GaP cell on Echo
GaP cell was re-installed Fall 2024
GaP set points:
| GaP Base Temp | GaP Base Output | GaP Tip Temp | GaP Tip Output |
|---|---|---|---|---|
Idle (manual) | ~800 | 15.5 | ~658 | 0.0 |
Growth (manual) | ~1060-1070 | 22.8 | ~866 | 16.8 |
Outgas (manual) | ~1100 | 23.5 | ~900 | 19.3 |
GaP Base TC makes the sub TC go crazy, so I unplug the sub TC if I need to check the GaP Base Temp but for the most part I just assume that if the tip is stable, so is the base
Eurotherm PIDs have not been tuned for this cell yet.
Valve range: 0-200 mils in its current config
Notes on valve: Currently the valve faults pretty frequently when trying to open, my guess is that closing the shutter actually changes the temperature of the tip and results in it getting stuck, so during the wait time I tend to leave the shutter open, once its opening and closing for STOs it typically doesn’t get stuck but I am not sure how that’ll work during the junk growth where the close times are a little longer. I am going to tune the PIDs for the Tip and hopefully that should fix it, but I haven’t had a chance to.
Using the GaP cell to grow: Heating up the GaP cell destroys the background of the BFG, so I wait to heat it up until after I do my IIIs and As BEPs. Once I am done growing, I idle the cell and rehome the valve.
Ramping up cell (ex. From idle to growth):
! Manually open valve to ~ 80 first
eval GaP_OP = 15.5 repeat 73 eval GaP_OP = GaP_OP + 0.1 setparameter Output GaPBase=GaP_OP wait 00:00:30 er
eval GaP_OP = 0 repeat 168 eval GaP_OP = GaP_OP + 0.1 setparameter Output GaPTip=GaP_OP wait 00:00:10 er
open GaP |
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Ramping down cell (ex. From growth to idle):
! Valve opened to 90 and shutter already open
! set GaPTip setpt to 600C and ramped down in auto ! once at zero power put back in manual
! wait fot GaPTip to bottom out before running recipe waituntil (815 < GaPTip < 820) 10
eval GaP_OP = 22.8 repeat 73 eval GaP_OP = GaP_OP - 0.1 setparameter Output GaPBase=GaP_OP wait 00:00:30 er
waitop (once Tip and Base are stable rehome valve) |
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Last time I outgassed the cell:
Basically just ran an STO a few times since everything else had already been outgassed and we are pretty sure the cell is leaking
eval t_GaPValve = 180 eval t_GaPValve_Step = 10
open GaP ! calculate repeat 3 repeat 2 open Ga wait 20 close Ga wait 25 close GaP wait 2 eval mBG=bf t GaPValve = t_GaPValve wait 2 open GaP wait 40 eval mP=bf eval BEP = mP - mBG writefile (GaPFlux; t_GaPValve, mBG, mP, BEP) t GaPValve 0
er eval t_GaPValve = t_GaPValve + t_GaPValve_Step er |
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Outgassed the shutter by homing the valve and shuttering with long closed periods like we do in junk growth with Arsenic