低溫製備薄型矽基鍺磊晶薄膜:硼重摻雜層與本質層之研究;Low Temperature Growth of Silicon-based Epitaxial Heavy Boron-doped Germanium Films and Silicon-based Epitaxial Intrinsic Germanium Films.

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71966

Title:	低溫製備薄型矽基鍺磊晶薄膜:硼重摻雜層與本質層之研究;Low Temperature Growth of Silicon-based Epitaxial Heavy Boron-doped Germanium Films and Silicon-based Epitaxial Intrinsic Germanium Films.
Authors:	李銘捷;Li,Ming-jie
Contributors:	照明與顯示科技研究所
Keywords:	電子迴旋共振沉積法;矽基鍺薄膜;硼摻雜層鍺薄膜;本質層鍺薄膜;鍺薄膜;ECR-CVD;silicon-based germanium thin films;boron-doped germanium thin films;intrinsic germanium thin films;germanium thin films
Date:	2016-07-22
Issue Date:	2016-10-13 14:09:25 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究利用電子迴旋共振化學氣相沉積法低溫(210°C)成長薄型硼重摻雜鍺磊晶薄膜與本質層鍺磊晶薄膜。硼重摻雜鍺薄膜可利用在矽基鍺光偵測器上，其中硼摻雜可以改善薄膜電性、增進元件效能，但會降低結晶品質，由調變電子迴旋共振化學氣相沉積系統成長參數並對薄膜做後退火處理，以改善結晶情形。本質層鍺磊晶薄膜可應用於矽基砷化鎵太陽能電池中，作為砷化鎵薄膜和矽基板的緩衝層，而鍺的厚度會影響底部電池的光吸收，我們將成長薄型之鍺緩衝層，再調變退火參數，得到結晶品質最佳之薄膜。藉由調變電子迴旋共振化學氣相沉積系統之製程參數，低溫成長薄型硼重摻雜鍺磊晶薄膜。X光繞射結果顯示，薄型重摻雜鍺薄膜為(311)單晶。而鍺薄膜之半高寬隨氫氣流量增加而提高，原因在於過多氫氣對鍺表面進行蝕刻，造成薄膜品質下降。此外我們使用穿透式電子顯微鏡與原子力顯微鏡分析薄膜表面與結構，得知薄膜厚度為30 nm，而方均根值為0.67 nm。此結果顯示，薄膜表面粗糙度為元件等級的水準。另一方面，電性對元件性質影響很大，因此本實驗藉由重摻雜來提高薄膜之電性。而霍爾量測系統顯示磊晶鍺薄膜之最佳電阻率、載子濃度和載子遷移率分別為5.9×10-4 Ω-m、6.03×1020 cm-3、17.6 cm2/V-s。本研究成長出120nm之本質層鍺薄膜，再以不同的參數做退火處理，經XRD和SIMS量測，發現除了單一溫度退火(700°C、持續5分鐘)後之薄膜，其他退火參數都會造成薄膜和基板互相擴散，使XRD半高寬下降。我們最後獲得退火後薄膜之XRD半高寬為288 arcsec。將120nm之本質層鍺薄膜分別沉積0°與偏6°矽基板上，再分別於鍺薄膜上成長ㄧ層砷化鎵薄膜。由XRD量測得到，0°與偏6°矽基板之砷化鎵薄膜，其XRD半高寬分別為291 arcsec和454 arcsec。主因於偏6°基板上的砷化鎵薄膜，原子結晶會較差。 ;In this study, the silicon-based epitaxial heavy boron-doped germanium films and silicon-based epitaxial intrinsic germanium films is grown by electron cyclotron resonance chemical vapor deposition. Heavy boron-doped germanium epilayer is available for the application in silicon-based germanium photodetectors. In this study, we grow the heavy boron-doped germanium epilayer at vary growth parameter using electron cyclotron resonance chemical vapor deposition system at low growth temperature of 180°c, then the films is annealed, which improve the crystallization. The XRD patterns of the boron doped Ge epilayers that exhibits the crystalline phase at 53.7 degree corresponding to the (311)crystal orientations, while the XRD FWHM of the films is increased when the H2 flow rate is decresed, due to the etching effect on the Ge surface by excess hydrogen atoms. Besides, we use TEM and AFM to analysis the surface and the structure of the films. Then, we found that the thickness is 30nm and the RMS roughness is 0.67nm. These shows the quality of the films is suit to apply in device. The electrical properties of boron-doped Ge epilayers on Si substrates are characterized by Hall measurements. the resistivity of the best quality of boron doped Ge epilayers is 5.9×10-4 Ω-m, the carrier concentration is 6.03×1020 cm-3 and the carrier mobility is 17.6 cm2/V-s. Intrinsic epitaxial germanium films is available for the application in silicon-based GaAs solar cells, as the buffer layer between the GaAs layer and the silicon substrate. In this study, we grow intrinsic germanium films by ECR-CVD system and anneal it at different processes in order to improve the crystallization of the films. XRD and SIMS results show that only the process of annealing at 700°c for 300s will obtain the best XRD FWHM(288arcsec) of Ge epilayers, due to over annealing time lead the silicon and germanium interdiffusion. On the other hand, we grow the intrinsic germanium films on a no offcut and a 6°offcut silicon substrate as the virtual substrates. Then, we grow GaAs films on the two virtual substrates. By XRD analysis, the XRD FWHM of the no offcut and a 6°offcut GaAs films is 291 arcsec and 454 arcsec, repectively.
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