Stress control in GaN/sapphire templates for the fabrication of crack-free thick layers

详细信息    查看全文

• 作者：J. Napierala ; D. Martin ; N. Grandjean and M. Ilegems
• 关键词：A1. Defects ; A1. Stresses ; A3. Hydride vapor phase epitaxy ; A3. Metalorganic vapor phase epitaxy ; B2. Semiconducting III– ; V materials
• 刊名：Journal of Crystal Growth
• 出版年：2006
• 出版时间：1 April 2006
• 年：2006
• 卷：289
• 期：2
• 页码：445-449
• 全文大小：205 K

文摘

The reduction of the tensile stress contained in GaN layers grown on sapphire by metalorganic vapor phase epitaxy (MOVPE) is achieved using a low density of initial GaN crystallites. The template layers exhibit a significant reduction in dislocation density, down to 5×10⁷ cm⁻² in 6 μm thick MOVPE GaN templates. The grain size and their density are controlled during the low temperature nucleation step of GaN on sapphire. Subsequently, very thick (up to 200 μm) crack-free GaN layers were successfully grown by hydride vapor phase epitaxy (HVPE). A direct correlation between the stress state of the GaN/sapphire template prepared by MOVPE and the critical thickness for crack appearance during HVPE growth thickening is presented.