Structural, Eelectronic and Optical Properties of Ultra-thin Hydrogenated Amorphous Germanium Films
| Autor: | 林涛 Lin Tao, 徐骏 Xu Jun, 陈坤基 Chen Kun-ji, 李悰 Li Cong, 李淑鑫 Li Shu-xin, 李伟 Li Wei |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Radiation
Photoluminescence Materials science Band gap business.industry Condensed Matter Physics Electronic Optical and Magnetic Materials Amorphous solid symbols.namesake Plasma-enhanced chemical vapor deposition Ellipsometry symbols Optoelectronics Light emission Raman spectroscopy business Luminescence |
| Zdroj: | Chinese Journal of Luminescence. 32:1165-1170 |
| ISSN: | 1000-7032 |
| DOI: | 10.3788/fgxb20113211.1165 |
| Popis: | Ultra-thin hydrogenated amorphous germanium films,with various thickness from 160 nm to 5 nm were grown by plasma enhanced chemical vapor deposition technique.The film structure was characterized by Raman spectroscopy,which exhibited a broad band centered around 280 cm-1 indicating their amorphous nature.The film thickness and optical properties were evaluated by ellipsometer spectroscopy.The measured thickness was well consistent with the pre-designed value and the optical band gap was about 1 eV which slightly increased with the decrease of film thickness.The temperature dependent conductivity of the films was measured.The electronic transport was believed to occur in the extended-states and the corresponding activation energy is about 0.3~0.4 eV.The light emission in infrared region from the films can be detected at low temperature.The sample for 160 nm had a broad luminescence band which can be divided into two sub-bands centered at 0.78 eV and 0.67 eV,respectively.By decreasing the films thickness less than 10 nm,the luminescence band beaome narrower and only a band at 0.8 eV was observed.It may be due to the relatively more hydrogen in the ultrathin films,which passivated the defect states and suppressed the defect-related luminescence.The non-radiative activation energy increased in ultrathin films suggesting the improved efficiency. |
| Databáze: | OpenAIRE |
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