異質磊晶成長之氮化鎵與鑽石薄膜研究

在論文中使用TEM觀察氮化鎵晶膜中的差排，此晶膜利用MOCVD磊晶成長於(0001)面之藍寶石基板，發現GaN晶膜以藍寶石基板之共同c軸為中心相互軸旋轉錯開30o角，GaN晶膜中的差排約存在有3%(或更少)的純螺旋差排( )及20%的純刃差排( )，其它剩下的77%為混合型差排( )；MOCVD磊晶成長於藍寶石基板之GaN晶膜中主要的差排型式為混合型差排。另外，為了更進一步瞭解GaN/sapphire介面上的差排分佈形貌，我們製備了GaN/sapphire介面的平面觀察(plan-view)之TEM樣品，觀察到相當高密度的差排扭結且平躺在GaN/sapphire介面上，估算出此高應力應變介面上之差排密度約為8x109cm-2，另一截取自接近氮化鎵晶膜表面之平面觀察 TEM樣品具有6x108cm-2的差排密度，兩者相較的結果，顯示平躺在介面處的差排有7.5%轉換成穿透性差排，從介面處生長延伸至氮化鎵晶膜自由表面。我們利用氮化鎵成功異質磊晶於藍寶石基板的概念，嘗試磊晶鑽石薄膜於4英吋矽晶圓上，在這階段的研究，使用電容式耦合電漿對於大面積的鑽石薄膜成長提供了相當大的優勢，我們使用較少被使用的150MHz頻率之電漿輔助CVD方式來成長，相較於其他方式，此PECVD法不需預先的在矽晶片基板表面機械研磨或散佈鑽石晶種，於不同條件下，沈積出了奈米或微米之鑽石膜，與DLC (Diamond Like Carbon)薄膜，此150MHz的特別頻率是介於一般商用13.56MHz的RF與2.45GHz的微波之間，我們成功的利用此以一設備成長出均勻結晶之鑽石膜於4英吋之矽晶圓上，且其具有約每一小時1μm的成長速率。

關鍵字

氮化鎵；差排；鑽石；磊晶

並列摘要

In this thesis, a TEM observation of dislocations in GaN grown on (0001) sapphire by MOCVD was carried out in this study. The GaN film was rotated 30o around the c axis in the growth plane against the substrate. The finding of this research, according to TEM analysis, is that about 3% (or less) of the threading dislocations are pure-screw ( ), and 20% are pure-edge ( ). The remaining threading dislocations, about 77%, are mixed-type dislocations; i.e., the major dislocation type in GaN epitaxial layer grown on (0001) sapphire is the mixed type. In addition, for further understanding of the dislocation configuration on the interface of GaN/sapphire, a plane view TEM sample of the GaN/sapphire interface was prepared. The plane view TEM picture of GaN/sapphire interface reveals an extremely high density of kink dislocations lying on the interface, with the dislocation density, about 8x109 cm-2, involving high strain and stress. A comparison of 8x109 cm-2 dislocation density with another plane view TEM picture (6x108 cm-2) near the GaN free surface revealed approximately 7.5% of the dislocations lying on the substrate coalescing into threading dislocations generated from the interface to the GaN surface. Using the concept of hetero-epitaxial GaN grown on sapphire, we try to grow diamond films by hetero-epitaxy on 4 inch silicone wafer. Capacitive coupled plasmas offer major advantages over microwave-introduced plasmas for growth of large area thin films. In this investigation, a novel 150MHz capacitive coupled RF plasma-assisted chemical vapor deposition system was employed to generate several kinds of films, including nano or micro crystalline diamond films and DLC films, without any mechanical pretreatment (pre-seeding). A special frequency of 150MHz, between the commercial RF of 13.56MHz and microwave of 2.45GHz, was carried out to deposit a uniform and quality crystalline diamond film on 4 inch silicon wafer with a 1μm/h growth rate.

並列關鍵字

GaN ； dislocation ； diamond ； epitaxial

參考文獻

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國際替代計量

異質磊晶成長之氮化鎵與鑽石薄膜研究

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