Effect of Electrical Current Change on Aluminum Induced Crystallization of Amorphous Silicon Thin Film by Joule heating

Abstract

In this study, the effect of Joule heating using constant electrical currents was studied during aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) thin films. Samples were prepared by depositing a-Si on glass substrates by plasma enhanced chemical vapor deposition, and aluminum was then sputtered on the a-Si thin film. Constant currents of 4, 5, and 6 A were applied to the Al thin film to crystallize the a-Si thin film. Appropriate annealing times were assigned for each current value (40 s for 4 A, 20 s for 5 A, and 15.5 s for 6 A). In-situ temperature measurement during crystallization were performed with an infrared thermal camera. After crystallization, a wet etching process was conducted to remove the Al layer for clear investigation of the polycrystalline silicon (p-Si) structure. Raman spectroscopy showed a peak around 520 cm-1, which verifies the formation of p-Si thin films. Grain sizes were determined by field emission scanning electron microscopy (FESEM), which also showed that the resulting p-Si structure was porous with the average pore size of around 6 μm.