Enhanced Strain Relaxation in AlGaN Layers Grown on Sputter‐Based AlN Templates. Issue 4 (23rd January 2020)

• Record Type: Journal Article
• Authors: Mogami, Yosuke; Osawa, Atsushi; Ozaki, Kazuto; Tanioka, Yukitake; Maeoka, Atsushi; Itokazu, Yuri; Kuwaba, Shunsuke; Jo, Masafumi; Maeda, Noritoshi; Yaguchi, Hiroyuki; Hirayama, Hideki
• Other Names: Shadi Shahedipour-Sandvik F. guestEditor.; Qhalid Fareed guestEditor.
• Is Part Of: Physica status solidi. Volume 257:Issue 4(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-01-23
• Subjects: AlGaN -- AlN templates -- annealing -- sputtering -- strain relaxation -- strain states; Solid state physics -- Periodicals; Solids -- Periodicals; Atomic structure -- Periodicals; 530.41
• DOI: 10.1002/pssb.201900590
• Languages: English
• ISSNs: 0370-1972

Abstract

Abstract : Strain plays a crucial role in the performance of ultraviolet (UV) optoelectronic devices. The strain states of AlGaN layers grown on different AlN templates are investigated. Two types of AlN templates are prepared: one is grown solely by metal‐organic chemical vapor deposition (MOCVD), and the other is fabricated with the combination of direct current (DC) sputtering, high‐temperature annealing, and MOCVD growth. The qualities of 4 μm‐thick MOCVD AlN and 1.2 μm‐thick sputter‐based AlN are almost equivalent in terms of dislocation density and surface morphology. However, the strain relaxation ratio of the AlGaN layer is higher for the 1.2 μm sputter‐based AlN than the 4 μm MOCVD AlN, indicating that the strain state depends on the total thickness of the epilayers on the sapphire substrate. In addition, it is found that the curvature of the sample at room temperature is governed mainly by the thickness of the AlGaN layer. As a result, sputter‐based AlN templates allow for the enhanced strain relaxation of the AlGaN layer with a small sample bowing. Abstract : The strain states of the AlGaN layer grown on AlN templates with different thicknesses are investigated. The qualities of 4 μm‐thick metal‐organic chemical vapor deposition (MOCVD) AlN and 1.2 μm‐thick sputter‐based AlN are almost equivalent in terms of dislocation density and surface morphology. However, thinner AlN templates allow for the enhanced strain relaxation of the AlGaN layer with a small sample bowing.