User:Cov
W5: Undecided between (semi) conductor in polymer, some in the polymer, some wet, all wet with resins/binders, and all wet with just hot plastic making everything stick in place.
W4: For variability, shelf-life (oxidation) and constant deposit rate are key. Test patterns on silicon for after-the-fact. Resistance testing is useful/common. Laser cutter can oblate/cut sections and rely on a redundant section. Acid etching may be possible. Heating and removal may be possible. "MISFET" metal-insulator semiconductor field effect transistor. Schottky diode--metal (Schottky)-semiconductor-metal (ohmic) sandwich. Work function of metal versus electron affinity in semiconductors essentially the same. Bonds covalent. Electrons move into metal and becomes less [pn]-type. Barrier forms where electrons left and voltage happens. Difference in other direction causes flow of electrons and ohmic contact. Can either vary metal or doping. Lookup leaky / Schottky diodes versus regular pn-junction. Schottky transistors also possible.
In the end we want CMOS to save material. NAND CMOS is 4 transistors. TTL has 3 transistors and 4 resistors. Also, CMOS has much better fanout. Look into verilog/VHDL output.
For Thursday: carbon. Keep thinking about deposition method. Get transparencies from John.
W3: Deposition method. Automatic dropper? Like an aquarium pump but very small. Called automated pipettes. Sticking to the sides depends on the charge, but Meehan hasn't encountered problems--gold and cadmium sulfide don't.
W2: Carbon as the Conductor material (and potentially resistors, capacitors and inductors) Step 1: Put a wire on a substrate (paste or liquid preferable to powder)
W1: document material and process choice, investigate printing, inert substrate
Materials and Processes
| Material | Doping Process | Notice |
|---|---|---|
| Silicon | Mix in during boule creation and ion implantation (particle acceleration with phosphorus or arsenic and boron or gallium) or furnace with gas (diffusion) | Need at least 10 kEv. Heat treatment for recrystallization (electrical activation) afterwards. Silicon dioxide mask for gas |
| Organic semiconductors | Beaker chemistry, dissolve into solvent | |
| Graphene | Doping during furnace and gas formation | |
| Zinc sulfide | ||
| 2-6 semiconductors | Beaker chemistry, small particle slurry |
Conductor
- Carbon, gold don't oxidize
- Aluminum, silver, copper
Recycling
- Electroplating to recover metals (different voltages for different metals)/
- Size-selective precipitation technique if p, n had different sizes
- Selective etches
- Focused ion beams to bombard off surface
