STANFORD Advanced LIGO Photodiode Development ______ 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 – LLO March 22 nd, 2005 LIGO-G Z

STANFORD Outline l AdLIGO Photodiode Specifications l Device Results l Damage Threshold l AdLIGO Devices l Future Directions

STANFORD Advanced LIGO Schematic Power Stabilization Auxiliary Length Sensing

STANFORD Photodiode Specifications LIGO IAdvanced LIGO Detector Bank of 6PDs Power Stabilization Aux. Length (RF) Detection DC - GW Channel Steady- State “Power” 0.6 W200 ~ 300 mA10 – 100 mW30 mW Operating Frequency ~29 MHz100 kHz200 MHz100 kHz Quantum Efficiency  80%  > 80%  90% (300mA)/(0.868A/W * 0.90 QE) = 385mW Resonating Tank Circuit Trades w/ Sensitivity

STANFORD Conventional PDAdv. LIGO Rear-Illuminated PD l High Power l Linear Response l High Speed Rear-Illuminated PD Advantages

STANFORD Materials Analysis – InGaAs/GaAs vs. GaInNAs/GaAs l X-Ray Diffraction l Transmission Electron Microscopy l Surface Roughness Mapping l Photoluminescence l Deep-Level Transient Spectroscopy l Absorption Spectra l Etc.

STANFORD Device Internal Quantum Efficiency (Low Power ~ 50 mW)

STANFORD External Quantum Efficiency – Thick Substrate Ext. Efficiency Optical Power (mW) Bias (Volts)

STANFORD Damage Threshold – LLO Devices (9/23/03) P > 2e6 W/cm 2 (???) (>180 W in 100  m spot)

STANFORD LHO Damaged PDs – Shutter Problems (2/22/05) Damaged Devices Undamaged Devices “…acoustic coupling…” -Robert Schofield

STANFORD LHO Damaged PDs – Shutter Problems (2/18/05) No injected Peak at 280 Hz

STANFORD Rear-Illuminated Damage-Threshold Test

STANFORD Front-Illuminated Damage-Threshold Test

STANFORD AdLIGO Devices Detector Power Stabilization Aux. Length Sensing GW Channel Diameter 3 mm1.5 mm 1 mm (or larger?) Steady-State Power 300 mW100 mW50 mW 3-dB 1/RC Bandwidth 5 MHz 30 MHz (  180 MHz?) 60 MHz Quantum Efficiency  > 80 %80 ~ 90 % Damage Threshold  ?Important?!

STANFORD AdLIGO Devices: Commercial Vendors

STANFORD In Progress / Future Directions l Substrate removal l GaInNAs(Sb) growth (w/ upgraded system) l ARC l 1/f noise experiments Successor - Zhilong Rao l Packaging devices / Testing components l Higher saturation power? (  RF detection?) l Surface uniformity?, Backscatter?, etc.

STANFORD Future Directions – What types of diodes are needed?  Quantum Efficiency?  Damage Threshold?  Saturation Power?  RF detection  AdLIGO laser stabilization  Electronic Noise?  DC  RF? (180 MHz)  Frequency Response?  Commercially available?  Other???

STANFORD XRD Reciprocal Space Map (004) MM-InGaAsGaInNAs

STANFORD Surface Roughness MM-InGaAs RMS = 6.2 nm GaInNAs RMS = 0.8 nm [110][-110]

STANFORD Optimizing Post-Growth Anneal

STANFORD Scanning Photoluminescence Intensity InGaAs: Uniformity: 10.8% GaInNAs Uniformity: 15.9%

STANFORD Scanning PL Intensity Maps InGaAsGaInNAs

STANFORD GaInNAs Temp. Dependent PL: Localization Energy

STANFORD SampleActivation Energy (eV) Trap Density (cm -3 ) Capture Cross-Section (cm 2 ) LM - GaInNAs x x x x x x x x MM - InGaAs x x x x Deep Level Transient Spectroscopy Majority Carrier Traps

STANFORD 1  m GaInNAs Film Transmission

STANFORD 2  m InGaAs Absorption Spectrum

STANFORD InGaAs vs. GaInNAs Dark I Density

STANFORD Dark and Photocurrent (SNR)

STANFORD Photovoltaic Response

STANFORD C-V Curves GaInNAs: 1/RC  7 MHz InGaAs: 1/RC  15 MHz

STANFORD LCR Resonant Circuit Modeling FWHM  15 MHz

STANFORD Damage Threshold Tests LIGO 1 power in each arm (W)ITM transmissionTotal Power on AS-PDSpot Radius (um)Area (cm2)Power Density (W/cm2) E E E E E E E E E E+06 AdLIGO power in each arm (W)ITM transmissionTotal Power on AS-PDSpot Radius (um)Area (cm2)Power Density (W/cm2) 8.30E E E E E E E+08