| Electrode-Limited Conduction Mechanisms | Bulk-Limited Conduction Mechanisms |
| 1. Schottky emission | 1. Poole-Frenkele emission |
| 2. Fowler-Nordheim tunneling | 2. Hopping conduction |
| 3. Direct tunneling | 3. Ohmic conduction |
| 4. Thermionic-field emission | 4. Space-charge-limited conduction |
|
| 5. Ionic conduction |
|
| 6. Grain-boundary-limited conduction |