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Scripts, Tutorials and Applications / Re: Thermionic vs Tunneling Based on Spectral Current for P-Type Semiconductor/Metal
« on: June 14, 2025, 02:43 »
Ok, thank you for the help!
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Scripts, Tutorials and Applications / Re: Thermionic vs Tunneling Based on Spectral Current for P-Type Semiconductor/Metal
« on: June 7, 2025, 02:19 »
Thank you for the response. Given that the "lower energies" would indicate a more negative energy to overcome the downward (negative) Schottky barrier height in the case of thermionic emission, I think it would make more sense to plot the data without the absolute values as shown in the attached image (updated_spectral_current_plot.png). Please correct me if I am wrong in the newly plotted interpretation.
My question stemmed from seeing how the Spectral Current tab from the Transmission analyzer shows the spectral current above the Fermi level E_f at an energy of around +0.7 eV for the "positive" (left-to-right) current as shown in the next attached image (atk_spectral_current_-0p25_V.png). I would have expected the spectral current to appear below E_f at -0.7 eV, thinking that the "positive" current from the holes that are flowing would be from the valence band (which is below E_f). Would it not be correct to plot the spectral current below E_f as I am now doing, rather than how QuantumATK does it by default?
My question stemmed from seeing how the Spectral Current tab from the Transmission analyzer shows the spectral current above the Fermi level E_f at an energy of around +0.7 eV for the "positive" (left-to-right) current as shown in the next attached image (atk_spectral_current_-0p25_V.png). I would have expected the spectral current to appear below E_f at -0.7 eV, thinking that the "positive" current from the holes that are flowing would be from the valence band (which is below E_f). Would it not be correct to plot the spectral current below E_f as I am now doing, rather than how QuantumATK does it by default?
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Scripts, Tutorials and Applications / Thermionic vs Tunneling Based on Spectral Current for P-Type Semiconductor/Metal
« on: June 1, 2025, 22:03 »
Hello QuantumATK Representative,
I have a question that stems from the "Modeling metal–semiconductor contacts: The Ag–Si interface" tutorial as well as the paper from D. Stradi et al. (Phys. Rev. B, 93:155302, Apr 2016). I will keep the question as general as possible when referencing my current model so that it is applicable to other similar systems and QuantumATK users.
I am currently modeling a two-probe semiconductor-metal system with the semiconductor layer being classified as a p-type semiconductor material, not n-type as in the tutorial. After calculating the Transmission Spectra at different bias conditions, I obtain the spectral current and plot it along with the Schottky barrier height determined from the p-type semiconductor-metal PLDOS analysis. My question is if one is dealing with a Schottky barrier that is pointing downward (i.e. band bending downward to create a barrier for holes coming from the p-type semiconductor layer to the metal contact), is the thermionic and tunneling mechanism classification still the same as in the tutorial (where above the Schottky barrier value line is thermionic emission and below the line is tunneling)? I have attached an image in an effort to show how I am plotting the HDP with respect to the valence band of the semiconductor and the right chemical potential mu_R in the metal contact as well as the spectral current with respect to mu_R. I have used absolute values for the E - mu_R y-axis and phi^pot value since I was unsure if I should specify them as negative values when defining a spectral current for a p-type semiconductor-metal. Please let me know if any other additional details are needed and thank you in advance.
I have a question that stems from the "Modeling metal–semiconductor contacts: The Ag–Si interface" tutorial as well as the paper from D. Stradi et al. (Phys. Rev. B, 93:155302, Apr 2016). I will keep the question as general as possible when referencing my current model so that it is applicable to other similar systems and QuantumATK users.
I am currently modeling a two-probe semiconductor-metal system with the semiconductor layer being classified as a p-type semiconductor material, not n-type as in the tutorial. After calculating the Transmission Spectra at different bias conditions, I obtain the spectral current and plot it along with the Schottky barrier height determined from the p-type semiconductor-metal PLDOS analysis. My question is if one is dealing with a Schottky barrier that is pointing downward (i.e. band bending downward to create a barrier for holes coming from the p-type semiconductor layer to the metal contact), is the thermionic and tunneling mechanism classification still the same as in the tutorial (where above the Schottky barrier value line is thermionic emission and below the line is tunneling)? I have attached an image in an effort to show how I am plotting the HDP with respect to the valence band of the semiconductor and the right chemical potential mu_R in the metal contact as well as the spectral current with respect to mu_R. I have used absolute values for the E - mu_R y-axis and phi^pot value since I was unsure if I should specify them as negative values when defining a spectral current for a p-type semiconductor-metal. Please let me know if any other additional details are needed and thank you in advance.
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Scripts, Tutorials and Applications / Re: Zn-ZnO-Zn Transport Calculation
« on: January 27, 2023, 05:12 »
It's probably too long a period of time since there was any response to your post, but I thought I would give it a try. According to the previous forum post you are referencing, the selection of the "smallest atoms possible" is referring to the interface builder window with all calculated in-plane strains depending on whether the first layer, second layer, or both layers are strained. You want to select the dot on the lower panel that gives the lowest number of atoms while still minimizing the amount of in-plane strain resulting between the first and second layers.
The "repeat a bit on both sides of the interface" part would mean to add additional atomic layers to both sides of the interface using the "+" buttons you see under each displayed bulk material within the interface builder pulldown menu. Additional layers for each bulk material that are joined together to form the interface will be included in the supercell slab model. There are other ways to add more layers to both sides of the interface, but I will leave that out of the discussion for now. I hope that helps some.
The "repeat a bit on both sides of the interface" part would mean to add additional atomic layers to both sides of the interface using the "+" buttons you see under each displayed bulk material within the interface builder pulldown menu. Additional layers for each bulk material that are joined together to form the interface will be included in the supercell slab model. There are other ways to add more layers to both sides of the interface, but I will leave that out of the discussion for now. I hope that helps some.
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General Questions and Answers / Quantifying Memory Requirements for a Parallelized Job
« on: June 16, 2022, 19:09 »
I would like to quantify the actual memory requirements for a parallelized job on a cluster since some jobs have run out of memory in the past due to insufficient RAM from each node. How can we calculate the memory requirements for an entire job calculation (how do we quantifiably determine it from the *.log file where it provides memory per k-pt, per dense matrix dimension, and per real-space grid)? A snippet of the memory requirement from a previous *.log file is shown below:
+------------------------------------------------------------------------------+
| K-point grid: 4 x 4 x 4 |
| Number of irreducible k-points: 32 |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| Real space grid sampling is (209, 209, 209) in a, b, and c directions. |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| Memory requirements for the calculation |
+------------------------------------------------------------------------------+
| Dense matrices: 1.52 GB per matrix [Matrix dimensions 9984 x 9984] |
| Total memory required per k-point: 4.56 GB |
| |
| Storage of real-space orbitals: Enabled |
| Storage requires 306 MB |
| |
| Total memory required per real-space grid: 139 MB |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| SCF History |
+------------------------------------------------------------------------------+
| Memory required to store SCF history: 10.02 GB |
| Number of history steps: 20 |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| K-point grid: 4 x 4 x 4 |
| Number of irreducible k-points: 32 |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| Real space grid sampling is (209, 209, 209) in a, b, and c directions. |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| Memory requirements for the calculation |
+------------------------------------------------------------------------------+
| Dense matrices: 1.52 GB per matrix [Matrix dimensions 9984 x 9984] |
| Total memory required per k-point: 4.56 GB |
| |
| Storage of real-space orbitals: Enabled |
| Storage requires 306 MB |
| |
| Total memory required per real-space grid: 139 MB |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| SCF History |
+------------------------------------------------------------------------------+
| Memory required to store SCF history: 10.02 GB |
| Number of history steps: 20 |
+------------------------------------------------------------------------------+
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General Questions and Answers / Quantitative Analysis of Total Interface Trap Density
« on: August 2, 2021, 07:35 »
Hello QuantumATK Staff,
I am interested in determining the total interface trap density at a given interface using the LDOS (eV-1* Ang-3) results (please see "ldos_example_interface_states.png" below). I have tried to integrate the LDOS with respect to energy at the interface region (Z - Zint = 0 Angstroms, blue rectangular region) across a 10 Angstrom region along with a unit conversion to cm-2, but I always seem to get a value that is > 1e14 cm-2. This is far too high in comparison to outside literature. I wanted to ask if the LDOS magnitudes are quantitatively meaningful to perform integration on them or if I should avoid doing this? I notice that when I evaluate the LDOS magnitudes at Z - Zint = 0 Angstroms (please see "ldos_example_z_slice_z_zint_0.png"), the magnitude is between 1e18 to 1e23 eV-1* cm-3 which is really high. Looking at the LDOS magnitudes 200 Angstroms to the left of the interface region shows a floor value around 1e16 to 1e17 eV-1* cm-3 (please see "ldos_example_z_slice_z_zint_n200.png"). If integration for obtaining the total interface trap density is valid, I am not sure if I simply subtract the LDOS magnitude of the -200 Angstrom position from the LDOS magnitude of the 0 Angstrom position, shift the LDOS magnitude to start at 1e16 eV-1* cm-3 , or just normalize the magnitude? I can provide any other files and clarify my question(s) if necessary. Thank you in advance.
I am interested in determining the total interface trap density at a given interface using the LDOS (eV-1* Ang-3) results (please see "ldos_example_interface_states.png" below). I have tried to integrate the LDOS with respect to energy at the interface region (Z - Zint = 0 Angstroms, blue rectangular region) across a 10 Angstrom region along with a unit conversion to cm-2, but I always seem to get a value that is > 1e14 cm-2. This is far too high in comparison to outside literature. I wanted to ask if the LDOS magnitudes are quantitatively meaningful to perform integration on them or if I should avoid doing this? I notice that when I evaluate the LDOS magnitudes at Z - Zint = 0 Angstroms (please see "ldos_example_z_slice_z_zint_0.png"), the magnitude is between 1e18 to 1e23 eV-1* cm-3 which is really high. Looking at the LDOS magnitudes 200 Angstroms to the left of the interface region shows a floor value around 1e16 to 1e17 eV-1* cm-3 (please see "ldos_example_z_slice_z_zint_n200.png"). If integration for obtaining the total interface trap density is valid, I am not sure if I simply subtract the LDOS magnitude of the -200 Angstrom position from the LDOS magnitude of the 0 Angstrom position, shift the LDOS magnitude to start at 1e16 eV-1* cm-3 , or just normalize the magnitude? I can provide any other files and clarify my question(s) if necessary. Thank you in advance.
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