雙加熱器有機金屬化學氣相沉積系統上、下加熱板溫度對氮化銦鎵薄膜成長之研究

Abstract

本論文中我們探討雙加熱器有機金屬化學氣相沉積系統上加熱板及成長溫度對氮化銦鎵(InGaN)薄膜的成長差異。利用X光繞射及光激螢光系統探討其材料及光學特性。 在提升上加熱板溫度系列中，InGaN薄膜銦組成從0.5降至0.15，X光峰值繞射半寬從1300 arcsec降至約600arcsec。此外亦透過SEM俯視圖我們觀察到表面並無銦液滴形成。在成長效率分析上，比對上加熱板系列與下加熱板系列的結果，顯示出上加熱板溫度提高對成長表面溫度影響較大，主要是來自上加熱板的熱輻射效應，提高表面等效溫度，使銦組成鎔入率降低。光學特性方面，提高上加熱板溫度可提升紅光波段InGaN薄膜光學品質，在光強度上可比擬藍綠光波段，且半高寬達200meV。我們認為適度調整上加熱板溫度可改善活性氮供應不足，降低缺陷形成及組成不均勻。

In this thesis, we study the ceiling and substrate temperatures on growth of InGaN films using the two-heater MOCVD reactor. The structural and optical properties were investigated by X-ray diffraction and Photo- luminescence(PL) measurements. In the series of samples growing at different ceiling temperatures, the indium content in InGaN films decrease as raising ceiling temperatures, and the full-width of half maximum of the Łc-2Łc curves decrease from 1300 arc-sec to about 600 arc-sec. In addition, the top-view scanning electron microscope image show no evidence of indium droplets on the growth surface. Growth efficiency analysis indicate that the effective surface temperature maybe increasing by thermal radiation of the ceiling heater, reducing the In incorporation in epilayer. The integrated PL intensity shows significant increasing at Red emission region. This suggest that the formation of defect due to insufficient of active nitrogen at low growth temperature could be improved by raising ceiling temperature to an optimized value.