Manipulating incoming photons' momentum turns pure silicon from indirect to direct bandgap semiconductor

https://phys.org/news/2024-09-momentum-pure-silicon-indirect-bandgap.html

"confined photons to <few nm-scale, widening momentum distribution to that of electron momenta... photon, phonon, electron interacting at same place/ time changing electrons' energy/ momentum, enabling diagonal (in addition to vertical) transitions, improving light absorption/ emmission by 4 orders of magnitude... can reduce silicon layer thickness by same factor... outperform current technologies at fraction of cost... can be integrated into existing fabrication... silicon-based thin-film PV, optoelectronics"