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======= Resistance evaporator manual ======
====== Description ======
The resistance evaporator is configured for evaporating 3 different materials with a chamber background pressure off ~5e-8mbar. \\
It is equipped with a crystal thickness monitor below the shutter to set stable conditions, monitor deposition rate during the process and determine total evaporated thickness. \\
The sampleholder is loaded via a turbo pumped loadlock.


====== Checking materials and boats =====
Before loading a sample it is good practice to check if there is material present in the boat and the boats are intact.
You cannot check if there is still Cr on the rod, but typically Au runs out before Cr.

  * Check with the multimeter all boats you wish to use, resistance should be ~150mOhm
  * Check the logbook and see how much material is evaporated since the last maintenance, a full boat should last ~400nm in total.
  * Apply a low voltage to the boat you want to use, the voltage should be high enough to create some heat radiation, but low enough to avoid evaporation. With the heat radiation you should be able to see if there is still material in the boat.

====== DO's and DONT's ======
  * Touch vacuum parts only with //powderfree gloves//
  * The vacuum control is not protected. Be careful to operate the roughing valves in the correct way!\\ Opening a roughing valve to a vented chamber while the other valve is open will cause irrepairable damage!
  * Do not hot switch the selector, this will burn the relay contacts! (switching while a voltage is applied)
  * Do not wait after obtaining a stable evaporation rate for Au, it wastes material
  * Be very careful not to make a short when switching over the multimeter
  * Heat up and cool down the material slowly, take at least two minutes to ramp up and ramp down.


==== Loading the sample ====
  * Write name, date, sample, materials & thicknesses in the logbook
  * Check that the system is in the standby state with chamber and loadlock pumping
  * Switch off loadlock ion gauge
  * Close loadlock roughing valve
  * Switch off loadlock turbo
  * Let in a very small amount of nitrogen via the vent knob to decelerate the turbo
  * When turbo is below 50Hzv completely vent the loadlock, then close the vent knob
  * Remove the sample holder, be carefull and try to avoid touching/scraping the bellow
  * Mount the sample with the springs
  * Load the sample holder
  * Close chamber roughing valve, do not leave the system >5 minutes in this state
  * Open loadlock roughing valve slowly
  * When p< 5mbar, switch on loadlock turbo
  * When p<5e-2 mbar at the pre-pump, open chamber roughing valve (keep an eye on the chamber pressure)
  * Wait till loadlock turbo is at speed with standby current, 1500Hz and ~0.3A
  * Turn on loadlock ion gauge (this will considerably speed up pumping times)
  * Sample can be transfered when loadlock pressure <1e-6mbar, this typically takes 2hours.

==== Lowering sample ====
  * Check that loadlock pressures <1e-6, open the gate valve (pen in = closed, pen out = open)
  * turn bellows to 0 mm (but not further!)

==== Repeat for each layer ====
  * Wire multimeter to correct connection
  * Verify the shutter is closed
  * turn on crystal monitor and set tooling factor to 21%
  * Set the density and Z-ratio for the desired material
  * Switch switchbox to the correct boat/rod
  * Switch on all 3 power supplies
  * Heat slowly (in 3 min) till the desired rate is reached
  * Open shutter, zero XTC
  * When desired thickness reached, close shutter
  * decrease voltage by 0.5V to stop deposition
  * slowly reduce voltage to OV (3min), turn off supplies

==== Stopping the system ====
  * Boat selector to Off
  * Turn bellows up to 150 mm
  * Close gate valve
  * Crystal monitor off

==== Removing the sample ====
  * Switch off loadlock ion gauge
  * Close loadlock roughing valve
  * Switch off loadlock turbo
  * Let in a very small amount of nitrogen via the vent knob to decelerate the turbo
  * When turbo is below 50Hzv completely vent the loadlock, then close the vent knob
  * Remove the sample holder, be carefull and try to avoid touching/scraping the bellow
  * Remove sample
  * Load the sample holder
  * Close chamber roughing valve, do not leave the system >5 minutes in this state
  * Open loadlock roughing valve slowly
  * When p< 5mbar, switch on loadlock turbo
  * When p<5e-2 mbar at the pre-pump, open chamber roughing valve (keep an eye on the chamber pressure)
  * Wait till loadlock turbo is at speed with standby current, 1500Hz and ~0.3A
  * Turn on loadlock ion gauge (this will considerably speed up pumping times)


====== Maintenance and loading materials =====

  * 4 grams Au in the boats, write down exact amount in logbook
  * replace Cr rod
  * check crystal lifetime, if >30 replace crystal
  * clean/check mirror
  * clean o-ring
  * measure resistances of boats (should be ~200mOhm) before pumping


====== Sample holder chiller ======

==== Flashing display ====
An uncontrollable chiller with a flashing display means that there is a firmware bug. The first fix to try is:
  * Switch off chiller
  * Press and hold down the rotating knob
  * Switch on chiller
  * Release knob

This should start up the chiller again with normal functionality.
If the problem still persists try to install (overwrite) the firmware by following this manual: {{:equiment:tlc10-firmwarefix.zip|}}


====== Recipe for flat Au films on Mica ======
This recipe is used for making flat epitaxial Au films on mica in the resistance evaporator by using the heated sample holder. It consists of a copper heating block with a thermocouple placed inside and the copper wires sticking out from the sample holder are connected to the power source, and the steel wires are connected to the voltage meter (that measures temperature based on thermocouple measurements). The calibration list is given on near the log book.

==== The steps ====
  * Cut mica sheet to your required sample size with mica cutter
  * Mount on the mica sample on the copper heating block with the fleshly cleaved side up
  * Install the cover on the sample holder
  * Install the sample holder in the system and pump down (see above) to < 3.5E-7 mbar
  * Heat the sample to 500 °C for 6-12 hours
  * Decrease the temperature to 350 °C (it might also work 330-375 °C)
  * Increase the deposition rate to >0.3 nm/s with the shutter closed for several minutes
  * Set the rate to 0.3 nm/s, open shutter and start deposition
  * Close shutter when 100 nm Au is deposited
  * Anneal for 1 hour at 350 °C
  * Cool the sample holder by venting the system with N<sub>2</sub> (see above)


[[Technicians:Technical UHV resistance evaporator|Technicians]]