Phys.org May 7, 2024
The nature of enhanced photoemission in disordered and amorphous solids is an intriguing question. An international team of researchers (Russia, USA – UC Irvine) studied structural photoemission in heterogeneous cross-linked silicon glass, a material that represents an intermediate state between the amorphous and crystalline phases, characterized by a narrow distribution of structure sizes. The model system showed a clear dependence of photoemission on size and disorder across a broad range of energies. While phonon-assisted indirect optical transitions are insufficient to describe observable emissions, their experiments suggested these could be understood through electronic Raman scattering. They attributed photoemission in the disordered system to the presence of an excess electron density of states within the forbidden gap where electrons occupy trapped states. Transitions from gap states to the conduction band were facilitated through electron–photon momentum matching. According to the researchers their findings emphasize the role of photon momentum in the optical response of solids that display disorder on the nanoscale… read more. TECHNICAL ARTICLE
Graphical abstract. Credit: ACS Nano 2024, 18, 13, 9557–9565, March 4, 2024