title: On the origin of photoluminescence in silicon nanocrystals: pressure-dependent structural and optical studies.
abstract: A lack of consensus persists regarding the origin of photoluminescence in silicon nanocrystals. Here we report pressure-dependences of X-ray diffraction and photoluminescence from alkane-terminated colloidal particles. We determine the diamond-phase bulk modulus, observe multiple phase transitions, and importantly find a systematic photoluminescence red shift that matches the X(conduction)-to-Γ(valence) transition of bulk crystalline silicon. These results, reinforced by calculations, suggest that the efficient photoluminescence, frequently attributed to defects, arises instead from core-states that remain highly indirect despite quantum confinement.
authors: Department of Chemistry, Northwestern University, Evanston Illinois 60208, USA.
authors: Daniel C
authors: DC
authors: Hannah
authors: Jihua
authors: J
authors: Yang
authors: Paul
authors: P
authors: Podsiadlo
authors: Maria K Y
authors: MK
authors: Chan
authors: Arnaud
authors: A
authors: Demortière
authors: David J
authors: DJ
authors: Gosztola
authors: Vitali B
authors: VB
authors: Prakapenka
authors: George C
authors: GC
authors: Schatz
authors: Uwe
authors: U
authors: Kortshagen
authors: Richard D
authors: RD
authors: Schaller