Disassembling the STM

1. Open acoustic box
2. Disconnect the 2 main connectors (plug and coax cable) on STM (Figure 1)


Figure 1. Connectors.

3. Take STM unit our of acoustic box (Figure 2)
 

Figure 2. STM unit and Acoustic box.

4. Loosen course positioning screws (2) until sample holder is free. (figure 3)

• Knob A twists counter clockwise to loosen
• Knob B twists clock wise to loosen

Figure 3. Positioning Knobs.

1. Remove sample holder from STM Module (Figure 4)

• Careful not to damage the tip

Figure 4. Sample holder.

Cleaning Sample

1. Supplies needed Scotch Tape.

2. Take a strip of tape and firmly press onto the sample on the sample holder
1. Carefully remove the tape

• While removing the tape you want a continuos layer of the sample material to come off onto the tape.
• Sometimes this does not occur and jagged flecks of the sample material are left on the sample surface. These need to be removed with the tape
• This is done by touching the tape to the sample until those areas are smooth and one even lay of the sample is exposed

1. Remove the Sample plate
2. Remove the tip from the tip holder (Figure 5)

• Use large magnifying glass with back lighting
• Use needle fine tipped pliers to grip the tip

Figure 5. Tungsten Tip.

1. Select a new tip
2. Using fine tipped pliers pace ¼ of the tip into the tip holder
3. Slightly bend the tip to one side of the holder
4. Press the another ¼ of the tip into the holder
5. Slightly bend the tip in the opposite direction of step 5
6. Press the tip the rest of the way into the holder.

• Note: This is done to hold the tip firmly in place.

1. Carefully place sample holder plate into STM module (Figure 6)

• Sample facing the tip

Figure 6. Assembled STM Unit.

1. Using the 2 course adjusting screws roughly adjust the sample holder to obtain a flat sample plain (See Figure 3)

• Turn Knob A clockwise to tighten
• Turn Knob B counterclockwise to tighten

1. Use a light microscope to due fine adjusting of the tip close to the sample surface

• CAUTION: Do not touch the tip to the sample. This will ruin the tip

• Use the mirror image scene on the sample and the real image of the tip as a guide to how close the tip is to the surface

• Careful not to touch the surface with the tip. This will ruin the tip

Figure 7. Light Microscope.

4. Place the STM module back into the acoustic box on the dampening unit (Figure 8)


Figure 8. Dampening Unit.

1. Reattach the 2 main connectors (plug and coax cable)

1. Turn on computer
2. Make sure the Isolation Power supply is hooked up to power the STM (Figure 9)

• NOTE: If the Isolation power supply is not hooked up the image received by the computer will be contaminated with noise for the standard power socket

Figure 9. Isolation Power Supply.

1. Turn on the CSTM 9000 Unit I, power switch located on back of unit (Figure 10)

Figure 10. CSTM 9000 Unit.

• V_bias = approximately 35 mv (Figure 11)
• I_ref = approximately -0.99 nA (Figure 11)

Figure 11. V_bias, I_ref, Z_voltage.

2. Turn on High Voltage Unit IV, a large red toggle switch (Figure 12)

• Z_voltage >+140 volts

Figure 12. High Voltage Toggle.

Setting up Computer Program

• NOTE: CNTL C will terminate the program at any time

1. Locate VSCAN1.EXE on the computer
2. Change directories to C:\STM to Find VSCAN1
3. Run this program by typing VSCAN1 at prompt. C:\STM\VSCAN1
4. Press <ENTER>
5. Main Menu will appear with options (Figure 13)

• Title Acquisition Program
• Quite to Menu -- Exits to main menu
• Option Topo -- Topographical scan
• Sts scan -- Do not use this function, (not operational)
• Iv curve -- Do not use this function, (not operational)
• Move Tip -- Moves the tip
• Change Para -- Do not use this function, (not operational)
• File Para -- Do not use this function, (not operational)
• Engrave -- Will make a trench in the sample with the tip

Fine Adjustments of the STM

1. Use the 2 course adjustment screws to move the tip close to the sample

• CAUTION: This is a very sensitive procedure

• Watch the Z_voltage as this is done
• Turn Knob B counter clockwise very slowly to make the necessary adjustments
• As Z_voltage approaches zero volts stop the adjustment
• The working range for the Z_voltage = 15 – 0 volts

2. Reseal the acoustic box
3. Let system settle out vibrations for approximately 5 minutes.

1. Select T this will start the computer scanning the sample
2. The computer screen will automatically change and start to display the sample scans
3. ESC to return to the main menu

1. To change the scanning method flip the output switch on the CSTM-9000 unit (Figure 13)

Figure 13. Scanning Method Switch.

• CC – Constant Current Scan
• CH – Constant Height Scan

1. Quite VSCAN1 program
2. Open up Acoustic box and back the tip away from the sample surface

• Use Knob B and turn it clockwise
• Adjust the tip until Z_voltage = > +140

1. Turn off the High Voltage switch on the CSTM-9000
2. Turn off unit I (Power switch is on back of unit)