The Effects of an Oxide Layer on the Kinetics of Metal-Induced Crystallization of a-Si:H

Abstract

The effect of a native silicon dioxide layer on metal-induced crystallization of hydrogenated amorphous silicon ͑a-Si:H͒ was investigated. Several samples, deposited by the plasma-enhanced chemical vapor deposition technique, were exposed to different ambients for different times to allow for the growth of SiO 2 layers of different thicknesses. Then, aluminum was used to crystallize the samples using metal-induced crystallization at temperatures far below the solid-phase crystallization temperature of a-Si. In this study, we focused on the effects of the native oxide layer on crystallization and crystallization rates of the samples, as determined by X-ray diffraction. Following crystallization, scanning electron microscopy, environmental scanning electron microscopy, energy dispersive spectroscopy, and atomic force microscopy were used to examine and compare the morphology and chemical composition of the surface of the different samples. Finally, an explanation of the findings is presented.

Aluminum–silicon interdiffusion in silicon heterojunction solar cells with a-Si:H(i)/a-Si:H(n/p)/Al rear contacts

“…Although a-Si:H(i)/a-Si:H(n)/Al and a-Si:H(i)/a-Si:H(p)/ Al contacts have different stability challenges with increasing annealing temperature, each type could benefit by buffering the onset of Al diffusion at its interface with the doped a-Si:H. This could be done by tuning the oxidation of the a-Si:H stack before Al deposition. This is a known approach to slow the interdiffusion process by increasing the Al-Si distance, but must be implemented in a way that does not become prohibitively resistive [42]. Another approach is to incorporate Si into the Al sputter target, which may reduce the driving force for Al diffusion into the a-Si:H layers and the strength of the Si-Si and Si-H bond screening compared to pure Al [43].…”

Crystallization of patterned amorphous si and ge thin films for 3D integrated optoelectronics

“…Metal induced crystallization (MIC) has been reported to obtain crystalline films of Si and Ge from amorphous Si (a-Si) and amorphous Ge (a-Ge) at low temperatures (150-200°C) [3]. In this process, large grains of poly-Si and poly-Ge with sizes of a few millimeters can be obtained.…”

Selected area crystallization of amorphous Si and Ge thin films on glass substrates for solar cell and 3D-optoelectronic applications

“…The grain sizes of the processed films are in the order of few microns. Metal induced crystallization (MIC), on the other hand, has been reported to obtain large grains (~ 150 micros) polycrystalline films of Si and Ge at low temperatures (150-200°C) [3] at much lower cost. The results indicated that the interface layer comprising of the semiconductor oxide between metal and the amorphous film plays an important role in the crystallization process.…”