Wafer-Scale Black Phosphorus Deposition via Catalyst Layer

The patent introduces a catalyst layer as an intermediary between the phosphorus source and the semiconductor substrate. This catalyst layer mediates the deposition process, enabling phosphorus atoms to arrange into a two-dimensional black phosphorus crystalline structure rather than forming red amorphous phosphorus. The catalyst facilitates the phase transformation and structural organization needed to achieve desired material properties at wafer scale.

The patent employs molecular beam epitaxy or chemical vapor deposition techniques that precisely control deposition parameters such as temperature, pressure, and flux rates. By optimizing these parameters during the deposition process, the patent achieves formation of black phosphorus with the desired orthorhombic crystalline structure directly on the substrate, transitioning from the typical amorphous phase to the desired crystalline phase.

The patent employs an inert atmosphere or vacuum environment during the deposition and initial handling of black phosphorus samples. This inert environment prevents photocatalytic reactions and oxidation that would otherwise occur at ambient conditions, preserving the desired electrical and optical properties of the black phosphorus throughout the fabrication and transfer processes.

The patent performs the deposition and initial stabilization of black phosphorus under controlled conditions before exposure to ambient environment. By establishing the material in its desired state under protective conditions first, then transferring it to ambient conditions with appropriate protective measures in place, the patent prevents degradation that would occur if ambient exposure happened before stabilization.

The patent replaces the mechanical exfoliation process with a direct deposition process. Instead of creating bulk material and then mechanically separating layers, the patent uses molecular beam epitaxy or chemical vapor deposition to directly form two-dimensional black phosphorus layers on substrates. This substitution of mechanical processes with vapor-phase deposition enables wafer-scale production while maintaining crystalline quality.

The patent transitions from a three-dimensional bulk growth approach to a two-dimensional direct deposition approach. By depositing phosphorus atoms directly onto the substrate surface in a controlled manner, the patent forms atomically thin layers with two-dimensional crystalline structure directly, rather than reducing three-dimensional bulk material to two-dimensional flakes through exfoliation.