How to View (100), (110) and (111) Atomic Planes in Silicon with Crystal Viewer 3.0 1. Log in to nanoHUB or create a free nanoHUB account at https://nanohub.org/register. ​ ​ ​ ​ 2. Go to Crystal Viewer on nanoHUB.org ( https://nanohub.org/tools/crystal_viewer/ ) and click the ​ ​ ​ ​ Launch Tool button . ​ 3. Click the Settings button in the lower right corner . ​ ​ Instructions for viewing the silicon crystal structure 4. Silicon is set up as the default structure, so you do not have to change any of the input parameters. The details are: a. I want to… view a material ​ b. Choose a crystal structure: Diamond ​ c. Material: Si ​ d. m=n=p=2; these numbers tell how many times to repeat the basis in each direction. ​ ​ This is also a good time to study the structure details shown: We will be using the conventional unit cell, which has Bravais vectors a1, a2, and a3 along the x, y, and z directions. Silicon is a cubic crystal, so a1=a2=a3= 0.5431nm. This is the repeat distance for the ​ ​ standard cubic unit cell. This number will be used later to set up the position of the planes cutting through the silicon structure in the next section, so write it down. 5. Click the Simulate button in the lower right corner . ​ ​ The first view you get is the “Textbook Unit Cell”, which you can rotate and zoom into. The blue, green and purple balls mark the ends of the x, y, and z axes. This work by Tanya Faltens, 2017, is Licensed under Creative Commons 3.0 CC-BY-NC-SA updated 7/26/2020 The default view of the “Text book unit cell” for the diamond cubic structure. In the Result drop-down menu, select Lattice Grid. Use the controls (show by icons) in the right-hand ​ ​ ​ ​ ​ menu to adjust the view. - Molecule Settings - Show Outline to view the simulation cube - Select the Molecule Representation. Ball and Stick or Spheres are popular choices. ​ ​ ​ ​ - Adjust the Atom scale to see a space-filling representation (bonded atoms touch). - Increase the Quality to around 6 - Axis Settings - Click to hide the axes - - Camera Settings - Turn orthographic view on or off - Click one of the 6 view cubes across the top to align the structure along designated directions. 6. To save the image, click the green download arrow , select Image File, then Save . ​ ​ ​ ​ ​ ​ ​ This work by Tanya Faltens, 2017, is Licensed under Creative Commons 3.0 CC-BY-NC-SA updated 7/26/2020 Example of downloaded Si 2x2x2 structure, looking down one of the principal axes. Instructions for viewing the (110) plane in silicon 1. Click the Settings button to go back to add the cut plane. ​ ​ 2. Scroll to the bottom of the page and toggle the Draw Miller Plane switch to say yes. This will ​ ​ ​ ​ open up more options. 3. Scroll down and set h = 1, k = 1, l = 0 for the (110) plane. ​ ​ 4. Toggle the Manually set plane 1 intersection point switch to say yes. This will open up more ​ ​ ​ ​ options. 5. Scroll down and select an axis for the cross point. In order to place this plane diagonally across the center of the unit cell, set its intersection point to be on the x-axis or on the y-axis, crossing at a distance of one unit cell parameter (0.5431 nm) because there is an atom there. Note that this ​ ​ plane is parallel to the z-axis, so has no intersection there. Set the distance for the x axis cross point. This work by Tanya Faltens, 2017, is Licensed under Creative Commons 3.0 CC-BY-NC-SA updated 7/26/2020 6. Click the Simulate button in the lower right corner . ​ ​ 7. In the Result drop-down menu, select Crystal on one side of plane 1. You will see a green ​ ​ ​ ​ plane cutting through the structure, and all of the atoms on one side of the plane are removed. 8. Adjust the atom size and quality, and camera view angle as you like, and download an image. These figures show views of the (110) plane in Si with a space-filling representation of atoms, looking at the xz plane, and looking down the [110] direction, perpendicular to the cut plane. Perspective view down the y-axis at Orthographic view down the [110] the (110) plane in Si direction at the (110) plane in Si Instructions for adding views of the (100) and (111) planes in silicon 1. Click the Settings button to go back to add two more cut planes. ​ ​ 2. Set up Plane 2 and Plane 3. You can change the location of the cut plane to cut through more atoms, rather than cutting through a smaller cross section of the simulated crystal. You can optionally challenge your students to do some geometrical calculations to determine the best cross points for these planes. Input values for the (100) plane Input values for the (111) plane This work by Tanya Faltens, 2017, is Licensed under Creative Commons 3.0 CC-BY-NC-SA updated 7/26/2020 Following are views of the (100), (110) and (111) planes in Silicon. These views allow a visual comparison of the atom densities on these three planes, which can affect the oxidation rates of different orientations of silicon wafer. The different symmetries can also be observed. Si (100) plane Change the parameters to view a larger sample Si (110) plane Change the parameters to view a larger sample Si (111) plane Change the parameters to view a larger sample This work by Tanya Faltens, 2017, is Licensed under Creative Commons 3.0 CC-BY-NC-SA updated 7/26/2020 .