Bandgap evolution of diamond

As an indirect-bandgap material, diamond owns an inter-band transition absorption belonging to the phonon-assisted indirect transition process whose image is complex due to a many-body interaction among electrons, phonons, and photons. Therefore, research on the indirect bandgap of diamond has been a bottleneck hard to break through. Here, systematical measurement and analysis are conducted on the temperature dependence of phonon-assisted intrinsic absorption edge of high-quality electronic-grade diamond in a wide range (10–620 K). Combined the findings with an image model of the indirect phonon-assisted transition of diamond, a more accurate bandgap value of diamond (Eg = 5.480 ± 0.004 eV) is obtained with the temperature dependence of its bandgap also measured in a wide temperature range in detail. According to the results obtained, this work is hoped to offer more accurate reference for diamond in the aspects of indirect bandgap and temperature dependence.