CecileT452RFDippingAt4K

First dipping of the device at 4K in the Heliox

Dipping Procedure

Check the level of Liquid Helium in the Fridge

- Open the dewar by turning the yellow part of 90 degrees

- Take the dipstick with the glove on top of it and dip it in the dewar

- When it vibrates, measure the distance between the top of the dipstick and the stop.

- Refer to the manual to find the level

- Note it on the Heliox dip sheet

Dipping

- Remove the clamp on top of it

- Remove the top of the dewar

- Insert the lower part of the dipstick

- Put the clamp back in place

- Tighten the screw to hold the dipstick

- Slowly lower the dipstick, the little needle should make a whole turn every 4 seconds minimum on the gas board.

Hall bar

2T Measurements

Use of the sensitive power supply : 100 micro Volts, 10 nA

4-6 : 1,5 nA

4-12 : 5,5 nA

4-13 : 5,5 nA

4-18 : 5 nA

4-16 : 0 nA

Remarks : Pin 16 Broken

4T Measurements

Use of the AC Lock-in Amplifier : 20 nA (2V through a 100MOhm transformer), 17 Hz of current excitation in Pin 4

13 - 16 : 80 (In) 2 (Out)

12 - 8 : 55 (In) 1 (Out)

12 - 13 : 0 (In) 0 (Out)

8 - 16 : -145 (In) 0 (Out)

All results in micro Volts.

IVg - Characterisitc

Use of 2 Lock-in amplifiers synchronized : 500 micro Volts (voltage attenuator) 17 Hz excitation

Resonance at 4K

Graphics at Vg = 0V, I = 11,1nA

Problem : the resonance didn't change with the gate voltage -> problem with the inductor ?

• As a general rule I would not forward bias a Schottky gate too much. For holes this means don't go negative.
• The other inidcator of a problem with the inductor is that the resonance frequency is very different to that measured previously.
  -- AlexHamilton - 26 Mar 2010

Tags

create new tag

Comments