Failure Analysis of Infrared Sensing Devices due to Cryogenic Cooling

Date

2023-6-02

Author

Baloğlu, Eyüp Can

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Development of Infrared Focal Plane Array (IRFPA) structures have become increasingly important in recent years due to their applications in a wide range of fields, including thermal imaging, remote sensing, security, surveillance, earh observation and astronomy. Semiconductor compounds used in IRFPA technologies are typically exposed to a wide range of temperatures during their operation and storage. Temperature-dependent material properties, such as thermal expansion coefficient, elastic constants, and heat capacity, play a crucial role in the performance and reliability of IRFPA devices. Therefore, it is important to have accurate and reliable temperature-dependent material properties for these materials. Having complete and accurate information about material properties is required for designing and optimizing IRFPA devices. In this thesis, Density Functional Theory (DFT) is implemented within quasi-harmonic approach to define temperature dependent material properties which is the first attempt for the selected III-V and II-VI semiconductor compounds (GaSb, InSb, CdTe, HgTe, ZnTe, CdZnTe). Both LDA and PBEsol approximations are used to obtain thermo-elastic material properties. Nanoindentation experiments on GaSb are conducted at room temperature to verify obtained material properties such as elastic modulus and Vicker’s hardness by DFT. Experimental results show good coherence with numerical outcomes of DFT for GaSb material. To mimic operation conditions of IRFPA structures at cryogenic temperatures, a custom test setup with cryocooler is designed. Crack initiation and propagation of GaSb and CdZnTe materials on SS304 material due to developed thermo-mechanical stress by cryocooling are investigated with this test setup and scanning electron microscopy (SEM) is used to observe cracks at room temperature. Thermo-mechanic stress determinations on bimaterial assemblies as well as on a representative IRFPA structure are performed with finite element simulations to show determined stress dependence on defined material properties. A novel phase field fracture model is developed to simulate crack initiation and propagation for materials that belongs to cubic anisotropy. Anisotropic energy based failure criterion that splits the free energy and eventually crack driving source into isotropic and anisotropic parts is used. Representative numerical example with a notched geometry is also provided for different in plane material orientations of GaSb. Obtained material properties of GaSb by DFT are used as material inputs of phase field fracture simulations. Both numerical and experimental investigations on semiconductor materials are performed. A novel and complete framework on failure analysis of IR sensing materials that cover from temperature dependent material property determinations to crack initiation/propagation subjects is developed.

Subject Keywords

Cooled infrared detectors, Temperature dependent material properties, Density functional theory, Nanoindentation, Fracture in cubic anisotropic materials

URI

https://hdl.handle.net/11511/104530

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Graduate School of Natural and Applied Sciences, Thesis