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Nano-aluminum-induced crystallization Nano-aluminum-induced crystallization of amorphous siliconof amorphous silicon

指導教授：管 鴻指導教授：管 鴻學 生：郭豐榮學 生：郭豐榮學 號：學 號：M98L0213M98L0213

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OutlineOutline

• INTRODUCTION

• EXPERIMENTAL

• RESULTS AND DISCUSSION

• CONCLUSION

• REFERENCES

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INTRODUCTIONINTRODUCTION

• Increasing the average crystallite size of the poly-crystalline silicon is one very important aspect of research on AIC of a-Si:H

• Compared to traditional AIC, the nano-AIC method produces much smoother polycrystalline silicon films with significantly larger crystallites whose size increases with annealing temperature ramp-up time

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EXPERIMENTALEXPERIMENTAL

☼ PECVD

☼ a-Si:H ： 100 nm

☼ RF power ： 15 W

☼ pressure ： 0.5 Torr

☼ Ts ： 250 ℃

☼ SiH4 ： 85 sccm

☼ Thermal evaporation

☼ Al ： 30 nm

☼ Al ： 200 nm

☼ Annealing

☼ At 350 in N℃ 2

☼ Time ： 30 min

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RESULTS AND DISCUSSIONRESULTS AND DISCUSSION

Fig. 1. Microscopy and SEM images of the polycrystalline silicon film created by (a) nano-AIC of a-Si:H and (b) traditional AIC, respectively. The image inserted in (b) is a SEM photo showing details of small grains.

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RESULTS AND DISCUSSIONRESULTS AND DISCUSSION

Fig. 2. Relations between grain size and ramp up time of annealing temperature.It shows that grain size significantly increased with ramp up time for nano-AIC of a-Si:H, but changed little for traditional AIC of a-Si:H

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RESULTS AND DISCUSSIONRESULTS AND DISCUSSION

Fig. 3. Microscopy images of the grains on the samples with 20 h annealing ramp time. The largest grain size is about 90 μm, the largest size has not been reported in literature.

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RESULTS AND DISCUSSIONRESULTS AND DISCUSSION

Fig. 4. 3-D SPM images showing the surface topography of (a) a-Si:H, and polycrystalline silicon films produced by (b) nano-AIC, and (c) traditional AIC. It shows that nano-AIC created much smoother surfaces than traditional AIC.

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RESULTS AND DISCUSSIONRESULTS AND DISCUSSION

Fig. 5. XRD spectra of (a) a-Si:H, (b) nano-AIC of a-Si:H, and (c) traditionalAIC of a-Si:H. The large peaks around 2θ=28.5° are Si (111), indicatingcrystallization occurred for both (b) and (c).

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CONCLUSIONCONCLUSION

• For any given ramp-up time, the grains created by nano-AIC of a-Si:H are much larger than those produced by traditional AIC of a-Si:H

• This paper reports on the successful fabrication of continuous and smooth polycrystalline silicon films with very large grains using AIC of a-Si:H

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REFERENCESREFERENCES• Min Zou a,*, Li Cai b, Hengyu Wang a, William Brown b , a Department of

Mechanical Engineering, The University of Arkansas, Fayetteville, AR 72701, USA. b Department of Electrical Engineering, The University of Arkansas, Fayetteville, AR 72701, USA. Received 14 June 2005; accepted 10 November 2005 .Available online 9 December 2005.