In-situ decomposition and etching of AlN and GaN in the presence of HCl

• Published in: Journal of crystal growth Vol. 393; pp. 89 - 92
• Main Authors: Fahle, Dirk, Kruecken, Thomas, Dauelsberg, Martin, Kalisch, Holger, Heuken, Michael, Vescan, Andrei
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2014; Elsevier
• Subjects: A1. Etching; A3. Hot wall epitaxy; A3. Metalorganic vapor phase epitaxy; Aluminum nitride; B1. Nitrides; Constraining; Cross-disciplinary physics: materials science; rheology; Decomposition; Etching; Exact sciences and technology; Gallium nitrides; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Partial pressure; Physics; Reactors; Vapor phase epitaxy; growth from vapor phase; A1. Etching; A3. Metalorganic vapor phase epitaxy; B1. Nitrides; A3. Hot wall epitaxy; Temperature dependence; Gallium; Aluminium nitride; Etching rate; VPE; Etching; Gallium nitride; III-V compound; Partial pressure; MOVPE method; Activation energy; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2013.09.025

The etch rates of gaseous HCl on AlN and GaN in H2 ambient in a MOVPE reactor have been studied. For AlN, etching by HCl in H2 and N2 is compared. When etching GaN in hydrogen by HCl, a dependency of etch rate on temperature was found and the activation energy was determined. We propose a two-step reaction in which the first step, the decomposition of GaN, is the limiting one. The second step consists of a reaction of Ga with HCl to form volatile GaCl. We noticed that the decomposition step is enhanced with increased hydrogen partial pressure. Further, we observed that a coverage of the surface with Ga enhances the decomposition rate. By using a pulsed supply of HCl into the reactor a Ga-rich surface was maintained and the etch rate enhanced up to a temperature of 830°C. •Systematic study on etch rates of gaseous HCl on AlN and GaN in a MOVPE reactor•For etching GaN in H2 by HCl the activation energy determined.•A coverage of the GaN surface with Ga enhances the etch rate.•A pulsed supply of HCl enhances the etch rate up to a temperature of 830°C.