The downside of trying to use an Android tablet for Note-Taking.

One of the applications for generic Android tablets which I’ve tried to find solutions to, mainly in the form of apps, would have been, for note-taking. And this quest has largely remained unsatisfied. I’d like to comment on Why.

When I wanted to use my tablet for note-taking, the way I visualized doing this, was to be able to jot down notes by hand, as if on paper. The idea seemed natural, that a tablet could store many pages of notes, without requiring that the user carry with him, stacks of sheets and binders.

But the main impediment I saw with this actually stemmed from the hardware itself, that is sometimes just referred to as the Glass of the tablet, or otherwise, as the Sensor. Most common tablets have a capacitance-based Sensor, which is best-suited, for detecting the proximity of a human fingertip. A necessary variation in its use is, a passive stylus, which does little better, than to focus electrostatic fields, as any shaped, conductive object would. This type of stylus requires no special hardware from the tablet to work, and can also be bought from virtually any manufacturer, and can remain compatible with the standard sensor.

The problem with that which ensues, is the fact that actual software – i.e., apps – try to implement a feature which is called ‘Palm Guard’, ‘Palm Rejection’, or ‘Wrist Guard’. This feature recognizes the fact that when people try to write on any surface, we usually have a tendency to rest the side of our hand on the same surface. The capacitance-based sensors cannot distinguish between contact with a human hand, and the point of the stylus. The ability of the software to make the same distinction is only as effective, as the ability of the sensor to be hugely multi-touch in the ‘contact-map’, that it inputs.

(Updated 12/26/2018, 12h00 : )

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Intrinsic Silicon

Many people already understand, that two types of silicon exist, N+ -Doped, and P -Doped.

Well I’ve known for some time, that another type of silicon which exists, is called ‘Intrinsic Silicon’. This is a form of silicon, which theoretically contains no dope at all, and which is therefore non-conductive. It’s not even a semiconductor in that state.

This type of silicon might be of some interest in the design of modern Integrated Circuits, especially in the reduction of the capacitance of individual transistors. But there areĀ  essentially two problems with its use:

  1. It’s practically impossible for the silicon to be perfectly pure. The concentrations of Dope, in the N+ or P -Doped silicon, are already extremely low. The concentration of impurities in Intrinsic Silicon is simply lower, industrially, than in the intentionally-doped silicon, not truly zero. And what this means in practice, is that ‘larger pieces’ of Intrinsic Silicon are still partially conductive. In fact, how low the concentrations of N+ or P -Dope can be brought in the industrial process, depends on how low the level of impurities is, in the silicon, to begin with. In either type of intentionally-doped silicon, the concentration of dope must still be at least one order of magnitude greater, than the level of impurities was.
  2. Actually, I think that Intrinsic Silicon is more expensive in bulk, than either type of intentionally-doped silicon, which means, that if the entire wafer needed to be made out of it, since the substrate of the wafer is meant to provide mechanical support as well, then the cost of the manufacturing process would increase.

Yet, small pieces of Intrinsic Silicon, as the following image shows, can still be used to provide lateral insulation, between the P -Doped and the N+ -Doped wells of individual transistors, where a “buried oxide layer” provides vertical insulation between those wells, and the actual wafer:

And, it would be my expectation that because Intrinsic Silicon is ‘non-conductive’, larger pieces of it should also be optically transparent, which means that some people might mistake it for glass.

By definition, glass would be ‘amorphous’, which means ‘not crystalline’, which would make actual glass useless as a semiconductor. However, amorphous forms of silicon can readily be used in the design of wafers, as long as they do not need to participate in the actual semiconductive behavior between N+ and P -Doped silicon.