Noise Sources in Semiconductor Detectors S W Mc
- Slides: 12
Noise Sources in Semiconductor Detectors S W Mc. Knight and C A Di. Marzio
Sources of Noise • Johnson Noise (Nyquist noise) – Random thermal fluctuations of electrons in resistive elements • Shot Noise – Statistical fluctuations in photo-electron generation • Generation-Recombination Noise – Statistical fluctuations in current carrier generation due to photons and thermal excitation and recombinations • 1/f Noise – Low-frequency noise related to interfaces and contacts
Johnson (Nyquist) Noise Connection between fluctuations and dissipation in system: Brownian motion: = slowly varying external force F(t) = random thermal force drives system back towards equilibrium (v=0 for =0) F’(t) = fluctuation force
“Frictional” force Ensemble average: For time scales slow compared to thermal fluctuations:
Electrical Analogy Circuit with self-inductance L: Current flows under influence of external emf + fluctuating thermal emf: V + V(t) Average thermal force opposes current, drives system toward thermal equilibrium (I=0) Fluctuating thermal force creates thermal noise
Circuit Equation V R V
Fluctuation-Dissipation Theorem “Frictional” force is related to the time correlation of the rapidly varying random fluctuation force
Resistance and Noise Time-correlation of random thermal voltage fluctuations:
Spectral Density of Autocorrelation Function
Voltage and Current Thermal Fluctuations “Johnson” or “Nyquist” noise
Shot Noise or G-R Noise From Poisson statistics:
Noise in Photoconductors
Quantizing noise (quantization noise):
Problems of sound pollution
Example of noise pollution
Solutions to noise pollution
Print sources of information
Water resources important
Streaming current
Where are feature detectors located
Giant wave detectors murmurs universe
Frontier detectors for frontier physics
Photo detectors
Vhv voltage detectors
Feature detectors ap psychology
