Nano Lett., VolLICATION IN SOLAR CELLS(LIGHT ABSORPTION)

Advanced photon management, involving both absorption enhancement and reflection reduction, is critical to all the photovoltaic devices. Si:H nanowire (NW) and nanocone (NC) arrays.
On(100)
On(110)
Nanotechnology 19 (2008) 365609 (4pp)
SILICON NANOTUBES

Growth of SiNTs is based on a dual RF plasma treatment technique: 1.Nitrogen gas as plasma generation & oxidized Si substrates as Si source; 2. This silicon substrate is heated to 500℃ after the chamber filled with N2; 3. Two RF plasma generators (1 and 2) are uesd for the growth SiNTs； 4. Bias voltages generated by the plasmas will induce bombardments of N2+ ions and initiate sputtering of these plasma wires and the substrates.
J. Vac. Sci. Technol. B 26(1)Jan/Feb 2008
ULTRATHIN SILICON NANOWIRES

AFM lithography:
1.Passivate the silicon samples with HF solution; 2. The negative voltage pulses applied at ambient to the conductive AFM tip removes the passivating H-layer and induces the local formation of oxide mask under the tip(displacing the tip according to a predefined design). 3. The oxide pattern is transferred to the silicon sample by selective wet etching in TMAH(四甲基氢氧化氨,不腐蚀SiO2),and remove the mask.

O2 andCHF3
Between 400 and 650nm:absorption >93%(nanocone), ~75%(nanowire), ~64%(thin film).
APPLIED PHYSICS LETTERS 95, 243113 (2009)
APPLICATION IN SOLAR CELLS(LIGHT ABSORPTION)

Diameters ∼50–80 nm ; wall thicknesses∼10–15 .
Nanotechnology 21 (2010) 055603 (6pp)
SILICON NANOTUBES


Synthesis of silicon nanotubes with cobalt silicide ends using anodized aluminum oxide template. Open at one end and connected with CoSi ends of the same diameter.
width:95nm;thick:8nm
JOURNAL OF APPLIED PHYSICS 107, 096105 (2010)
ULTRATHIN SILICON NANOWIRES

Silver catalyzed ultrathin silicon nanowires by CVD :
1.Clean and obtain oxide free and hydrogen terminated surface; 2.Evaporate(Alfa-Aesar) less than a monolayer silver and elevate the temperature to form silver nanoparticales; 3.UHV-CVD process(below 500℃ ,indicating the vapor-solid-solid); 4.HF solution(1%)remove oxide; 5.铁氰化钾和硫代硫酸钠混合水溶液remove silver.
SILICON NANOTUBES
SiNT growth is manifested in a temperature window of 320 ℃-450℃ for AuNPs less than 15 nm in diameter and at 450 ℃ for AuNPs within 16-22nm. 硅纳米线采用tip生长模式， 硅纳米管采用bottom生长模式
SILICON NANOTUBES

The density and length of these SiNTs vary with the dc bias voltages on the substrates, and the techniques of supplying the Cu catalysts. VLS growth model.
The Applications of Silicon Nanowires
——Summary of the passing semester
CONTENTS:

Synthesizing Silicon Nanotubes & Ultrathin Silicon Nanowires Applications of Silicon Nanowires ,Nanotube ,etc. 1. Solar Cells; 2. Photoelectrochemical cell(PEC); 3. Anodes for Lithium Ion Batteries; 4. Thermoelectric Properities; 5.Sensing;
For SiNWs with thickness of 5000nm ,its absorption is better than thin film with the same thickness when :P is set between 250-1200nm; And the ratio of D to P should be >0.5 (or more specifically ~ 0.8) for the optimized solar energy harvesting.
On BSG & OnSiOx/Si subract
SiNT growth is manifested in a temperature window of 320℃-450℃ for AuNPs less than 15 nm in diameter and at 450℃ for AuNPs within 16-22nm.
Nano Lett. 2010, 10, 3823-–3827
APPLICATION IN SOLAR CELLS(LIGHT ABSORPTION)

Ge nanopillar arrays
D1=60nm; D2=130nm.
The Ge DNPL array : 95- 100%absorption for λ=900- 300 nm. What will happen if this structure of Ge Nanopillar is apllied to silicon?!
polycrystalline
ACS NANO vol. 4 ▪ NO. 4 ▪ 1805–1812 ▪ 2010
SILICON NANOTUBES



Si 1D structures on amorphous substrates via a NP-mediated route：
Growth via dissociative adsorption of SiH4 on gold NPs. In H2 plasma treatment,Si 1D growth happends below 320℃(above 480℃ for O2 plasma).
J. AM. CHEM. SOC. 9 VOL. 130, NO. 29, 2008 9225
APPLICATION IN SOLAR CELL
SiNWs core–shell radial p–n junction solar cell
Single crystalline n-Si NW core; Polycrystalline p-Si shell. Length:18 um; Core diameter:50-100nm; Shell thickness:150nm. First, aqueous electroless etchingsingle crystalline SiNW core; Then depositing Si shell using disilane(with dopant gas), crystallized with RTA. Voc=0.29V;Jsc=4.28mA/cm2;FF=0.33;Efficiency=0.45%