Point defect–dislocation interactions in BEOL-compatible Ge-on-Si epitaxy

Reduced thermal budget is required for back-end-of-line (BEOL) integration of application specific functionality into the multilevel metal stack a processor “substrate.” We report 400 °C BEOL-compatible Ge-on-Si growth (LT Ge) that epitaxial and single crystalline with defect density similar to high temperature small 0.05% tensile strain. Room methanol–iodine passivation employed pre-growth in lieu typical 800 oxide removal step. Undoped LT Ge exhibits p-type conductivity initially n-type conversion upon annealing. Hall effect measurements following post heat treatment between 600 reveal an acceptor reaction follows first-order kinetics activation energy 1.7 ± 0.5 eV pre-exponential factor 2.3×107 s−1 consistent point defect, diffusion limited process. also observe 90° sessile dislocations identified via transmission electron microscopy are annihilated same regime, which evidence defect-mediated climb. Ensuring high-quality epitaxy by characterizing reactions process flow key enabling vertical optical interconnects.