Fabrication of Large-Grain Thick Polycrystalline Silicon Thin Films via Aluminum-Induced Crystallization for Application in Solar Cells

Hsiao-Yeh Chu,Min-Hang Weng,Chen Lin

doi:10.1155/2013/245195

Abstract

The fabrication of large-grain 1.25 μm thick polycrystalline silicon (poly-Si) films via two-stage aluminum-induced crystallization (AIC) for application in thin-film solar cells is reported. The induced 250 nm thick poly-Si film in the first stage is used as the seed layer for the crystallization of a 1 μm thick amorphous silicon (a-Si) film in the second stage. The annealing temperatures in the two stages are both 500°C. The effect of annealing time (15, 30, 60, and 120 minutes) in the second stage on the crystallization of a-Si film is investigated using X-ray diffraction (XRD), scanning electron microscopy, and Raman spectroscopy. XRD and Raman results confirm that the induced poly-Si films are induced by the proposed process.

Highlights

Silicon thin films can reduce the cost of solar cells and associated consumption of pure silicon
Polycrystalline silicon film is a promising material for solar cell application because its carrier mobility is 10 to 100 times larger than that of a hydrogenated amorphous silicon (a-Si:H) film [1]
Three methods are currently used for manufacturing polySi film on glass: catalytic chemical vapor deposition [2], excimer laser annealing (ELA) [3], and metal-induced crystallization (MIC) [4–10]

Summary

Introduction

Silicon thin films can reduce the cost of solar cells and associated consumption of pure silicon. AIC can create poly-Si film with a lateral grain size that is larger than the film thickness [5]. Commonly studied poly-Si films often have a thickness of below 500 nm [6–10], which is insufficient for the active layer of solar cells. Hossain et al [9] fabricated poly-Si films with a lateral grain size of up to 20 μm, but the film thickness was as low as 300 nm. Two-step AIC was used in the study of Tuzun et al [11]. Their process temperature was as high as 1160∘C. 1.25 μm thick large-grain poly-Si films are fabricated via a two-stage AIC method. The process temperature is 500∘C, which is below the glass transformation temperature

Experiments

Results and Discussion

Conclusion