Mechanisms of droplet formation in pulsed laser growth of thin oxide films

Valentin Craciun; Doina Craciun; M. C. Bunescu; Eugen Vasile; A. Ioncea; Razvan V. Dabu; Ian W. Boyd

doi:10.1117/12.312756

2 July 1998 Mechanisms of droplet formation in pulsed laser growth of thin oxide films

Valentin Craciun, Doina Craciun, M. C. Bunescu, Eugen Vasile, A. Ioncea, Razvan V. Dabu, Ian W. Boyd

Proceedings Volume 3405, ROMOPTO '97: Fifth Conference on Optics; (1998) https://doi.org/10.1117/12.312756
Event: ROMOPTO '97: Fifth Conference on Optics, 1997, Bucharest, Romania

Abstract

The role of the sub-surface explosive boiling mechanism for droplet formation during the pulsed laser deposition of thin films has been examined. For photons with an energy lower than the target optical band-gap, hv<E_g, a highly perturbed target surface morphology exhibiting micrometer sized round- shaped cavities always formed, whereas for hv>E_g the surface was much less perturbed. Depth-profile estimations of the temperature profiles inside the laser irradiated targets were also quite different for these two cases. For low optical absorption coefficient (OAC) values, (alpha) < 5 X 10⁴ cm^-1, a thick layer of liquid formed whose maximum temperature was located at some point below the surface. Simultaneous to the cavity formation, the droplet density on the surface of the grown films was found to increase by orders of magnitude, indicating a clear connection between the target OAC, the temperature profile, the presence of the cavities and a high droplet density. The decrease of the OAC value during prolonged laser ablation could also explain the gradual increase of the droplet density observed when growing La_0.5Sr_0.5CoO₃ films. Based on these results, we suggest that an important fraction of the droplets on the surface of films grown under laser irradiation conditions where the OAC is smaller than 5 X 10⁴ cm^-1 is caused by an explosive sub-surface boiling mechanism.

Citation Download Citation

Valentin Craciun, Doina Craciun, M. C. Bunescu, Eugen Vasile, A. Ioncea, Razvan V. Dabu, and Ian W. Boyd "Mechanisms of droplet formation in pulsed laser growth of thin oxide films", Proc. SPIE 3405, ROMOPTO '97: Fifth Conference on Optics, (2 July 1998); https://doi.org/10.1117/12.312756

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