Nitride Semiconductor Tunnel Junction Doping for Lower Forward Voltage

The patent divides the n-type semiconductor layer into multiple segments with different impurity concentrations and thicknesses. Specifically, it creates a first n-type semiconductor layer with higher impurity concentration and smaller thickness, and a second n-type semiconductor layer with lower impurity concentration and larger thickness. This segmentation allows the formation of a tunnel junction that enables light emission while managing forward voltage through the distributed impurity profile.

The patent applies local quality by creating regions with different impurity concentrations within the n-type semiconductor layer. The first n-type semiconductor layer has a higher impurity concentration optimized for tunnel junction formation, while the second n-type semiconductor layer has a lower impurity concentration. This spatial variation in impurity concentration allows different regions to serve different functions, enabling light emission while controlling forward voltage characteristics.

The patent changes the impurity concentration parameter by creating a gradient structure where the first n-type semiconductor layer has a higher impurity concentration than the second n-type semiconductor layer. This parameter change allows the formation of a tunnel junction with sufficient electron passage probability while the varying concentration profile helps manage the depletion layer width, preventing it from becoming excessively large.

The patent addresses the depletion layer width issue by introducing a vertical dimension to the impurity concentration profile. Instead of a uniform concentration, it creates a layered structure with different concentrations at different depths, allowing electron passage through the tunnel junction while distributing the depletion region across multiple layers with varying properties.