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By Arun Goud Akkala1, Sebastian Steiger1, Jean Michel D Sellier2, Sunhee Lee1, Michael Povolotskyi, Tillmann Christoph Kubis1, Hong-Hyun Park1, Samarth Agarwal3, Gerhard Klimeck1, James Fonseca1, Archana Tankasala1, Kuang-Chung Wang1, Chin-Yi Chen1
1. Purdue University 2. Private Oil and Gas Company 3. IBM
Poisson-Schrödinger Solver for 1D Heterostructures
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Version 3.0.7 - published on 27 Aug 2015
doi:10.4231/D3QR4NR6C cite this
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11 Feb 2010
3.0 out of 5 stars
I studied the “1D Heterostructure Tool” which is a simple Poisson Schrodinger solver for 1D heterostructures. This tool has recently been updated as of May 8, 2009. Although it is a useful tool with many benefits, I feel that some added features would make it significantly more useful.
The current materials that are available for this tool are GaP, AlAs, AlP, GaAs, InAs, and AlGaAs. A maximum of 16 layers plus the substrate can be chosen. For each layer you are allowed to pick the material, alloy compostion, n-type doping level, and thickness/# of monolayers. There is also an option to add a delta doping layer. A nice feature of the tool is that once you choose your layer structure you can quickly view a flat-band energy diagram of the design before simulating in order to ensure that you have your desired design. After the geometry is selected you can choose the minimum and maximum gate voltages along with the voltage step size. This is used for determining the voltage range that the electron sheet density of each layer is calculated for. You must also select whether to calculate the electron density using a model based on the Schrodinger equation or a model using the Thomas-Fermi calculation.
Since the tool is a simple Poisson solver the simulation only takes a few moments. Therefore, the major benefit of this tool is the quick visualization of simple heterojunction structures. The important outputs of the tool are the conduction band and the electron density. Thus, the tool’s main use is to quickly observe heterojunction interfaces like those of an AlGaAs/GaAs HEMT.
I believe that this tool could be incredibly more useful with a few improvements and added features. An obvious improvement is the addition of more materials. Besides from just more semiconductor materials, it would also be useful to add some metals that could be used as contacts. Currently the tool just solves for the conduction band and electron density at zero gate bias, but a more applicable tool would allow for an applied gate bias or at least a top metal contact with a specified Schottky barrier. Also, the Fermi level is currently an input value chosen by the user. I think it would be more appropriate and accurate if the Fermi level was calculated by the tool itself based on the device geometry. Another important addition would recognize the importance of p-type devices. The development of devices with high hole mobility is essential to the advancement of semiconductor technology, but this tool only allows for n-type doping. It also only calculates the conduction band and electron density. Showing the valence band and hole density would be essential for the modeling of a p-type device such as a p-channel high hole mobility transistor (HHMT). Another important aspect of p-type devices is the use of strain. It would be interesting if based on the layer structure the tool could calculate the strain of each layer, and consequently the effect of the strain on the energy band.
Overall, I think this tool is useful for visualizing simple heterojunction interfaces but requires some added features in order to be applicable for modeling more interesting and complicated devices.
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