11. This is the basis of the optical band gap in a photonic crystal. 12. Thus we observe an increase in the apparent band gap . 13. There is a phononic band gap within a range of " normalized frequencies ". 14. This means that the semiconductors used have dissimilar band gaps . 15. Owing to their direct band gap , TMDC monolayers are promising materials for optoelectronics applications. 16. The apparent effects are : band gap reduction, valence band splitting, and optical anisotropy. 17. In conductors, there is no band gap , so the electrons are free to conduct. 18. Different from silicon with an indirect bandgap, perovskite material has a direct band gap . 19. In insulators, the band gap is " large ", and there is no conduction. 20. MOS Band gap references use lateral ( poor ) bipolar transistors for their functioning.