| AVS 61st International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuP |
| Session: | Electronic Materials and Processing Poster Session |
| Presenter: | Satoru Kawaguchi, Meiji University, Japan |
| Authors: | S. Kawaguchi, Meiji University, Japan A. Kusunoki, Meiji University, Japan S. Yoshida, Meiji University, Japan H. Katsumata, Meiji University, Japan |
| Correspondent: | Click to Email |
Aluminum induced crystallization (AIC) is a method of crystallizing amorphous Si (a-Si) by the interaction of Al and Si during the heat treatment. Polycrystalline Si (poly-Si) can be formed at lower temperature by AIC compared to solid phase growth techniques, since AIC can crystallize amorphous Si below the eutectic temperature of Al and Si at 577 °C. Poly-Si formed by AIC usually exhibits p-type conductivity with a high carrier concentration due to existence of residual Al. On the other hand, it has been difficult to form n-type poly-Si by metal induced crystallization using n-type doping materials as Sb. The purpose of this study is to fabricate a pn junction for light-receiving device consisting of AIC p-type poly-Si and n-type Mg2Si. Mg2Si (Eg: 0.6-0.7 eV) was selected as a candidate of n-type layers because Al atoms are considered to act as an n-type dopant in Mg2Si.
The substrates used in this study were glass or p-Si (100) substrates. Al films with a thickness of 500 nm were deposited on the glass substrate by resistive evaporation. After deposition, they were exposed in the air for more than 2 hours to form native Al oxide films. Subsequently, a-Si films with a thickness of 500 nm were deposited on the Al films by radio frequency (RF) magnetron sputtering. These samples were annealed at 450-500 °C for 3-12 hours in N2 for AIC. After the AIC, Al top layer was removed with diluted HCl. Then, Mg films with a thickness of 100-300 nm were deposited either on AIC poly-Si films or p-type Si (100) substrates by resistive evaporation. These samples were annealed at 400 °C for 5 hours in Ar for solid phase growth of Mg2Si.
Optical microscope images of surface of AIC poly-Si showed that the grain size of poly-Si increased with increasing AIC temperature. All sample showed Si (111) XRD peaks at 2θ = 28 degrees and Si Raman peaks at 520 cm-1, which can be an evidence of formation of (111) preferentially oriented poly-Si by AIC. We investigated the correlation between grain size of poly-Si observed with optical microscope and FWHM of Raman peak at 520 cm-1. As a result, it was found that the AIC at higher temperature decreased grain size and increased FWHM, while the AIC for longer time increased grain size and decreased FWHM. Optical band-gap of AIC poly-Si formed at 500 °C for 12 hours was determined to be 1.1 eV from optical transmittance spectra. Hall effect measurements of AIC poly-Si showed p-type conductivity with a hole concentration of 4.0×1017 cm-3 and a hole mobility value of 1.56 cm2・V-1・s-1. Mg2Si films formed both on AIC poly-Si/glass and p-Si (100) substrates showed Raman peaks at around 256 cm-1, which originate from Mg2Si.