Intensity-dependent dynamics of photoexcited carriers in ZnO epilayers studied using pump-probe reflectance

Bing Guo; Y. H. Li; H. Ye; Peifu Gu; Kam Sing Wong

doi:10.1117/12.576597

20 January 2005 Intensity-dependent dynamics of photoexcited carriers in ZnO epilayers studied using pump-probe reflectance

Bing Guo, Y. H. Li, H. Ye, Peifu Gu, Kam Sing Wong

Author Affiliations +

Proceedings Volume 5628, Semiconductor Lasers and Applications II; (2005) https://doi.org/10.1117/12.576597
Event: Photonics Asia, 2004, Beijing, China

Abstract

The dynamics of carriers/excitons in as grown and annealed ZnO epilayers at room-temperature under high excitation densities were monitored by pump-probe(4.65/3.1 eV) differential reflectance transients on a time scale equal to 100 ps. The ΔR buildup showed a density-independent time delay of about 1.45 ps relative to the pump pulse, indicative of hot phonon effects, i.e., LO-phonon bottleneck, common to the as grown and annealed ZnO epilayers. Both appeared an initial fast ΔR decay with a time constant of about 20-25 ps due to rapid defect trapping. After the fast decay, the ΔR transient of the as grown ZnO became of sign reversal and turned to an induced absorption signal from defect levels with a decay time of several hundred picoseconds weakly dependent on excitation intensities. For the annealed ZnO, no change over in sign was observed on the slowly recovering component of ΔR, of which, in particular, the decay time was found to linearly depend upon carrier density. This finding, as confirmed by photoluminescence measurements, was attributed to a bimolecular recombination in terms of an exciton-exciton scattering in ZnO. These observations suggest that this unique pump-probe technique can provide a useful tool for understanding the defect physics of semiconducting materials.

Citation Download Citation

Bing Guo, Y. H. Li, H. Ye, Peifu Gu, and Kam Sing Wong "Intensity-dependent dynamics of photoexcited carriers in ZnO epilayers studied using pump-probe reflectance", Proc. SPIE 5628, Semiconductor Lasers and Applications II, (20 January 2005); https://doi.org/10.1117/12.576597

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available