Noise as a diagnostic tool in materials and electronic devices

Instructor: Prof. L. K. J. Vandamme

Affiliation: Eindhoven University of Technology, Department of Electrical Engineering

Duration: 12 hours

Period: March 9 - 23, 2005

Place: Dipartimento di Ingegneria dell'Informazione: Elettronica, Informatica, Telecomunicazioni, via G. Caruso, meeting room, ground floor

Credits: 3

Final test: yes

Contacts: Prof. Massimo Macucci

Contents:

  1. Introduction
    1. Short history of noise research, some objectives and definitions, measuring set up
  2. Noise sources, origins, and remedies
    1. Noise sources: thermal, shot, generation-recombination, RTS (random telegraph signal noise) and 1/f noise
    2. Noise equivalent circuits for passive components
  3. Resistance fluctuations in networks and continuous media
    1. Sensitivity coefficient for two ports
    2. Sensitivity coefficient for four ports
    3. Current crowding increases the effect of conductance fluctuations
  4. Experimental facts on 1/f noise in metals and semiconductors
    1. Hooge’s empirical relation for the 1/f noise
  5. Noise in electronic devices: Resistors, MOSFET, Diodes, BJT
    1. Resistors (Au-layers, poly Si, poly SiGe, thick film resistors)
    2. Diodes (shot noise, 1/f and RTS noise; perimeter or bulk contributions; faster diodes are noisier)
    3. MOSFETs
    4. Flicker noise in MOSFETs, is it a surface or bulk effect; is it due to trapping or due to mobility fluctuations?
    5. Circuit oriented noise equations in terms of the 1/f noise parameter for biasing conditions in the Ohmic/Saturation/or Sub-threshold region
    6. Faster is noisier
    7. Review of experimental results
    8. Misunderstandings about 1/f noise in MOSFETs
    9. RTS noise is an additional number-fluctuation noise on top of 1/f noise
    10. Number fluctation/mobility fluctuation controversy; controversy about the bulk or surface origin
    11. BJTs and HBTs
    12. 1/f noise in bipolars (perimeter?)
    13. Corner frequency: a figure of merit?
    14. Is the ratio of the corner frequency to the transition frequency a new figure of merit?
    15. An equivalent circuit: problems and formulas
    16. How to measure the dominant noise source by coherence techniques
    17. Experimental results on poly-emitter BJTs, HBTs
    18. Noise figure at medium frequencies
    19. Discussion and conclusions
  6. 1/f Noise as a diagnostic tool for quality evaluation of materials and devices
    1. Different noise types such as: shot noise, burst noise or RTS, generation recombination noise and the omnipresent 1/f noise have different meanings in view of reliability diagnostics
    2. Current crowding makes the omnipresent 1/f noise a sensitive quality indicator of external and internal contacts in materials and devices (e.g. submicron-MODFETs, conductive adhesives, thin film transistors, poly silicon layers)
    3. 1/f noise in contacts (with and without complications)
    4. Low frequency noise as an indicator of reliability problems will be discussed in diode type devices (e.g. p-n junctions, Schottky-barriers and bipolars) and in resistor type devices
    5. Some case studies: polymer transistor, nanoparticle dielectrics, MESFETs, MODFETs, solar cells and LEDs
    6. The correlation between noise in devices and the reliability is explained
    7. Noise measurements are often more sensitive and less destructive than classical tests after accelerated life tests
  7. Low frequency noise measuring set ups
    1. Time domain analysis for non-Gaussian noise mixed up with Gaussian noise (RTS with e.g. 1/f noise) and analysis in frequency domain
    2. Resistance fluctuations from measured voltage or current fluctuations
    3. Calculated current noise spectral density from the voltage noise spectral density (3 cases)
    4. Noise characterization of amplifiers
    5. Instrumentation
    6. Telecommunication
    7. Voltage amplifiers in series
    8. Amplifier choice, low noise current or voltage amplifier, transformer amplifier, or a correlation measurement
    9. Sample design based on a high corner frequency value, four contacts on a sample is not always a guarantee of contact noise suppression
    10. Measuring setup (band pass filtering or line spectra, FFT)
    11. Shielding
  8. Exercises
  9. References