SUMMARY

The thesis focuses on advancing the field of flexible electronic devices by utilizing two-dimensional hexagonal boron nitride (2D h-BN) as a release layer. The methodology used in the thesis is the selective area growth (SAG) of III-N materials through van der Waals (vdW) epitaxy on 2D h-BN. This approach is adopted to address and solve the state-of-the-art challenges associated with InGaN/GaN solar cells and micro-light emitting diodes (micro-LEDs). The pathway to achieving efficient InGaN/GaN solar cells is impeded by degradation of the crystalline quality of the InGaN layer beyond a certain critical thickness, the phase separation of InGaN alloy at the high indium content in it, and the presence of the strong polarization charges at the InGaN/GaN hetero-interface. To overcome these challenges we propose a novel design of InGaN/GaN solar cells which includes conformally grown p-GaN, by MBE at low temperature, on top of an InGaN nano pyramid (NP) absorber, grown by nano SAG. Further, by coupling this structure with the van der walls epitaxy on 2D h-BN, two new designs of solar cells (a) conformal NP on copper, and (b) free-standing NP, are proposed. The performance of these solar cells is evaluated by optical and electrical simulations and a complete fabrication process of these solar cells is presented. The primary challenge for micro-LED fabrication has been the lowered performance of tiny micro-LEDs caused by chemical etching that defines individual LEDs and the complexity and cost associated with the lift-off and transfer of these LEDs from sapphire substrates to suitable supports. In this thesis, for the first time, we report a demonstration of coupled vdW epitaxy and SAG, to fabricate micro-LEDs of various shapes down to ultra-tiny sizes of 1.4microns. The SAG of multi-quantum wells LED heterostructures allows to obtain ultra smooth crystalline sidewalls and vdW epitaxy of 2D h-BN allows simple lift-off and transfer of micro-LEDs. The complete fabrication process of micro-LEDs and its transfer to a flexible copper substrate is performed in this thesis. Finally, device performances of these high-brightness micro-LEDs are reported. Virtual Joining Link: https://gatech.zoom.us/j/97085451177?pwd=b1g4MGI2YXcrZ1NvK0ZnSmFyNXdIZz09