Viability of 3-D printing semiconductors of Zinc Antimonide in transistors
Our team is trying to develop a way to print a Zinc Antimonide (ZnSb) semiconductor transistor.
- Brief description of the semiconductor material with a link to the manufacturer(s) or suppliers
Benefits of 3D Printing
The core benefit of using the 3D printing approach of electronic device creation is the flexibility that is inherent to the process. Provided suitable materials and schematics are available it is possible to build any combination of devices. The transistor is a small but very potent part of this flexibility. Once a suitable transistor is designed, numerous electronic circuits of interest can then be fabricated such as logic gates, amplifying circuits and device control switches. Not only can these devices be created, they can be scaled to suit specific needs.
It would be possible then for a suitably equipped 3D printer to not only be able to print "smart" parts that could electronically interface with each other, but to also build control circuits used to run the printers. Some applications could include building control board for running newer versions of 3D printers that not only handle the operational control functions of running stepper motors and controlling current to the extrusion head, but also sensing capabilities that could be directly integrated into the components used to build the printers. integrating sensing circuits into printed components would allow for feedback signals that could permit higher quality parts to be printed with less waste due to part scrapping.
Method of Printing Transistors
The bulk of the 3D printed part can be constructed using traditional extrusion methods to build up the surfaces and component as desired. The printing of the transistor and associated trace leads would require the creation of a flat smooth surface. To achieve this desired surface after creating the plane where the transistor is to be located, several layers of polyurethane should be used to fill in small surface defects left behind by previous passes with the extrusion head.
The simplest solution to applying the polyurethane is to use a modified Ink-Jet printing cartridge. The purpose of the inkjet head is to provide a controllable fine droplet pattern similar to that achieved by a spray head used for coating surfaces with polyurethane. The layers should be applied in successive passes avoiding delays between each layer to ensure that the layers fully bond to each other and to allow the liquid polyurethane to "float" the surface to achieve as smooth and flat a surface as desired. Because the method relies on the polyurethane to "float" the surface, the applying of transistors is limited to work in the flat plane that is normal to the pull of gravity. This will require some care in the setup of the printer itself as the liquid polyurethane may tend to run if applied to a surface that is not level. This may be somewhat controlled by building up an extruded dam of material prior to applying the polyurethane forming a lake or pool for the polyurethane to cure in
Once the flat surface is achieved the ZnSb semiconductor can be applied to create the semiconductor N-P-N junction. Additionally silver ink (need Xerox reference here) may be applied to create conductive traces to carry the signals to and from the transistor. Both the silver ink and the transistor material will need to be cured after application. One possible method of curing the material is the use of a small radiant heating element fitted to the extrusion carriage so that the heat may be applied only where desired to avoid unnecessary thermal input back into the previously extruded material.
After the thermal treatment of the material several additional coatings of polyurethane may be applied to protect the circuit traces and the transistor junction itself. In much the same way that traditional printed circuit boards use vias to provide electrical connection between layers, portions of the circuit may be "masked" off to allow for an electrical equivalent. In places where it is desired to provide interconnection between layers the polyurethane may be excluded during the recoating process.
After the new layer is applied an additional transistor and circuit traces may be applied to increase the density of electrical components within the device. The limitation here is the possibility of electrical interference from adjacent layers due to induced signals from one layer to the next. This along with concerns of dissipating thermal energy will require some ingenuity and experimentation on the part of the daring user.
Steps of Synthesizing
Doping the ZnSb with copper will create a p-type material. To do this a combination of heating, quenching, and ball-mill crushing will be implemented. All the granular metals (Zinc, Antimony, and Copper) will be together in a container and placed in a furnace. With the furnace set at 1073K for 24 hours, with the occasional rocking. The granular pieces after the furnace will be left to cool at room temperature. Using a ball-milling machine with an argon atmosphere for 1-1.5 hours to finely crush the granulars, similar to the process in . To get a printable viscosity a process similar to . For this we will use the chemicals α-terpineol and DisperBYK-110. For every 10 grams crushed ZnSb 10 milliliters of α-terpineol will be used and 1 milliliter of DisperBYK-110 and make sure that it is mixed well.
Doping the ZnSb with Tellurium will create an n-type material. To get an n-type ZnSb is very difficult, but can do done. A study , shows that there has to be a certain atomic weight percent of Tellurium, which is 2.06at%. The process of creating the n-type ZnSb is to heat the the granular Zinc and Antimony with the powdered Tellurium at 923 in an ampoule then water quenching the ampoule. After the doping process the same preparation as the p-type paste would be used to create the n-type paste.
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equipment, processes, chemicals, steps involved. Show alternate paths and discuss the optimal route and the metrics for choosing it.
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used to determine if you obtained your target compound.
- A list of best in class material properties for your ink.
- Discuss the characterization methods and how they could be adapted for in-situ analysis.
- List and describe applications of this semiconductor if it is printed.
- Make a basic diagram for an electronic device that could use this semiconductor and post
diagram in your project page.
- Design the semiconductor portion of the device in OpenSCAD, paste the code directly
into your project page
- Post the STL of your design and a link to the STL on your project page.