Laser Testing of 3D Sensors

1
Laser Testing of 3D Sensors

• Martin Hoeferkamp, Sally Seidel, Igor Gorelov
• University of New Mexico
• 13 Feb 2006

2
Introduction

• Framework to assist ATLAS in selecting a
  technology for pixel sensors in the upgrade era.
• Specifically to characterize 3D sensors for the
  U.S. ATLAS Upgrade group (Sherwood Parker).
• Previous Activities/Measurements (2004-2005)
• Received non-irradiated and irradiated (1014 ,
  2x1014 , 1015 cm-2 55 MeV p)
• 3D sensors from Sherwood Parker.
• Measured
• Leakage Current (IV measurements)
• Depletion Voltage (CV measurements)
• Capacitance (LCR meter)
• Recent Laser Measurements (2006)
• Signal Collection
• Depletion Voltage
• Position Scans

3
3D Sensor Configuration

• Configuration of Measured Devices

• Top view layout

• Layout dimensions

4
Test Setup
Fast Pulser
Oscilloscope
Laser
PICOPROBE 35
Vbias
R 1.25M
C.05pF
Thermal Chuck

• Laser 1064 nm
• Probe Picoprobe 35, 26 GHz, Cascade Microtech
  coaxial
• Oscilloscope Tektronix TDS7254, 2.5 Ghz BW
• Thermal Chuck Micromanipulator (-60oC )

5
Voltage Scan

• To test the entire device completely flood the 3D
  sensor with a uniform laser spot and scan the
  Bias Voltage above full depletion.
• Photo with IR filter of laser illuminating the
  sensor

6
Voltage Scan (preliminary)

• Oscilloscope traces of laser induced signals on n
  and p electrodes

7
Voltage Scan Results (preliminary)

• Very Preliminary

8
Voltage Scan Results (preliminary)

• Very Preliminary
• P-electrode efficiency varies linearly with
  fluence, N-electrode does not
• Depletion voltage is very low for all fluences

9
Laser Position Scan

• Scan the laser across one electrode cell to
  measure uniformity of signal collection
• Laser is focused to 10 mm spot diameter

Pulsed1064nm IR Laser
Vbias
Gnd
PICOPROBE 35
To Oscilloscope
R 1.25M
C.05pF
10
Laser Position Scan

• Scan the laser across one electrode cell to
  measure uniformity of signal collection

Y
X
11
Position Scan, n-electrode

• Very Preliminary
• Non-Irradiated 3D sensor

Y
X
12
Position Scan, p-electrode

• Very Preliminary
• NON-Irradiated 3D Sensor

Y
X
13
Charge Collection (prelim)

• Pulse the IR Laser as fast as possible and
  observe the rise time of the signal

• Measure the output rise time while decreasing the
  laser pulse duration

14
Charge Collection (prelim)

• Example 4.1 nS laser duration, 5.5 nS output
  rise time

• Output Unirradiated P Electrode

• Input laser pulse width

15
Charge Collection (prelim)

• Input 1.5 nS laser duration, 3.5 nS rise time

• Input laser pulse width

• Output Non-irradiated P Electrode

16
Charge Collection (prelim)

• Input 0.3 nS laser duration, 2 nS rise time

• Output Non-irradiated Pelectrode

17
Charge Collection (prelim)

• Input 0.3 nS laser pulse duration, 2 nS output
  rise time

• Output Irradiated P Electrode

• Output Irradiated P Electrode

18
Summary of Laser Studies

• Depletion Voltage is very low (120V for sensor
  Irradiated to 1015 cm-2 55MeVp)
• Charge Collection Time is very fast ( 2 nS for
  sensor Irradiated to 1015 cm-2 55MeVp)
• Performance of 3D Sensor is Very Impressive

• Present Work,
• Laser Position measurements on irradiated sensors
• Developing capture time measurements