1 Nano-aluminum-induced crystallization of amorphous silicon 指導教授：管 鴻 學 生：郭豐榮 學 號： M98L0213

2 Outline INTRODUCTION EXPERIMENTAL RESULTS AND DISCUSSION CONCLUSION REFERENCES

3 INTRODUCTION 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

4 EXPERIMENTAL ☼ PECVD ☼ a-Si:H ： 100 nm ☼ RF power ： 15 W ☼ pressure ： 0.5 Torr ☼ Ts ： 250 ℃ ☼ SiH 4 ： 85 sccm ☼ Thermal evaporation ☼ Al ： 30 nm ☼ Al ： 200 nm ☼ Annealing ☼ At 350 ℃ in N 2 ☼ Time ： 30 min

5 RESULTS 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.

6 RESULTS 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

7 RESULTS 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.

8 RESULTS AND DISCUSSION Fig 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.

9 RESULTS AND DISCUSSION Fig. 5. XRD spectra of (a) a-Si:H, (b) nano-AIC of a-Si:H, and (c) traditional AIC of a-Si:H. The large peaks around 2θ=28.5° are Si (111), indicating crystallization occurred for both (b) and (c).

10 CONCLUSION 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

11 REFERENCES 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.