Vertical Heterojunction Nitride Structure for High-Aspect-Ratio Channels

The patent transitions from conventional planar (2D) semiconductor structures to vertical (3D) groove-based structures. By etching grooves into the substrate and growing nitride semiconductor layers vertically within these grooves, the device achieves high aspect ratio configurations that cannot be obtained through traditional planar manufacturing methods. This dimensional change enables the channel length to be much greater than the device width, creating high aspect ratio structures essential for improved device performance.

The patent employs preliminary actions in several critical steps: First, grooves are pre-formed in the substrate with precise dimensions before any semiconductor layers are deposited. Second, a nucleation layer is grown on the groove walls to prepare the surface for subsequent epitaxial growth. Third, sacrificial layers are deposited on groove walls to control the final groove geometry. These preliminary actions ensure that the high aspect ratio structures are formed with the required precision and that the vertical interfaces between layers are well-defined, enabling high conductivity and fast response.

The patent segments the nitride semiconductor device into distinct functional layers with specific compositions and thicknesses. The structure includes alternating layers of AlGaN (barrier layers) and GaN (channel layers), each with controlled aluminum content and thickness. This segmentation creates multiple vertical heterojunctions that generate 2DEG or 2DHG at each interface. The segmented structure allows independent optimization of each layer's properties to achieve high response speed while managing overall device complexity through systematic design.