Ultrafast transient photoinduced absorption in Ge core and Ge/GeO2 core/shell nanoparticles: effect of interface passivation
Abstract
Transient photoinduced absorption in Ge core and Ge/GeO2 core/shell nanoparticles (NPs) has been studied in visible spectral range. Two distinctive relaxation processes were observed: the fast relaxation with lifetime of several picoseconds corresponds to the carriers transfer from the excitation region to the surrounding interface or defect-related states, and the slow relaxation (tens of picoseconds) is correlated with the carriers through the interface-related states toward the indirect lowest energy states. Time-resolved studies show that the passivation of GeO2 shell significantly reduces the density of interface state and suppresses the rate of carrier trapping in Ge/GeO2 core/shell structure, which provides an alternative method to modulate the optical properties in NPs.
- Publication:
-
Applied Physics A: Materials Science & Processing
- Pub Date:
- March 2011
- DOI:
- 10.1007/s00339-010-6132-z
- Bibcode:
- 2011ApPhA.102..527W
- Keywords:
-
- Pump Pulse;
- Carrier Trapping;
- Carrier Relaxation;
- Excitation Photon Energy;
- Charge Storage Device