PEALD-deposited crystalline GaN films on Si(100) substrates with sharp interfaces

Polycrystalline gallium nitride(GaN) thin films were deposited on Si(100) substrates via plasma-enhanced atomic layer deposition(PEALD) under optimal deposition parameters. In this work, we focus on the research of the GaN/Si(100)interfacial properties. The x-ray reflectivity measurements show the clearly-resolved fringes for all the as-grown GaN films, which reveals a perfectly smooth interface between the GaN film and Si(100), and this feature of sharp interface is further confirmed by high resolution transmission electron microscopy(HRTEM). However, an amorphous interfacial layer(~ 2 nm) can be observed from the HRTEM images, and is determined to be mixture of Ga_xO_y and GaN by xray photoelectron spectroscopy. To investigate the effect of this interlayer on the GaN growth, an AlN buffer layer was employed for GaN deposition. No interlayer is observed between GaN and AlN, and GaN shows better crystallization and lower oxygen impurity during the initial growth stage than the GaN with an interlayer.

碳化硅器件封装进展综述及展望

碳化硅(SiC)具有禁带宽、临界击穿场强大、热导率高、高压、高温、高频等优点。应用于硅基器件的传统封装方式寄生电感参数较大,难以匹配SiC器件的快速开关特性,同时在高温工况下封装可靠性大幅降低,为充分发挥SiC器件的优势需要改进现有的封装技术。针对上述挑战,对国内外现有的低寄生电感封装方式进行了总结。分析了现有的高温封装技术,结合新能源电力系统的发展趋势,对SiC器件封装技术进行归纳和展望。

柔性衬底上使用等离子增强原子层沉积制备的氮化镓薄膜物性分析

采用等离子增强原子层沉积技术(PE-ALD)在350℃温度下,在KAPTON柔性衬底上直接生长出多晶GaN薄膜。利用低角度掠入射X射线衍射仪、AFM、SEM、TEM、XPS对薄膜的晶体结构、表面形貌及薄膜成分进行了表征和分析。结果表明,薄膜呈多晶态,且具有良好的均匀性;薄膜中的N元素全部以N-Ga键形式存在;大部分Ga元素以Ga-N键形式构成GaN;少量的Ga元素分别以Ga-Ga键和Ga-O键形式构成金属镓以及Ga2O_3。研究发现,虽然KAPTON具有较好的耐高温性,但GaN会反向扩散进入KAPTON衬底,形成具有一定厚度的GaN扩散层。