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Applied Physics 2025
基于蓝宝石衬底的高质量AlN薄膜的制备研究
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Abstract:
在蓝宝石衬底上生长一层AlN缓冲层是LED芯片提升器件质量的常用手段，其薄膜质量与器件整体性能息息相关。为了进一步提高AlN薄膜的结晶质量，本文首先使用PVD、HTA以及MOCVD方法对蓝宝石衬底上的AlN薄膜进行制备，制备出了高结晶质量的AlN薄膜。随后引入不同的c/m衬底斜切角去探索斜切角度对薄膜结晶质量的影响。最终成功在c面蓝宝石衬底上制备出1 μm的摇摆曲线半高宽51 arcsec，表面粗糙度为0.987 nm的高质量c轴取向的AlN薄膜。并通过对比不同衬底斜切角的形貌特征变化，认为造成结晶质量提升的原因是一种由衬底斜切角诱导的台阶终止位错的机制。在此基础上，对不同衬底斜切角的AlN薄膜进行了UV光学性能的表征，通过紫外透过率实验证实了0.2？的c/m衬底斜切角确实给薄膜的性能带来了提升，其紫外透过率和光学禁带宽度都有了一定程度的提升，最终达到了80％透过率，6.09 eV光学带隙的优异性能。
A layer of AlN buffer on a sapphire substrate is a common method for improving the device quality of LED chips, and the quality of the film is closely related to the overall performance of the device. In order to further enhance the crystallinity of AlN films, this study first employs PVD, HTA, and MOCVD methods to fabricate AlN films on sapphire substrates, achieving AlN films with high crystallinity. Subsequently, different offcut angles of the c/m substrates are introduced to explore the impact of the offcut angle on the crystallinity of the films. As a result, high-quality c-axis oriented AlN films with a rocking curve full width at half maximum (FWHM) of 51 arcseconds and a surface roughness of 0.987 nm were successfully prepared on c-plane sapphire substrates. By comparing the morphological changes of films with different substrate offcut angles, it is proposed that the improvement in crystallinity is due to a mechanism where the substrate offcut angle induces the termination of step-edge dislocations. Based on this, UV optical performance of AlN films with different substrate offcut angles was characterized. Ultraviolet transmittance experiments confirmed that a 0.2？ c/m substrate offcut angle indeed enhanced the performance of the films, resulting in an improvement in both the UV transmittance and optical bandgap. Ultimately, an 80% transmittance and a 6.09 eV optical bandgap were achieved, demonstrating excellent performance.
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