Doping of Al-catalyzed Vapor-liquid-solid Grown Si Nnanowires
- PDF / 1,268,799 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 49 Downloads / 154 Views
1018-EE05-20
Doping of Al-Catalyzed Vapor-Liquid-Solid Grown Si Nnanowires Sung Jin Whang1, Sung Joo Lee1, Wei Feng Yang1, Hai Chen Zhu1, Han Lu Gu1, Byung Jin Cho1, and Yun Fook Liew1,2 1 Electrical and Computer Engineering, National University of Singapore, Block E4A #02-04 Engineering Drive 3, Singapore, Singapore, 117576, Singapore 2 Data Storage Institute, Singapore, 117608, Singapore ABSTRACT We successfully synthesized high quality single crystal Si nanowires using Al catalyst via vapor-liquid-solid (VLS) mechanism, having diameters ranging from 10 to 200 nm with 10~20
㎛ of length. Characterization of physical and chemical properties of Al-catalyzed Si nanowires
using transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) analysis showed that single crystal Si nanowires can be grown with Al-catalyst at 540 and selective etching of Al existing at the tip of nanowire can provide metal-free Si nanowires that are compatible with conventional Si-based IC process. By using plasma doping method, it was confirmed that the doping level can be controlled and the boron was successfully introduced on Si substrate with 3×1022 /cm3 of peak doping concentration.
℃
INTRODUCTION Among the attractive advantages of bottom-up grown 1-dimentional semiconductor nanowires as a novel building block, the ability to predict and control the chemical composition and electronic doping level of semiconductor nanowires is a key feature for nanoscale device applications, using well-known knowledge obtained from the planar silicon technology. In this work, we studied the both n- and p-type doping process and their effects on the morphology and microstructure of Si nanowires by using complementary metal-oxide semiconductor (CMOS) compatible Al catalyst. EXPERIMENT Al seeding layer of 10nm was deposited on SiO2 (100 nm) wafer by e-beam evaporator and thus the wafer was transferred into a chemical vapor deposition (CVD) chamber. The base pressure of the chamber was less than 30 mtorr and the growth temperature was ~ 540 . Single crystalline Si nanowires were synthesized for 4min with 200sccm of N2, 200 sccm of SiH4 (100 %) gases. The partial pressure of SiH4 was maintained at 20 torr. In this experiment, two different methods were used to introduce dopants into the nanowires. First method is co-flow doping, meaning that n- or p- type dopant is flowing during the synthesis of nanowire. The other method is post-synthesis plasma n- or p-type doping for nanowires. To compare the co-flow and post-synthesis plasma doping, undoped Si nanowires were synthesized using CMOS compatible Al seeding layer. In-situ RF plasma PH3 and B2H6 doping were carried out for 1min at 440 under H2 and PH3 (1 %) gases for n-type dopants and H2 and B2H6 (0.8 %) for p-type dopants. Finally, the sample was cooled down at the loadlock chamber for 10min at room temperature.
℃
℃
For TEM analysis, the nanowires grown at above conditions were dispersed on Cu grid and TEM images of our synthesized nanowires were
Data Loading...
