Kinetic-limited etching of magnesium doping nitrogen polar GaN in potassium hydroxide solution

• Published in: Applied surface science 2016-01, Vol.360, p.772-776
• Main Authors: Jiang, Junyan, Zhang, Yuantao, Chi, Chen, Yang, Fan, Li, Pengchong, Zhao, Degang, Zhang, Baolin, Du, Guotong
• Format: Article
• Language: English
• Subjects: Doping; Etching; Gallium nitrides; Magnesium; Mathematical models; N-polar GaN; Optimization; Oxides; Strain; Wet etching; X-rays
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.11.066

⿢Effects of Mg doping on wet etching of N-polar GaN are illustrated and analysed.⿢Etching process model of Mg-doped N-polar GaN in KOH solution is purposed.⿢It is found that Mg doping can induce tensile strain in N-polar GaN film.⿢N-polar p-GaN film with a hole concentration of 2.4ÿ1017cm⿿3 is obtained. KOH based wet etchings were performed on both undoped and Mg-doped N-polar GaN films grown by metal-organic chemical vapor deposition. It is found that the etching rate for Mg-doped N-polar GaN gets slow obviously compared with undoped N-polar GaN. X-ray photoelectron spectroscopy analysis proved that Mg oxide formed on N-polar GaN surface is insoluble in KOH solution so that kinetic-limited etching occurs as the etching process goes on. The etching process model of Mg-doped N-polar GaN in KOH solution is tentatively purposed using a simplified ideal atomic configuration. Raman spectroscopy analysis reveals that Mg doping can induce tensile strain in N-polar GaN films. Meanwhile, p-type N-polar GaN film with a hole concentration of 2.4ÿ1017cm⿿3 was obtained by optimizing bis-cyclopentadienyl magnesium flow rates.