Epitaxial growth of nonpolar GaN films on r-plane sapphire substrates by pulsed laser deposition

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• 作者：Weijia Yang^a ; Wenliang Wang^a ; Haiyan Wang^a ; Yunnong Zhu^a ; Guoqiang Li^a ; ^b ; ^c ; ^{msgli@scut.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Nonpolar GaN films ; r-plane sapphire ; Pulsed laser deposition ; Interfacial layer
• 刊名：Materials Science in Semiconductor Processing
• 出版年：2016
• 出版时间：1 March 2016
• 年：2016
• 卷：43
• 期：Complete
• 页码：82-89
• 全文大小：1745 K

文摘

Single-crystalline nonpolar GaN epitaxial films have been successfully grown on r-plane sapphire (Al₂O₃) substrates by pulsed laser deposition (PLD) with an in-plane epitaxial relationship of GaN[1-100]//Al₂O₃[11-20]. The properties of the ~500 nm-thick nonpolar GaN epitaxial films grown at temperatures ranging from 450 to 880 °C are studied in detail. It is revealed that the surface morphology, the crystalline quality, and the interfacial property of as-grown ~500 nm-thick nonpolar GaN epitaxial films are firstly improved and then decreased with the growth temperature changing from 450 to 880 °C. It shows an optimized result at the growth temperature of 850 °C, and the ~500 nm-thick nonpolar GaN epitaxial films grown at 850 °C show very smooth surface with a root-mean-square surface roughness of 5.5 nm and the best crystalline quality with the full-width at half-maximum values of X-ray rocking curves for GaN(11-20) and GaN(10-11) of 0.8° and 0.9°, respectively. Additionally, there is a 1.7 nm-thick interfacial layer existing between GaN epitaxial films and r-plane sapphire substrates. This work offers an effective approach for achieving single-crystalline nonpolar GaN epitaxial films for the fabrication of nonpolar GaN-based devices.