1. STANFORD InGaAs and GaInNAs(Sb) Advanced LIGO Photodiodes David B. Jackrel, Homan B. Yuen, Seth R. Bank, Mark A. Wistey, Xiaojun Yu, Junxian Fu, Zhilong Rao, and James S. Harris, Jr. Solid State Research Lab, Stanford University LSC Meeting – LHO August 16 th, 2005 LIGO-G050435-00-Z

2. STANFORD 2 / 18 Outline l Introduction l AdLIGO Photodiode Specifications l Device Materials l Device Design l GaIn(N)As(Sb) Materials & Device Results l Conclusion

3. STANFORD 3 / 18 Advanced LIGO Schematic Power Stabilization Auxiliary Length Sensing High-Speed Low Power  Commercial Device 180 W Low Noise I ph ~ 200 mA Commercial Device?

4. STANFORD 4 / 18 LIGO AS-Photodiode Specifications I-LIGOAdvanced LIGO Detector Bank of 6PDs DC - Readout RF – Readout Steady-State “Power” (mW) 600 30 – 100  (same as DC) Operating Frequency 30 Mhz 100 kHz200 MHz Quantum Efficiency  80%  90%  (same as DC) Damage Threshold ( MW/cm 2 ) < 5< 50  (same as DC)

5. STANFORD 5 / 18 1 eV Materials: InGaAs & GaInNAs GaInNAs(Sb) 25% InGaAs 1064nm light  1.13eV º Ge

6. STANFORD 6 / 18 Metamorphic-InGaAs vs. GaInNAs Double Heterostructres 1m1m 2m2m I- GaInNAs(Sb) 8% In, 2% N, (4% Sb) I- In 0.25 Ga 0.75 As l GaInNAs(Sb) MBE growth with RF-Plasma source for N l Sb surfactant effects improve thin strained nitride films

7. STANFORD 7 / 18 Conventional PD Adv. LIGO Back-Illuminated PD l High Power l Linear Response l High Speed Back-Illuminated Photodiodes

8. STANFORD 8 / 18 Outline l Introduction l GaIn(N)As(Sb) Materials and Device Results l Materials Characterization Summary l Dark Current l Bandwidth l Quantum Efficiency l Saturation Power Level l Conclusion & Future Work

9. STANFORD 9 / 18 Materials Characterization Summary PL Intensity (A.U.) Relaxation (%) Absorption (%) TDD (cm -2 ) Trap Density (cm -3 ) MM- InGaAs 24.188.996%1e72.0e13 GaInNAs 2.24.360%~1e51.1e14 GaInNAs (w/ Deflection Plates) 8.5-70%~3e5- GaInNAsSb (w/ D.P.) 1.144.680%< 1e5- XRD-Reciprocal Space Map (224) Photoluminescence (PL) Spectra Absorption Spectra Deep-Level Transient Spectroscopy (DLTS) A B A B Spectral Cathodoluminescence (CL) Imaging to determine Threading Dislocation Density (TDD) IntensityPeak Energy

10. STANFORD 10 / 18 Dark Current Density: GaIn(N)As(Sb) Devices - J dk (A/cm 2 )

11. STANFORD 11 / 18 MM-InGaAs: 3dB Bandwidth  = 3 mm MM-InGaAs PD BW ~ 1/RC BW > 200 MHz  = 400  m P sat ~ 10 mW AdLIGO PD Specifications: 3-dB Bandwidth Sat. Power DC-Scheme : 100 kHz 30 – 100 mW RF-Scheme: 200 MHz AdLIGO RF-Readout Challenging for PDs!

12. STANFORD 12 / 18 InGaAs & GaInNAs PDs – IQE (w/ FCA & Incomplete Absorption) AdLIGO Requirement Int.

13. STANFORD 13 / 18 GaIn(N)As(Sb) PD QE GaInNAs GaInNAsSb* InGaAs (* scaled to account for FCA in thick substrates) Int.

14. STANFORD 14 / 18 Photodiode Saturation Power GaInNAs GaInNAsSb* InGaAs Bias V: 3 ~ 8 V (* scaled to account for FCA in thick substrates) LIGO GW-PD Requirement

15. STANFORD 15 / 18 Photodiode Results Summary Materials ParametersPhotodetectors Abs. (%) Relax. (%) TDD (cm -2 ) Trap Density (cm -3 ) IQE (%) J dk (  A/cm 2 ) MM- InGaAs 96%88.91e72.0e1375%~ 10 GaInNAs 60%4.3~1e51.1e1462%~ 0.1 GaInNAsSb 80%44.6< 1e5- 56% (scaled) ~ 1

16. STANFORD 16 / 18 Conclusion AdLIGO AS-PD Specification B-I PDs Developed at Stanford F-I PDs Commercial devices Saturation Power (mW) 30 - 100~ 150100 ~ 200 Quantum Efficiency 90 % 75 % (  90 % w/ substrate removal) ~ 90 % Bandwidth (MHz) 100 kHz (  200 MHz RF-scheme) 4 1 ~ 10 Damage Threshold (MW / cm 2 ) < 5 (w/ 1  s shutter & 1 mm spot) Modeling ~ 3 (w/ 1 mm spot) Modeling ~ 0.4 (w/ 1 mm spot)

17. STANFORD 17 / 18 AdLIGO Photodiode Development: Future Work l Substrate removal l  90 % QE l High-Temperature Packaging l LLO or LHO Damage Threshold Tests? l Compatible with other experiments (GEO-600, MIT?) l Surface Uniformity & Noise Characterization l GEO-600 l Multi-Element Sensors? l Additional pointing information l Spatial mode information l Fabricate AdLIGO Photodiodes

18. STANFORD 18 / 18 Acknowledgements l National Science Foundation (NSF); this material is based on work supported by the NSF under grants 9900793 and 0140297. l Aaron Ptak, Manuel Romero and Wyatt Metzger at National Renewable Energy Labortatory (NREL) in Golden, CO l Gyles Webster at Accent Optical in San Jose, CA l Thank You

19. STANFORD Extra slides

20. STANFORD 20 / 18 Molecular Beam Epitaxy (MBE) l Effusion cells for In, Ga and Al l Cracking cell for As and Sb l RF-Plasma N cell Deflection Plates (DP) on Plasma Source  protect growth surface from ion damage + V - V substrate Nitrogen cell

21. STANFORD 21 / 18 Double-Heterostructure PIN Photodiodes N- and P- transparent  Absorption occurs in I-region where E-field is large n- i- p- 0 1 2 3  m 2 eV 1 0 -2 InGaAs DH-PIN device simulated by ATLAS (Silvaco) light

22. STANFORD 22 / 18 Lattice-Mismatched Epitaxy misfit dislocation a film a substrate a film > a substrate h < h c h > h c h c  critical thickness

23. STANFORD 23 / 18 Materials Results Summary PL Intensity (A.U.) Relaxation (%) Absorption (%) TDD (cm -2 ) Trap Density (cm -3 ) MM- InGaAs 24.188.996%1e72.0e13 GaInNAs 2.24.360%~1e51.1e14 GaInNAs (DP) 8.5-70%~3e5- GaInNAsSb 1.144.680%< 1e5-