SEM-EDS Protocol V1

Protocol SEM/EDS 1.1 Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analysis Saylen Sofia Paz, David Bahamon-Pinzon, Diana Vanegas Gamboa Clemson University This protocol describes the process of performing the Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analysis of laser-inscribed graphene (LIG) electrodes (e.g. Protocol L-Cu1.1) using a Scanning Electron Microscope SU5000. Fig 1 depicts the process for the analysis. The time must be change according with the number of the samples that you have.

MATERIALS

• LIG sensors (Protocol L-Cu1.1)
• Tweezers
• Tape. NEM. Nisshin em.co.ltd
• Sampleholder
• USB

HARDWARE

• Scanning Electron Microscope SU5000.

Step 1) Turn on the computer and equipment screens

• Login from any device with internet access to iLab's website (iLabFacilityScheduling (clemson.edu))
• Log into your account
• Click on the start button Note: Automatically, the screens of the equipment will turn on (Figure 2)

Step 2) Preparation of the sample

• Take a piece of carbon tape and put it in a 51 mm holder
• Remove the layer that is covering the tape
• Place the samples over the tape using the tweezers (Fig 3A)
• Put the bottom part of the holder (Fig 3B)
• Verify that the height of the holder and the sample is within the range of the scale (Fig 3C) Note: Try to organize the samples with something that you can recognize each sample

Step 3) Set up the equipment

• The equipment is always under high vacuum. Letting air in the equipment is necessary to open the chamber and place the sample. To do this, click Air in the Specimen/vacuum setting (Figure 4)
• The equipment should start beeping. Wait for the process to be completed. It beeps three times
• Click Specimen settings in the popup window (See Figure 4)

3.1 Select stub and Height Adjustment

• Select the diameter of the holder or stub (51 mm)
• Click Next
• Choose the height of the holder, including the sample
• Click Next (See Figure 5)

3.2 CameraNavi setting (optional)

• Turn the light of the camera on with the switch
• Put the holder on the camera. The holder must reach the top (Fig 3)
• Click movie
• Push the buttons to zoom in or out
• Click capture
• The holder should fit the circle in the screen. Move with the mouse.
• The triangle and circle in the screen should fit the holder
• Click set
• Green should show up
• Click next (Figure 6)

3.3 Placeholder in the chamber

• Pull the gate of the chamber all the way out until you hear a switch (Fig 7)

• Click stage move Note: It starts beeping as it moves up the stage

• When it stops beeping, put a sample. The holder must reach the top. The top is gate located next to the wall of the room

• Close the chamber slowly and verify the height of the holder. The sample should be under the plate

• If the sample is too tall, pull the equipment out again until you hear the click and click down as needed.

• Close the door entirely until hearing a slight beep.

• Click Next (See Figure 7)

3.4 Evacuation

• Choose Conductive or non-conductive samples
• Choose High or Low vacuum
• Click Evac
• It says Pumping in the current vacuum
• The line from the central cross indicates the direction of the sample (Figure 8)

Step 4) Set settings for SEM

• Set the following parameters in “Electron beam”: o Accelerate voltage: 5 – 15 kV (for imaging).

o Imaging: any value

o Light elm

o Spot int: 40. Scale 0-100. This is the current

• Click start (See Figure 9)

Step 5) Insert detector

• Verify that Detector BSE-All is selected in the top right
• Check that BSE can load in the field specimen
• BSE (Back-scattered Electron Detector) able to load
• Insert the detector by turning slowly in the “IN” direction until it stops (Figure 10)
• Click OK in the pop-up window

Step 6)Calibrate the beam (brightness, contrast, focus)

Note: There are several parameters that can be adjusted from the box of the equipment

• Brightturn knob inc

• Contrast

• Speeds o 1. Fast, 2. Slow, 3. Red (reduced). Click 2 twice to change to 2.1.

• Focus

• Coarse

• Stigma(stism)

• Click mode to change to alignment

• Loo for something to focus

• When finding something, click 1. Bum aligment

• Center beam by adjusting X and Y knobs

• If nothing happens when clicking auto bright, check alignment

• Click mode

• Set an appropriate picture for alignment. The focus should not move after this

• Aperture alignment

• Moving alignment

• Move x. Then it doesn’t move.

• Click mode

• Stigma alignment for X

• Click mode. I f it looks fine, push mode again. Note: Always focus at high magnification (e.g. more than 25X)

• VP: low vacuum (vacuum pressure)

• 60 Pa

• Click start

Step 7) Set capture settings

• Go to capture settings in the bottom right corner of the screen

• Save settings Select the folder "Vanegas" Note: If is necessary, create the folder

• Click to capture settings

• In capture settings, select: o Speed: slow

o Image size: 1280x960 (adequate for papers, not

for posters or magazines. For posters, use 5120x3840)

o Time: 16 s. This corresponds approximately to Slow 3

Step 8) Take picture

• In the box, press Capt to capture pictures. Note: After each capture, the software changes to Freeze. Press 4  in the box of commands to return to Run.

Step 9) Set settings for EDS

• Change voltage to 15 kV. 5 kV is proper for carbon but not for platinum or copper. Note: The working distance should be 10 mm. For example, If the distance in the screen is 6.2 mm, we need 4 mm more. We need to add 4 mm to the value of Z (in

Specimen/Vacuum settings). If Z was 5 at the beginning, set a Z of 9.

• 7.4-10=2.5

Step 10) Open the software for EDS

• In the second screen, open the software Aztec. Open project LIG (create a new folder or  select the folder “Vanegas”)

• Process time: 6. Note: The process time of 1 is the slowest, and 6 is the highest.

• Element distribution

Step 11) Final parameters and start

• Verify that the dead time is around 40%
• Select EDS-SEM in the top left area of the screen.
• Set Analyze: overall.
• Select Point 81D (scan specific position). Other options include color map, line graph
• Click New specimen
• Click New sample
• Uncheck box Specimen is coated
• Click Scan image
• Click Settings
• Select a Scan size of 1024
• Dwell t (time/pixel): 5 μs
• In the “sun” at the bottom right corner, the brightness can be adjusted
• Click Start

Step 12) Remove the sample from the chamber

• When the analysis is completed, click “Stop”
• Take the detector out by tunning the knob in the “OUT” direction until it stops.
• In Vacuum, select Air.
• Click Finish
• Pull the gate of the chamber to open the equipment.
• Take the sample holder out.
• Close the chamber.
• Click “Evac” (the equipment must remain in High vacuum when not used).
• Clean the working station

"dark"areas have lower average atomic number* Detectors: o BSE is used to find differences in composition. High energy elements.

o Secondary electrons (SE) has lower energy. It is used to study the sample surface and texture (this detector didn’t work well because of the substrate for LIG samples)

• A higher pressure from a low vacuum setting will scatter the electrons, and the image will be distorted
• For EDS, 5 kV is adequate for Carbon but not for copper or platinum
• For elements such copper, platinum and gold an adequate potential ranges 15 – 20 kV
• For LIG samples, it is adequate to work in non-conductive samples and low vacuum
• For high resolution images, it is recommended to use the autofocus and auto contrast from the program and slow 3