I am not actually talking here about SiGe(Silicon-Germanium hybrids) but an integrated circuit that uses entirely Germanium(doped of course in certain areas)? It is my understanding that even though Germanium was used to make the first discrete transistors, there are many problems with using it as a substrate for IC fabrication. Such as the fact that Germanium Dioxide is water soluble.
Electronic – How close are we to fabricating a Germanium IC
integrated-circuitsemiconductors
Related Solutions
You can drive a small bipolar stepper motor using an L293, SN754410, or L298
If you find a unipolar stepper motor (not uncommon in the paper advance on cheap printers) you can drive that relatively easily with discrete NPN transistor switches. In theory you can do a bipolar motor that way, but the circuit is a bit trickier (it's easy to get both the high and low transistors on and as a result short out the power supply, making them rather warm). Besides printers (copiers?) floppy drives are another salvage source, but hard drives switched to voice coils ages ago. Lots of surplus outfits will sell you motors; if you aren't looking for something powerful enough to run a machine tool you probably won't have to spend much.
Since you are very new to embedded programming as well, you might want to look at one of the "motor shield" type solutions - not necessarily to buy (though of course that is an option) but to study the plans and example software.
If working with a salvaged motor for which you don't have data, start with low voltage/current until you get movement. One thing that can be interesting to do is to take a <1 amp power supply and work out the series of voltage applications to the winding by hand connnecting them to slowly step the rotor. You can buy chips such as the L297 which generate this sequence to control the power driver chip, or you can do it yourself in software.
Actually making a motor may be fairly tricky, but people do make brushlesss motors which are stepper's lower-pole-count cousins. For early experiments ball bearings are likely not your greatest concern - plastic or oil-impregnated bronze sleeves might serve. But rollerblade wheel bearings are fairly cheap: mounting them is going to be a big part of the challenge (and a challenge which starts to stray from the topic of EE stackexchange)
No big deal really. First you get a pile of silicon. A bucket of ordinary beach sand contains a lifetime supply if you're going to make your own chips. There is lots of silicon on this planet, but it's mostly all so annoyingly bound up with oxygen. You have to break those bonds, discard the non-silicon stuff, then refine what's left over.
You need very very pure silicon to make useful chips. Just smelting the silicon oxide into elemental silicon isn't anywhere near enough. The bucket of sand was mostly silicon dioxide, but there will be little bits of other minerals, bits of snail shells (calcium carbonate), dog poop, and whatever else. Some of elements from this stuff will end up in the molten silicon mix. To get rid of this, there are various ways, most having to do with very carefully allowing the silicon to crystalize at just the right temperature and rate. That ends up pushing most of the impurities in front of the crystallization boundary. If you do this enough times, enough of the impurities get pushed to one end of the ingot, and the other end might be pure enough. To be sure, you wave a dead fish over it during a full moon while thinking only pure thoughts. If it turns out later that your chips are no good, then one possibility is you botched this step by using the wrong species for fish or that your thoughts weren't pure enough. If so, repeat back from step one.
Once you have pure crystalline silicon, then you're almost done, just another 100 steps or so that all have to be just right. Now cut your pure silicon into wafers. Maybe that can be done with a table saw or something. Check with Sears to see if they sell silicon-ingot-cutting blades.
Next polish the wafers so that they are very very smooth. All the rough stuff from the table saw blade needs to be gone. Preferably get it down to a wavelength or so of light. Oh, and don't let oxygen at the open surface. You'll have to flood your basement with some inert gas and hold your breath for a long time while you finish the polishing.
Next you design the chip. That's just wiring a bunch of gates together on a screen and running some software. Either spend a few 100s of k$ or make your own if you've got a few 10s of man-years free. You can probably do a basic layout system, but you'll have to steal some trade secrets to be able to do the really good stuff. The people that figured out the really clever algorithms spent many M$ doing it, so don't want to give out all the cool bits for free.
Once you have the layout, you'll have to print it on masks. That's just like regular printing, except for a few orders of magnitude finer detail.
After you have the masks for the various layers and photolithography steps, you need to expose them onto the wafer. First you slather on the photoresist, making sure it has a uniform thickness to within a fraction of the wavelength of the light you will use. Then you expose and develop the resist. That leaves resist over some areas of your wafer and not over others, just like the mask specified. For each layer you want to build up or etch or diffuse into the chip, you apply special chemicals, usually gasses, at very precisely controlled temperatures and times. Oh, and don't forget to line up the masks for each layer in the same location on the wafer to a few 100 nm or better. You need really steady hands for that. No coffee that day. Oh, and remember, no oxygen.
After a dozen or so mask steps, your chips are almost ready. Now you should probably test each one to find out which ones hit impurities or got otherwise messed up. No point putting those into packages. You'll need some really really tiny scope probes for that. Try not to breath as you're holding a dozen probes in their targets to within a few µm on the special pads you designed into the chips for that purpose. If you've done the passivation step already, you can do this in a oxygen atmosphere and take a breath now.
Almost done. Now you cut up the wafer into chips, being careful to toss out the ones you found earlier were no good. Maybe you can snap them apart, or saw them, but of course you can't touch the top of the wafer.
You have the chips now, but you still need to connect to them somehow. Soldering on silicon would make too much of a mess, and soldering irons don't have fine enough tips anyway. Usually you use very thin gold bond wires that are spot welded between the pads on the chip and the inside of the pins of whatever package you decide to use. Slap on the top and glob on enough epoxy to make sure it stays shut.
There, that wan't so bad, was it?
Best Answer
We are not close to making pure Ge ICs, and likely never will be. The odd diode or power device where the low voltage wins, yes, but the process technology for significant integration, no.
The technology to be able to process silicon into ICs as we do today has been won over 40 to 60 years (depending on your start date) of painstaking incremental investment. Given a choice between a tweak that uses the existing silicon processes (continue to reduce dimensions, alloy Ge with it, put it on an insulating sapphire substrate) and a totally new material to learn how to process and handle the chemistry, the choice will be for silicon, unless there is some huge advantage for the new material.
A big, big drawback for straight Ge is the low temperature performance of the material. You can't solder ICs by bringing the whole board up to temperature as you can with silicon, it's hand solder leads or clamp only, and then use excellent heatsinking. What the market wants in higher temperature performance, that's one of the things driving SiC for instance.
IC require much more than discretes, every aspect of the physics and chemistry, the resistors, the well capacitance, the oxide stability, the interconnect metals, the lattice sizes to mention a few from a long list, all form part of a system within which the IC designers work.
Discretes are a little more forgiving, and here new materials do get used at a low level of integration. GaN is making higher speed FETs, SiC is making higher voltage higher temperature transistors, SiGe first appeared in discretes for a decade or two where the teething troubles were sorted out, then there's InGaP, and AlGaAs, and a host of others, and Ge too for some specialist diodes and power transistors.
Given how long Ge has been around, it's obvious that there is not a sufficient performance advantage to make it worth trying to work with the material's problems on any significant scale.