Pin controls

• Pins are used to supply the HV, ground the guard ring and connect the sensor pad, as shown in the left image below.
• The pins are connected as follows (as illustrated in the lower right schematic):
  • the pin closest to the cabinet door is to ground the guard ring,
  • the middle pin provides the HV to the chuck,
  • the further pin is to measure the current through the sensor pad.

• To position the pins on the pad or guard ring is tricky. Look through the microscope and use the small knobs on the needle mounts.
  • The function of each of these knobs is shown in the schematic below:

Instructions for measurements

The HGTDSensors twiki contains instructions/recommendations for making sensor tests. Currently we're keeping the CERN team measurements in this spreadsheet.

To set up the PC for IV or CV measurements:

• Switch on computer, booting up Windows
• Load up labview project:
  • Documents → Labview project → cviv-daq → CVIV
  • Select CV-IV-control.vi from the list of options displayed in LLB Manager
  • When the CV-IV-control.vi project opens, click on the , button on the menu bar
    • This takes you from edit mode to running mode
• Fill out the relevant fields in the labview GUI according to the measurements you wish to make (see following sections).

IV (floating guard ring)

Labview settings

Parameter	Setting	Comment
Integration time	3 [20 ms]
Drop down menu to right of "Device name"	pFZ	Default assuming non-irradiated sensors.
Number of steps	Calculate (2V)	e.g. Start: 0, Stop: -100, Number of steps: 50
Tester
Start	0 V
Step mode	linear
Averaging (count)	3	Number of measurements taken at a single voltage point for averaging.
GPIB	21	Port for Keithley 2410
Type of measurement	IV	Select from drop-down menu.
Compliance.	1e-6 A	Sensor dependent (have seen nA currents for HPK Type 1)
Compl. Stop	ON	This ensures that the measurement cycle will cease, and the voltage ramp down, should the sensor reach the compliance you set.
Stop	-100 V	This is the max voltage for the scan (will differ between sensors). Note that the value must be negative.
Device name	Sensor name	Usually this should be the name written on the sensor packaging. This will be the name of the folder in which the results will be stored.

IV (grounded guard ring)

Connecting the sensor

• Ensuring the voltage source is off, open the probe station cabinet and switch on the light.
  • The light switch is located in the back left-hand corner of the cabinet.
• Turn on the vacuum pump.
  • Turbulence from the pump the instant it is switched on will cause the sensor to move violently if you try to turn on the pump after placing the sensor!
• Using plastic tweezers, gently place the sensor onto the chuck, positioning it over the small hole in the centre.
  • The sensor should completely cover the hole so that the vacuum is effective.
• Position the needles on the sensor, as shown below.

• Switch off the light and close the cabinet doors.

Labview settings

Analysis of IV/CV data:

• Data is stored in Documents → Labview project → cviv-daq → CVIV folder
• Code to make IV plots from the raw data can be found here: https://gitlab.cern.ch/CERNHGTD/ivlabview

Useful links

• HGTDSensors twiki

• CERN HGTD team gitlab area

-- EmmaKuwertz - 2019-05-21