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Synthesis of sub-micron cuprous oxide films on a silicon nitride membrane for study using time-resolved x-ray techniques


EMSL Project ID
17391

Abstract

We intend to study charge carrier dynamics in Cu2O with ultrafast soft x-ray pulses at the Advanced Light Source (ALS). These studies will involve measuring the evolution of laser excited electron dynamics at the L2,3 edge of Cu and potentially the K edge of O. Beamline 6.0.2 at the ALS where these experiments will be conducted requires measuring the photoinitiated change in x-ray absorption by measuring the change in transmitted x-ray intensity. Given the roughly 50 nm attenuation length of Cu2O at the L-edge and the experimental requirement of monitoring transmitted x-ray intensity we will need to grow roughly 50 nm films of Cu2O on a thin substrate with a low x-ray absorption cross-section, such as a silicon nitride membrane. The sample will also require a thin, roughly 5-10 nm passivating film to be sputtered on top of the Cu2O film to protect the layer from oxidation to cupric oxide. Ideally, this film would be composed of aluminum or another inert and relatively x-ray transparent material.
The most feasible method for producing such a thin, pure sample is through the use of molecular beam epitaxy (MBE). Igor Lyubinetsky of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL) has achieved success in growing cuprous oxide islands, nanoclusters, and nanodots on a SrTiO3(100) substrate. This work inspires confidence that this apparatus can be utilized to grow the single-phase cuprous oxide thin film necessitated by our proposed experiment. In addition, communication with Dr. Lyubinetsky indicates that a film fulfilling our experimental needs will be possible to grow using the MBE system at EMSL.

Project Details

Project type
Exploratory Research
Start Date
2006-02-21
End Date
2007-06-04
Status
Closed

Team

Principal Investigator

Kelly Gaffney
Institution
Stanford Linear Accelerator Center

Team Members

Patrick Hillyard
Institution
Stanford University