1. A CMOS Photodiode Model
Wei-Jean Liu, Oscal T.-C. Chen
Signal and Media Laboratories,
Dept. of Electrical Engineering,
National Chung Cheng University,
Chia-Yi, 621Taiwan
Li-Kuo Dai, Ping-Kuo Weng, Kaung-Hsin Huang, Far-Wen Jih
Solid-State Devices Materials Section,
Materials & Electro-Optics Research Division,
Chung-Shan Institute of Science & Technology,
Tao-Yuan, Taiwan

2. Outline Introduction Physics Phenomenon Analysis Measurement Setup
Simulation and Experiment Comparison
Conclusion

3. Introduction CMOS technology
-Lower power consumption and compatible process.
Goal
-To achieve a general CMOS photodiode model.

4. Photo Current

5. CMOS Photodiode Construction

6. Parameter Definition Photon Flux Carrier Generation Rate
Absorption Coefficient
*Ref. D. Schroder, “Semiconductor Material and Device Characterization”, John Wiley and Sons, Inc., pp499, 1990

7. Photon Current Equation
N-type Semiconductor
Depletion Region
P-type Semiconductor
Total Current
*NOTE : Jdark is the rest term when incident power is zero.

8. Boundary Condition(I)
-Surface
Top
Bottom
*NOTE : Sp(n) is surface recombination velocity of the hole(electron) in the N-type(P-type) semiconductor surface and the value is simplified to limit to infinite.

9. Boundary Condition(II)
-Depletion Region Edge

10. Boundary Condition(III)
-Between Different Layers
Current Density Continuity
Minority Carrier Concentration Continuity

11. Simulation Results

12. Simulation Results(Cont’d)
Nwell-Epi-Psubstrate
Ndiffusion-Pwell-Epi-Psubstrate

13. Measurement Setup

14. Measurement Procedure
Standard Detector X
Test Chips

15. Experiments v.s. Simulation

16. Surface Recombination Velocity @ 0

17. Surface Recombination Velocity @ ∞

18. Surface Recombination Velocity Effect

19. Reference(I)
Ref.
[1]“Semiconductor Material and Device Characterization”, D. Schroder, John Wiley and Sons,Inc., pp233, pp364, 1990

20. Reference(II)
Ref.
[1]“Physics of Semiconductor Devices ”, S. M. Sze, , New York: John Wiley and Sons, 1980.

21. Reference(III)

22. Reference(IV)

23. Conclusion
A CMOS photodiode model useful in all kinds of structures was accomplished.
This proposed photodiode model would be useful in various circuit simulators to understand the responses of the CMOS photodiodes.