Gated Silicon Nanowires for Thermoelectric Applications Emilio - PowerPoint PPT Presentation

Gated Silicon Nanowires for Thermoelectric Applications Emilio Codecido Mentor: Ben Curtin Faculty: John Bowers, Electrical and Computer Engineering UCLEADS, UC Santa Barbara 08-22-2012

門控矽納米線 for 热电 Applications Emilio Codecido Mentor: Ben Curtin Faculty: John Bowers, Electrical and Computer Engineering UCLEADS, UC Santa Barbara 08-22-2012

Thermoelectrics Applications

Energy Conversion Efficiency Power Factor Thermal conductivity Thermal conductivity

Doped Silicon Nanowires Carrier mobility Carrier Carrier charge density N-type doped silicon

Gated Silicon Nanowires mobility density charge • Approach: Gate (conductor) + + + + + + + + + + + + + + + + + + + + + + + + + + + + Insulator - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Pure Si nanowire

Measuring the Properties of the Nanowire Seebeck: Electrical Conductivity: Top View 10 μ m Heat Source 4 probes resistance Nanowire Gate Thermometers and measurement voltage pins

Measuring the Seebeck of the Nanowire Seebeck:

170.5 91.5 170.0 91.3 Line 1 169.5 91.0 Resistance 2 (Ohm) Resistance 1 (Ohm) Line 2 169.0 90.8 168.5 90.5 168.0 90.3 167.5 90.0 167.0 89.8 166.5 89.5 166.0 89.3 165.5 89.0 23 24 25 26 27 28 29 30 31 32 33 Lines Temperature (°C)

Measuring the Seebeck of the Nanowire Seebeck:

10 μ m 1 mm

Seebeck: Seebeck Data on Si Sheet ∆T vs. Heater Current ∆V vs. Heater Current 7.00 1.40E-03 6.00 1.20E-03 run 1 run 1 5.00 1.00E-03 run 2 ∆T (K) run 2 4.00 ∆V (V) 8.00E-04 3.00 6.00E-04 2.00 4.00E-04 1.00 2.00E-04 0.00 0.00E+00 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 Heater Current ( A) Heater Current (A) Seebeck: ∆V vs. ∆T 1.40E-03 Seebeck Expected: ~-200 μ V/K • 1.20E-03 run 1 1.00E-03 • Seebeck 1: -211.8 μ V/K | ∆V| ( V) run 2 8.00E-04 Seebeck 2: -212.5 μ V/K • 6.00E-04 4.00E-04 • Don’t get excited yet! 2.00E-04 Remember, measuring silicon 0.00E+00 0 1 2 3 4 5 6 7 sheet, not silicon nanowires… ∆T (K)

Conclusions : • Seebeck measurement is very precise, but still not sure how accurate. • Measurement routine needs to be tested with nanowires. Future Work: • Measure nanowires • Power factor vs. gate voltage FINALLY…

門控矽納米線 Gated Silicon Nanowires for for 热电 Applications Thermoelectric Applications Emilio Codecido Mentor: Ben Curtin Faculty: John Bowers, Electrical and Computer Engineering UCLEADS, UC Santa Barbara 08-22-2012

Acknowledgments • Ben Curtin • Prof. Bowers • UCLEADS staff