Gan on Sapphire Wafer：

Particularly in high-voltage applications, such as those requiring vertical GaN devices with ratings more than 600 V, vertical GaN power devices have the potential to transform the power device market. GaN devices have a lower on-resistance at a given breakdown voltage compared to both classic silicon-based power devices and upcoming pure silicon carbide power devices, depending on the material’s physical features. In the low-voltage market, horizontal GaN power devices, also known as GaN-on-Silicon high mobility transistors (HEMTs), compete with silicon devices, and GaN is superior, further demonstrating the superiority of GaN materials.
To compete in the high-voltage market with pure silicon carbide power devices, vertical GaN power devices are being developed. A number of businesses have increased production of 6-inch and 8-inch SiC in the first two years, and SiC devices have earned some market share in the high-voltage application sector. On the other hand, vertical GaN devices are not yet on the market, and only a select few manufacturers can produce GaN wafers with a 4-inch diameter. For vertical GaN devices to advance, it is essential to increase the availability of high-quality GaN wafers.
Gallium nitride high voltage power devices may offer three benefits:
The predicted on-resistance is much lower than the experimental one under a fixed breakdown voltage. That’s why the forward bias power loss is lower and the overall energy efficiency is better.

Second, the manufactured device is smaller in size given a specific breakdown voltage and on-resistance. More devices can be manufactured at once from a single wafer if the devices are smaller in size. Moreover, most uses necessitate a reduced chip size.

Finally, the material properties and device design decide the highest operating frequency of the device, where gallium nitride has an advantage. When compared to power devices built of gallium nitride, which can operate at frequencies in the tens of megahertz, silicon carbide is often limited to frequencies of 1 MHz or less. The size, weight, and cost of the power conversion system can be decreased by operating at higher frequencies since the passive components can be made smaller.
The industry has not yet agreed on the best design for a vertical GaN power device, and the technology is still in the early stages of development. The three most common types of transistors are the Current Aperture Vertical Electron Transistor (CAVET), the Trench Field Effect Transistor (Trench FET), and the Fin Field Effect Transistor (Fin FET). A low N-doped layer serves as the drift layer in all device architectures. The breakdown voltage of the device is dependent on the thickness of the drift layer, which is provided by this layer. Moreover, the electron concentration is important for obtaining the theoretically lowest on-resistance. role that is crucial in the context.