Slide 1OutlineSlide 3Silicon p-i-n NanowiresContact Formation by using LithographyDiode characteristicIV CurvesSlide 8ConclusionsSupplementarySlide 11Capacitance Equations of Core shellCapacitance Equations of Core shellOnur Ergen “Coaxial Silicon Nanowires as Solar Cells and Nanoelectronic Power Sources”EE235Student Presentation 2 march 2009Electirical Engineering and computer science University of California, Berkeley [email protected]Literature review: “Coaxial Silicon Nanowires as Solar Cells and Nanoelectronic Power Sources”Advantage of this core/shell architecture.Diode characteristic of p-i-n nanowire core shell strucuture.Photovoltaic properties of the p-i-n coaxial silicon nanowire diodes.Silicon p-i-n NanowiresAdvantage of this core/shellstructure,◦Charge separation along radial vs.longer axial direction◦Photo generated carriers can reach the p-i-n junction without bulk recombination.◦Material quality can be lowerGrown by VLS followed by CVDSingle crystalline core, polycrystalline shellTian, B.; Zheng, X.; Kempa, T.; Fang, Y.; Yu, N.; Yu, G.; Huang, J.; Lieber, C. M. Nature, 2007, 449, 885-890.Contact Formation by using LithographyTian, B.; Zheng, X.; Kempa, T.; Fang, Y.; Yu, N.; Yu, G.; Huang, J.; Lieber, C. M. Nature, 2007, 449, 885-890.Diode characteristic Highly conductive n-shell eliminate potential drop along the shell,◦enabling carrier separation and collection when illuminated.“ ‘AND’ and ‘OR’ diode logic gates.Ideality factor N ,◦Np-i-n=1.96 for Np-n=4.52p-i-n diode breaks down much larger. Low temperature high breakdown voltage.Tunnelling or leakage currents are more significiant for p-nIV CurvesTian, B.; Zheng, X.; Kempa, T.; Fang, Y.; Yu, N.; Yu, G.; Huang, J.; Lieber, C. M. Nature, 2007, 449, 885-890.Illuminated under AM1.5 conditionsVoc = 0.260V;V is essentially independent of length. Isc = 0.503 nA; Ffill = 55.0 %Maximum Power = 72 pW, stable for seven monthsPower Conversion Efficiency = ~ 3%Radial and axial p-i-n structural JscRadial =24 mA cm-2JscAxial =3.5 mA cm-2VocRadial = 0.26VVocAxial =0.29 V Efficiencies ;ηRadial =3.4%ηAxial =0.5%, Radial and Axial Single Nanowire Photovoltaics,B. Tian, T.J. Kempa and C.M. Lieber, "Single Nanowire Photovoltaics," Chem. Soc. Rev. 38, 16-24 (2009)ConclusionsReducing recombination can increase device performance◦Nanowire is 6.6 % efficient at 80 KPossible to used as power sources in nanoelectronics◦Nanowire PV was used to drive a nanowire pH sensor without external power.Controlling the thickness of p-i-n layers have crucial importance for Voc.Tian, B.; Zheng, X.; Kempa, T.; Fang, Y.; Yu, N.; Yu, G.; Huang, J.; Lieber, C. M. Nature, 2007, 449, 885-890.Supplementary Nanowire pH sensorCapacitance Equations of Core shellCapacitance Equations of Core
View Full Document
Unlocking...