The overall goal of the following experiments is to prepare anatomically defined templates for epit taxal growth of complex oxide thin films. The first approach to achieve this is chemical treatment of single crystalline strontium, titanate and DYS. Pros scan date substrates to obtain atomically smooth single terminated surfaces.
A second approach is to deposit a layer of nano sheets on arbitrary substrates by Lard Lodge or LB deposition to create a seed layer for subsequent film growth. The results show that epit Taxal films can be grown on the resulting templates as can be seen with atomic force microscopy and electron back scatter diffraction. When using persky oxide substrates, single surface termination is preferred to obtain high quality e architectural films.
The main advantage of using nano sheets over other existing methods is that relatively expensive and size limited single crystalline substrates can be replaced by virtually any substrate material. First immersed dispersion. Scan eight substrates in a beaker filled with acetone, and place it in an ultrasonic bath for 10 minutes After repeating this step with ethanol, use a nitrogen gun to dry the substrates by blowing the ethanol drops from the surface.
Check the surface of each substrate with an optical microscope. Remove any leftover particles by rubbing the substrate gently on an ethanol soaked lens tissue and dry the sample with a nitrogen gun. Repeat the previous steps until no particles are visible with the microscope anymore.
Next, aneel the substrates at 1000 degrees for four hours in an oxygen atmosphere. When finished, immerse the Ane spross scan eight substrates in a beaker containing deionized water using a Teflon holder. Then place the beaker in an ultrasonic bath for 30 minutes.
Transfer the Teflon holder carrying the substrates from the beaker with the deionized water to a beaker containing buffered hydrogen fluoride. After placing the beaker in an ultrasonic bath for 30 seconds, transfer the Teflon holder to a hydrogen fluoride resistant beaker containing deionized water and immersed for 20 seconds gently moving the holder up and down. Once the previous step has been repeated in two other beakers filled with water, leave the holder with substrates in a beaker containing ethanol.
Once all the buffered hydrogen fluoride containing liquid has been disposed dry the substrates using a nitrogen gun. Check the surface with an optical microscope repeating the cleaning step If dirt is visible. After filling a beaker with 12 molar sodium hydroxide, immerse the substrates using a Teflon holder and place the beaker in an ultrasonic bath for 30 minutes.
Following immersion in one molar sodium hydroxide, rinse the substrates by subsequent immersion in three beakers with water, and finally in a beaker with ethanol. Then dry the substrates using a nitrogen gun. Check the surface with an optical microscope and clean if necessary, using the procedure described previously following calcium ovate nano sheet preparation.
Clean the willy plate by rinsing with deionized water. Then clean the plate with oxygen plasma at high energy for at least three minutes for each side. Store the willy plate in deionized water immediately afterwards.
Next, clean the LB trough in the two barriers by rinsing with de ionized water and brushing with ethanol. After rinsing with de ionized water, again, dry the trough in two barriers with nitrogen gas, place a setup in a box that can be closed during deposition to protect against flowing air and dust and on an anti vibration table. Following this, remove 50 milliliters from the upper part of a fresh nano sheet dispersion with a syringe, and slowly add it to the trough while allowing the dispersion to rest.
For 15 minutes, clean an arbitrary substrate that is compatible with aqueous solutions. When finished, attach the substrate to the holder of the LB setup and give it a final blow. With nitrogen gas, place the holder in the LB setup.
Next, dip the willowy plate in the trough and carefully attach it to the spring. Remove droplets from the wire of the plate with a piece of paper. Lower the substrate until it touches the surface of the nano sheet dispersion.
Then set the height in the software to zero, lower the substrate further until the desired depth, making sure that the substrate holder does not touch the nana sheet dispersion. Following this, set the surface pressure in the software to zero and let the dispersion rest for 15 minutes. After setting the surface pressure in the software to zero again, start the first stage of the deposition by moving the barriers with a rate of three millimeters per minute to slowly compress the surface, monitor the development of surface pressure and surface area waiting until the increase of the pressure slows down significantly and the pressure approaches its maximum.
Enter the reached value as target pressure and set the dipper height to the actual value. Then start the second stage of the deposition by withdrawing the substrate from the dispersion with a rate of one millimeter per minute. Monitor the surface pressure.
Remove the willy plate when the deposition is finished after rinsing, store it in deionized water. Finally, remove the substrate after it has dried completely different terminations of anal dys. Pros, scandium oxide substrates can be seen as well as the morphology expected for single terminated substrates.
Higher surface roughness in both height and phase images compared to single terminated surfaces are an indication of the presence of both terminations. A kneeled in chemically treated strontium titanate substrates have well-defined terraces. Only unit cell height differences can be measured with atomic force microscopy indicating a single terminated surface.
The ultimate test for the success of a chemical treatment is the quality of the film groan on the substrate. Afterwards, strontium urinate grows well on single terminated substrates. Minor invisible regions of the second termination regions can have a dramatic influence on the film quality.
The surfaces of a monolayer of nano sheets are smooth, and the high differences with adjacent gaps approaches the crystallographic thickness of calcium ovate layers in their parent compound. Such monolayers allow for subsequent smooth film growth. A monolayer of nano sheets is fully oriented in the out of plane direction, but as a random, in plain orientation, due to the random in plain ordering of nano sheets, films grown on top are also textured.
In this video, you'll see two approaches to prepare anatomically defined templates for architectural growth of complex oxide, thin films. For both procedures, it's important to work clean and precise. Small contaminations can ruin the entire experiment.
