No real crystal is perfect
Up to now we've been drawing pristine, perfect lattices. In reality every crystal has imperfections, and how we manage them is a huge slice of semiconductor engineering. Some defects are bad (they slow electrons down). Some defects are essential (they're how we make a transistor work at all).
Why does the Crystal Purity Factor appear in Simon's Law? Because the law projects how a Crystal-EM device performs vs silicon — and that comparison is unfair if your test crystal is full of vacancies. Industrial GaN purity has steadily improved over 20 years; that improvement alone explains a big chunk of GaN's modern performance gains. In Track 4 you'll see this parameter live in the scaling-curve dashboard.
You've completed Track 2 — Crystal Science. You understand crystals vs amorphous matter, the 7 systems, band gaps, piezoelectricity, the 8 catalog crystals, and how defects and purity shape real-world performance. You're ready to dive into the electrical side (Track 3) or, if you've already done it, the full Crystal-EM thesis (Track 4).
- Real crystals always have defects: vacancies, interstitials, dislocations.
- Random defects scatter electrons → lower mobility, more heat.
- Controlled defects (doping) are how we make n-type and p-type semiconductors — the foundation of the transistor.
- Crystal purity is a parameter in Simon's Law and shows up directly in Scaling Laws projections.