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Advanced LIGO Photodiode Development ______

Advanced LIGO Photodiode Development ______. David Jackrel, PhD Candidate Stanford University Dept. of Materials Science and Engineering James S. Harris Hannover, Germany August 20 th , 2003 LIGO-G030495-00-Z. Outline. Motivation & Introduction AdLIGO PD Specifications

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Advanced LIGO Photodiode Development ______

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  1. Advanced LIGO Photodiode Development______ David Jackrel, PhD Candidate Stanford University Dept. of Materials Science and Engineering James S. Harris Hannover, Germany August 20th, 2003 LIGO-G030495-00-Z

  2. Outline • Motivation & Introduction • AdLIGO PD Specifications • Device Materials and Design InGaAs vs. GaInNAs • Device Results • Thinned Device QE • InGaAs & GaInNAs I-V • 2m Thick GaInNAs Absorption • Predictions

  3. Auxiliary Length Sensing Power Stabilization Advanced LIGO Schematic

  4. e.g. 1W/0.70=1.43W Resonating Tank Circuit Thinned Substrate Photodiode Specifications

  5. GaInNAs vs. InGaAs GaInNAs 25% InGaAs 53% InGaAs 1064nm light  1.13eV

  6. InGaAs vs. GaInNAs PD Designs 2 m GaInNAs lattice-matched to GaAs!

  7. Rear-Illuminated PD Advantages • High Power • Linear Response • High Speed Conventional PD Adv. LIGO Rear-Illuminated PD

  8. Development Flow-Chart

  9. Thinned Device QE (10mW)

  10. Thinned Device QE (w/ 100m, 3e17cm-3 Substrate)

  11. DC Device Efficiency (w/ ARC) Ext. Efficiency Bias (Volts) Optical Power (mW)

  12. InGaAs vs. GaInNAs Dark Current

  13. InGaAs vs. GaInNAs Dark Current

  14. GaInNAs Device Transmission

  15. Predictions (I think we can do it…)

  16. Laser Interferometer Gravitational Wave Observatory (LIGO) 180W 1064nm

  17. MBE Crystal Growth N Plasma Source • Effusion cells for In, Ga, Al • Cracking cell for As • Abrupt interfaces • Chamber is under UHV conditions to avoid incorporating contaminants • RHEED can be used to analyze crystal growth in situ due to UHV environment • T=450-600C Atomic source of nitrogen needed  Plasma Source!

  18. Heterojunction Band Gap Diagram InAlAs and GaAs transparent at 1.064m  Absorption occurs in I-region (in  E-field ) p- i- n- N-layer: In.25Al.75As or GaAs Eg2=2.0-1.4eV I-layer: In.25Ga.75As, or Ga.88In.12N.01As.99 Eg1=1.1eV P-layer: In.25Al.75As or GaAs Eg2=2.0-1.4eV

  19. Full Structure Simulated by ATLAS

  20. - N+ GaAs Substrate - Epitaxial Layers - Au Contacts - Polyimide Insulator - SiNx AR Coating - AlN Ceramic High Efficiency Detector Process (1) 2. Etch Mesa – H2SO4:H2O2:H20 and Passivate in (NH4)2S+ 1. Deposit and Pattern P-Contact 4. Flip-Chip Bond 3. Encapsulate Exposed Junction

  21. - N+ GaAs Substrate - Epitaxial Layers - Au Contacts - Polyimide Insulator - SiNx AR Coating - AlN Ceramic High Efficiency Detector Process (2) 5. Thin N+ GaAs Substrate 7. Saw, Package and Wire-Bond 6. Deposit AR Coating & N-Contact

  22. Free-Carrier Absorption N+ S-I

  23. Free-Carrier Absorption

  24. Free-Carrier Absorption

  25. Free-Carrier Absorption 5e17cm^-3

  26. Thinned Device QE (w/ ARC)

  27. Photodiode Specifications

  28. Thinned Device Photocurrent

  29. DC Device Response

  30. DC Device Efficiency

  31. Free-Carrier Absorption A = 1 – exp(-tsub•fc) , fc = Nd * 3e-18

  32. Surface Passivation Results (2)

  33. (NH4)2S+ Surface States GaAs(111)A GaAs(111)B (Green and Spicer, 1993)

  34. Surface Passivation Results

  35. Large InGaAs Devices, –20V Bias

  36. InGaAs vs. GaInNAs Dark Current

  37. GaInNAs Dark Current

  38. InGaAs Dark Current

  39. GaInNAs H2SO4 vs. (NH4)2S+

  40. GaInNAs H2SO4 vs. (NH4)2S+

  41. Theoretical Saturation Powers

  42. Theoretical Saturation Powers

  43. RC-Circuit Bode Plot 3-dB 30MHz

  44. RC- and LCR- Transmittance RC-Circuit LCR-Circuit

  45. LCR- Circuit Impedance

  46. RC- vs. LCR-Circuits RC- PD acting as a Low-Pass Filter LCR #1- PD // Inductor as a Tuned Band-Pass Filter (with large R=50) LCR #2,3- PD // Inductor as a Tuned Band-Pass Filter (Rs=1)

  47. Transfer Function LCR #3

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