Improved surface morphology of flow-modulated MOVPE grown AIN on sapphire using thin medium-temperature AIN buffer layer
Improved surface morphology of flow-modulated MOVPE grown AIN on sapphire using thin medium-temperature AIN buffer layer
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DOI：
10.1016/j.apsusc.2007.05.082
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发表时间：
2007-10
影响因子：
6.7
通讯作者：
Dabing Li;Masakazu Aoki;H. Miyake;K. Hiramatsu
中科院分区：
文献类型：
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作者：
Dabing Li;Masakazu Aoki;H. Miyake;K. Hiramatsu
采用低压流动调制（FM）金属有机物气相外延（MOVPE）技术，在（0001）蓝宝石衬底上生长了高温（HT）AlN薄膜，并对其生长机理进行了研究。为抑制三甲基铝（TMA）源与氨（NH3）源间的寄生反应，采用交替进料方式将TMA和NH3引入MOVPE反应器。通过扫描电子显微镜（SEM）、原子力显微镜（AFM）和X射线摇摆曲线（XRC）测量（0002）和（10-12）衍射表征表面形貌和结晶质量。原子力显微镜和扫描电子显微镜的测量表明，薄MT-AIN层的HT-AIN薄膜的表面形貌有很大的影响。通过插入薄MT-AlN缓冲层，表面形貌变得相当光滑，并且对于插入和不插入薄MT-AlN缓冲层的HT-AlN膜，表面RMS粗糙度值分别为0.84nm和13.4nm。通过在KOH水溶液中对样品进行蚀刻，发现AlN膜的极性不同，具有薄MT-AlN层的HT-AlN膜不能被蚀刻，表明该膜具有Al极性表面;而没有MT-AlN层的膜被蚀刻，这解释了该膜具有N极性或混合极性表面。提出并详细讨论了有无MT-AlN薄层时HT-AlN不同极性的起源机制。
High-temperature (HT) AIN films were grown on (0001) sapphire by low-pressure flow-modulated (FM) metal organic vapor phase epitaxy (MOVPE) with and without inserting a thin medium-temperature (MT) AIN layer. To suppress parasitic reactions between the sources of trimethylaluminum (TMA) and ammonia (NH3), TMA and NH3was introduced to the reactor of MOVPE by alternating supply way. Surface morphology and crystalline quality were characterized by a scanning electronic microscopy (SEM), atomic force microscopy (AFM) and X-ray rocking curve (XRC) measurements of (0002) and (10–12) diffractions. The AFM and SEM measurements indicated that the thin MT-AIN layer had a strong influence on the surface morphology of the HT-AIN films. The surface morphology became quite smooth by inserting the thin MT-AIN layer and surface RMS roughness values were 0.84nm and 13.4nm for the HT-AIN films with and without inserting the thin MT-AIN buffer layer, respectively. By etching the samples in aqueous KOH solution, it was found that the polarity of AIN films was different, the HT-AIN film with the thin MT-AIN layer could not be etched, indicating that the film had an Al-polar surface; however, the film without the MT-AIN layer was etched, which was explained that that film had a N- or mixed-polar surface. The mechanism for the origin of the different polarity of HT-AIN with and without the thin MT-AIN layer was proposed and discussed in detail.