Discipline: Physics
Subcategory: Materials Science
Francisco Guzman - California State University San Bernardino
Co-Author(s): Paulo S. Costa, University of Nebraska-Lincoln, Lincoln, NE; Kimberly Cousins, California State University San Bernardino, San Bernardino, CA; Sara J. Callori, California State University San Bernardino, San Bernardino, CA; Erika Sanchez, California State University San Bernardino, San Bernardino, CA; Paul K Dixon, California State University San Bernardino, San Bernardino, CA; Douglas Smith, California State University San Bernardino, San Bernardino, CA; Timothy Usher, California State University San Bernardino, San Bernardino, CA; Renwu Zhang, California State University San Bernardino, San Bernardino, CA;
A novel method for fabricating ultra-thin croconic acid (CA) films with a very low surface roughness on Si wafers is reported. With a thickness of approximately 20 nm and surface roughness of ±2.0 nm, the film obtained far exceeds the quality and smoothness of previously reported CA thin films. The film is prepared by applying a high electric field in situ during thermal vapor deposition, promoting alignment of the CA molecules due to their high dipole moment. The result is compared with that of the best-reported film produced via a combination of thermal evaporation at low substrate temperature with subsequent slow heating, to demonstrate the greatly enhanced uniformness of the film. In addition, the film’s ferroelectric behavior is demonstrated using piezoresponse force microscopy measurements. A mechanism for film formation under electric field assisted deposition is proposed. Currently, the temperature dependence of this method is being studied. The substrate’s temperature is varied with temperatures exceeding below zero degrees Celsius. The films are analyzed via atomic force microscopy and piezoresponse force microscopy in an attempt to see a correlation between the applied electric field and the temperature variance.
Funder Acknowledgement(s): The authors thank the National Science Foundation for the financial support under the CREST program (NSF-HRD #1435163).
Faculty Advisor: Dr. Renwu Zhang, rzhang@csusb.edu
Role: My part in this research involved setting up the instrumentation and components needed to generate the electric field and also included depositing the films onto the substrate using the ultra-high vacuum chamber.