High-Electron-Mobility SiGe on Sapphire Substrate for Fast Chipsets
High-quality strain-relaxed SiGe films with a low twin defect density, high electron mobility, and smooth surface are critical for device fabrication to achieve designed performance. The mobilities of SiGe can be a few times higher than those of silicon due to the content of high carrier mobilities...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2015-01-01
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| Series: | Advances in Condensed Matter Physics |
| Online Access: | http://dx.doi.org/10.1155/2015/785415 |
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| Summary: | High-quality strain-relaxed SiGe films with a low twin defect density, high electron mobility, and smooth surface are critical for device fabrication to achieve designed performance. The mobilities of SiGe can be a few times higher than those of silicon due to the content of high carrier mobilities of germanium (p-type Si: 430 cm2/V·s, p-type Ge: 2200 cm2/V·s, n-type Si: 1300 cm2/V·s, and n-type Ge: 3000 cm2/V·s at 1016 per cm3 doping density). Therefore, radio frequency devices which are made with rhombohedral SiGe on c-plane sapphire can potentially run a few times faster than RF devices on SOS wafers. NASA Langley has successfully grown highly ordered single crystal rhombohedral epitaxy using an atomic alignment of the [111] direction of cubic SiGe on top of the [0001] direction of the sapphire basal plane. Several samples of rhombohedrally grown SiGe on c-plane sapphire show high percentage of a single crystalline over 95% to 99.5%. The electron mobilities of the tested samples are between those of single crystals Si and Ge. The measured electron mobility of 95% single crystal SiGe was 1538 cm2/V·s which is between 350 cm2/V·s (Si) and 1550 cm2/V·s (Ge) at 6 × 1017/cm3 doping concentration. |
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| ISSN: | 1687-8108 1687-8124 |