MSE Masters Thesis Final Presentation: Timothy Lou

MSE Masters Thesis Final Presentation: Timothy Lou

TITLE: Fabrication and Excitation Transfer Investigation of Chalcopyrite Nanocrystal-Gold Nanoparticle Hybrid Structures

ADVISOR: Björn Reinhard MSE, CHEM

COMMITTEE: Maria Kamenetska MSE, Physics; Dr. Xi Ling - CHEM

ABSTRACT: HgCdTe-based detectors dominate infrared detection technology due to their large spectral range and high quantum efficiency. Current efforts aim to improve the size, cost, and enable room-temperature detection. However, device performance at elevated temperatures is significantly limited by point defects, particularly mercury vacancies. These defects introduce trap levels that degrade carrier lifetimes and increase the dark current. Despite their importance, the energetic positions of these vacancy-related traps remain unknown. In this work, we employ density functional theory (DFT) methods combined with device simulations to study the properties of mercury vacancies and their impact on device performance. The initial atomistic simulations investigate the impact of alloy disorder and strain on the electronic properties of the alloys, as well as the energetic positions of the mercury vacancies inside the bandgap as a function of alloy composition. Subsequently, we use the DFT results to compute the nonradiative carrier capture rates of the vacancy levels. The results are then integrated into drift-diffusion models to study their impact on the current-voltage (I-V) characteristics, trap-assisted-tunneling (TAT) rates, and random telegraph signal (RTS) noise phenomena in HgCdTe detectors.