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Entry  Mon Sep 23 10:49:27 2019, Koji, Summary, PD QE, QE and dark current of InAsSb sensors InAsSb_QE.pdfInAsSb_DarkCurrent.pdf190921_SbPD_QE.zip
    Reply  Wed Sep 25 01:05:30 2019, Koji, Summary, PD QE, QE and dark current of InAsSb sensors P_20190924_233507_vHDR_On.jpgP_20190925_003614_vHDR_On.jpgInAsSb_QE.pdfInAsSb_DarkCurrent.pdf
       Reply  Thu Dec 5 13:50:59 2019, Koji, Summary, PD QE, Dark current measurement with the sourcemeter InAsSb_DarkCurrent_markedup.pdf
Message ID: 2423     Entry time: Mon Sep 23 10:49:27 2019     Reply to this: 2425
Author: Koji 
Type: Summary 
Category: PD QE 
Subject: QE and dark current of InAsSb sensors 

The QE and dark current of all the InAsSb sensors were measured. All the measurements were done in room temperature.
- The incident beam power of the 2004nm beam was 0.95mW.
- The beam was focused down to 50um gaussian radius, which was confirmed by DataRay BeamR.
- The angle of incidence was ~0deg.

- The element side (nominally Pin 2, 3, or 6) were connected to the vias boltage (negative) and the common ground was connected to the transimpedance amplifier (Shalika OP140 R=5100Ohm)
- The dark current was highly dependent on the reverse bias voltage. The QE was also bias dependent.
- Sb3512 A2 have different behavior compared to others. Alex mentioned that Sb3512 is the test batch. We can exclude this sensor from the test.
- The best QE was ~0.7 for Sb3513 A3 P2 (Pink) and Sb3513 A2 P6 (Purple). Both have the area of 500um^2. These two particular elements have low dark current of <1mA. The dark noise of this specific sensor should be measured.

Some issues of the measurements

- The transimpedance amp (TIA) has suspicious behavior. The saturation voltage was ~17V rather than <-15V. This indicates that the voltage regulators possibly have leakage of the input voltage (+/-18V) to the output line. This needs to be checked, particularly before the dark noise test.

- TIA saturation: The bias voltages could not be raised to ~1V for some PDs because of the dark noise and the saturation of the TIA. The transimpedance should be lowered by a factor of ~5.
- Because of the low bias voltages of these saturated cases, the max QEs were not reached. This also prevented from checking if there was any clipping loss. This should be checked again with the lower transimpedance.

- TBD: The angular dependence and the reflectivity of the sensor should be checked. It is difficult to carry out these tests without a sensor card.

Attachment 1: InAsSb_QE.pdf  138 kB  Uploaded Tue Sep 24 23:22:24 2019  | Hide | Hide all
Attachment 2: InAsSb_DarkCurrent.pdf  138 kB  Uploaded Tue Sep 24 23:22:31 2019  | Hide | Hide all
Attachment 3: 190921_SbPD_QE.zip  693 kB  Uploaded Tue Sep 24 23:22:38 2019
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