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Số người truy cập: 107,039,186

 Vertically-Aligned of Sub-Millimeter Ultralong Si NanowireArrays and Its Reduced Phonon Thermal Conductivity
Tác giả hoặc Nhóm tác giả: Chia-Yun Chen,
Duong Hong Phan,
Cheng-Chou Wong,
and Ta-Jen Yen
Nơi đăng: Journal of The Electrochemical Society; Số: 158;Từ->đến trang: D302-D306;Năm: 2011
Lĩnh vực: Khoa học; Loại: Bài báo khoa học; Thể loại: Quốc tế
TÓM TẮT
Well-aligned of single crystalline silicon nanowires (SiNWs) arrays are synthesized using Ag-assisted electroless etching processes.By examining a wide range of reaction periods from 1 min up to 12 h, our experimental results show that the lengths of fabricatedSiNWs do not maintain the linear relationship with the reaction period but feature three evident transitions instead. We find that thediffusion of HF through Ag dendrites is the rate-limiting step for maintaining the galvanic reaction of etching processes. To over-come these limitations, we report a simple and controllable route employing HNO3=AgNO3=HF electrolyte solutions, whichenables SiNW lengths ranging from several nanometers up to a few hundred micrometers to become linearly dependent on the reac-tion time. Transmission electron microscopy studies reveal that the SiNWs fabricated by this approach are single crystalline along[100] in axial direction with relatively rough surfaces. In addition, we further measure the thermal conductivities of SiNW arrayswith various lengths at 300 K. The resulting value of thermal conductivity in SiNW arrays is only 44% in comparison with bulk Si(100) substrates; that is attributed to the effects of decreased area of phonon transport, as well as increased phonon scattering.
ABSTRACT
Well-aligned of single crystalline silicon nanowires (SiNWs) arrays are synthesized using Ag-assisted electroless etching processes.By examining a wide range of reaction periods from 1 min up to 12 h, our experimental results show that the lengths of fabricatedSiNWs do not maintain the linear relationship with the reaction period but feature three evident transitions instead. We find that thediffusion of HF through Ag dendrites is the rate-limiting step for maintaining the galvanic reaction of etching processes. To over-come these limitations, we report a simple and controllable route employing HNO3=AgNO3=HF electrolyte solutions, whichenables SiNW lengths ranging from several nanometers up to a few hundred micrometers to become linearly dependent on the reac-tion time. Transmission electron microscopy studies reveal that the SiNWs fabricated by this approach are single crystalline along[100] in axial direction with relatively rough surfaces. In addition, we further measure the thermal conductivities of SiNW arrayswith various lengths at 300 K. The resulting value of thermal conductivity in SiNW arrays is only 44% in comparison with bulk Si(100) substrates; that is attributed to the effects of decreased area of phonon transport, as well as increased phonon scattering.
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