liquid as etchant,, Mater. Lett., vol. 182, p.363–366, (2016).

DOI: 10.1016/j.matlet.2016.07.024

[10] S. F. Cheah, S. C. Lee, S. S. Ng, F. K. Yam, H. Abu Hassan, and Z. Hassan, Luminescence evolution of porous GaN thin films prepared via UV-assisted electrochemical etching,, J. Lumin., vol. 159, p.303–311, (2015).

DOI: 10.1016/j.jlumin.2014.11.028

[11] M. Ramesh and H. S. Nagaraja, Effect of current density on morphological, structural and optical properties of porous silicon,, Mater. Today Chem., vol. 3, p.10–14, (2017).

DOI: 10.1016/j.mtchem.2016.12.002

[12] R. Radzali, M. Z. Zakariah, A. Mahmood, A. F. A. Rahim, Z. Hassan, and Y. Yusof, The effect of ecthing duration on structural properties of porous Si fabricated by a new two-steps alternating current photo-assisted electrochemical etching (ACPEC) technique for MSM photodetector,, AIP Conf. Proc., vol. 1875, p.020003 (1–10), (2017).

DOI: 10.1063/1.4998357