1. 1 ME 381R Lecture 13-14 Semiconductor Devices and Thermal Issues Dr. Li Shi Department of Mechanical Engineering The University of Texas at Austin Austin, TX 78712 www.me.utexas.edu/~lishi lishi@mail.utexas.edu Reading: 1-7-1 & Ch. 7 in Tien et al.

2. 2 p-n Junction w/o Bias Depletion Region

3. 3 Biased p-n Junction

4. 4 Metal-Oxide-Semiconductor (MOS) Capacitor  : Electron Affinity  Work Function Energy Band Diagram before making contact n-type

5. 5 MOS Capacitor W/O Bias (Special Case:  M =  S ) Energy Band Diagram after making contact

6. 6 Accumulation and Depletion of Majority Carriers VGVG ViVi eV G VSVS Block Charge Diagram Very thin

7. 7 Inversion Layer: C majority carrier >C minority carrier

8. 8 Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET)

9. 9 Ideal MOSFET V G >0

10. 10 Pinch-Off & IV

11. 11 Thermal Circuit Particle transport theory Fourier ’ s law of heat conduction

12. 12 Joule Heating in High-Field Devices Localized heat generation near the pinch-off point

13. 13 X-Y-Z Actuator Thermometry of Nanoelectronics Sample Temperature Sensor Laser Atomic Force Microscope (AFM) + Thermal Probe Cantilever Deflection Sensing Thermal X T Topographic X Z Scanning Thermal Microscope:

14. 14 Microfabricated Probes Pt-Cr Junction Shi, Kwon, Miner, Majumdar, J. MicroElectroMechanical Sys., 10, p. 370 (2001) 10  m Pt Line Cr Line Tip Laser Reflector SiN x Cantilever

15. 15 Self Heating Effect on I-V

16. 16 Optical Phonon Emission at High Field

17. 17 Heat Transfer Path

18. 18 Governing Equations for Electro-Thermal Simulation of Devices

19. 19 Example

20. 20 Computation Scheme

21. 21 Results

22. 22 Electric Field

23. 23 Electron Temperature

24. 24 Phonon Temperature