Band Theory Model (Solid State Physics, Semiconductor Physics)

This is a didactic model for learning band theory.

It originated from an idea I had in my mind during class—later, when explaining to classmates, I realized that most people's understanding of energy bands was limited to "a few abstract lines." So, I created and shared this model, hoping to help more people intuitively understand band structure.

⚠️ Note

This model only displays the shape of energy bands in energy space and is a simplified version. The actual band structure of different materials will vary.

💡 Instructions

Imagine a small ball (electron) moving on the model:

• Gravitational potential energy → Analogous to the energy barrier required for electron transition
• Height difference → Analogous to different energy levels
• Bottom region → Valence band (the electron's "home")
• Top region → Conduction band (the electron's "new home" after transition)
• Band gap (sloping region) → Region where electrons cannot stay, but it contains donor energy levels (near the bottom of the conduction band, providing a "springboard" for electrons) and acceptor energy levels (near the top of the valence band, providing a "springboard" for holes)

The process of an electron transitioning from the valence band to the conduction band is analogous to a small ball climbing uphill, overcoming gravitational potential energy (energy barrier).