Tensile strain‐induced formation of micro‐cracks for AlGaN/GaN heterostructures. Issue 5 (6th February 2013)

• Record Type: Journal Article
• Authors: Kotani, Junji; Tomabechi, Shuichi; Miyajima, Toyoo; Nakamura, Norikazu; Kikkawa, Toshihide; Watanabe, Keiji; Imanishi, Kenji; Krishna, Sanjay; Plis, Elena
• Is Part Of: Physica status solidi. Volume 10:Issue 5(2013:May)
• Page Start: 808
• Page End: 811
• Publication Date: 2013-02-06
• Subjects: Solid state physics -- Congresses; Solid state physics -- Periodicals; Solid state physics; Conference proceedings; Periodicals; 530.41
• DOI: 10.1002/pssc.201200627
• Languages: English
• ISSNs: 1862-6351

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>This paper investigated the effect of tensile strain in AlGaN barrier layer on the formation of micro‐cracks at the surface of AlGaN/GaN HEMT structures. The Al_0.2Ga_0.8N/GaN HEMT structures were cooled down under N₂ + NH₃ and H₂ + NH₃ environments and high‐density micro‐cracks were found only for the latter case, indicating that hydrogen etching is essential for crack formation. On the other hand, no micro‐cracks were observed even for H₂ + NH₃ cooling for thick AlGaN bulk layer. These results clearly correlate the tensile strain in the epitaxial layer and the formation of micro‐cracks. Cross‐sectional TEM analysis unveiled that screw/mixed dislocations were responsible for the formation of micro‐cracks. It is believed that etching preferably starts from the dislocations and propagates along the crystal planes with the help of the tensile strain in the epitaxial layers. (© 2013 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)</p> </abstract>