Argon-Assisted Glancing Angle Deposition

• Author / Creator

  Sorge, Jason B

• Glancing angle deposition (GLAD) is a physical vapour deposition (PVD) technique capable of fabricating highly porous thin films with controllable film morphology on the 10 nm length scale. The GLAD process is flexible and may be used on virtually any PVD-compatible material. This makes GLAD a useful technique in many applications including photovoltaics, humidity sensing, and photonic devices. Conventional, dense films grown at normal incidence concurrent with ion or energetic neutral bombardment have been reported to have higher film density than unbombarded films. In a similar sense, highly porous GLAD films grown with concurrent bombardment should generate films with new interesting properties and extend the versatility of the GLAD process. The research presented in this thesis investigates the use of energetic neutral bombardment during GLAD film growth to produce new film morphologies. Here, with increasing bombardment, the column tilt increases, film density increases, and specific surface area decreases. A film simultaneously exhibiting high column tilt angle and film density is enabled by incorporating bombardment concurrent with GLAD film growth. This in turn results in films with larger principal refractive indices, but a smaller normalized in-plane birefringence. Bombarded films were also found to be compatible with the phisweep process which helps decouple the column tilt angle from film density. Characterization of the bombardment-assisted growth process indicates that both sputtering and bombardment-induced diffusion play a role in the modification of film morphology. The film property modifications which arise as a result of bombardment-assisted growth lead to device improvements in a number of applications. Bombardment was used to fabricate square spiral photonic crystal structures with increased column tilt which bear a closer resemblance to optimized simulated structures than conventionally-grown GLAD films. The increase in column tilt angle and film density were found to be beneficial in the fabrication of circular polarization filters, where bombarded films were found to exhibit larger selective circular behaviour than in unbombarded films. The morphology modification was also found to be beneficial in humidity sensing applications where the bombarded films demonstrated an increase in the capacitive response.

• Subjects / Keywords

  • Argon
  • Angle
  • Glancing
  • Bombardment
  • Deposition
  • Assisted

• Graduation date

  Fall 2012

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3SW2Q

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.