Stacking fault formation mechanism and suppression during GaP nucleation on silicon

We investigate stacking fault formation during gallium phosphide (GaP) nucleation on silicon by metal organic vapor-phase epitaxy and identify the dominant parameters controlling defect generation. We demonstrate that stacking faults nucleate during flow-modulated epitaxy of the GaP seed layer, not at the Si/GaP interface or during subsequent cap layer growth. A mechanistic model linking island growth mode and surface kinetics to stacking fault formation is developed and supported by experimental data demonstrating control over stacking fault density. The TEGa molar flow rate and the break duration during pulsed deposition are identified as the dominant process parameters: An optimal TEGa flow slightly below one monolayer per pulse minimizes island aspect ratio and reduces stacking fault nucleation sites, while sufficient break duration enables adatom diffusion to energetically favorable lattice sites. Total break duration dominates over its distribution between precursor pulses, with preferential placement after the TEGa pulse. Applying these findings, we achieve single-plane stacking fault densities below 2 × 104 cm−2 and stacking fault pyramid densities below 1 × 104 cm−2, exceeding the quality of previously reported GaP nucleation layers by more than one order of magnitude. Our findings demonstrate that systematic control of both growth mode and surface kinetics, achieved through suitable growth parameters, enables reproducible fabrication of low-defect GaP nucleation layers on silicon, paving the way for high-quality device integration.