Diamond wafer as the heat dissipation substrate：Enhancing the Performance of GaN RF devices

With the arrival of the 5G era, GaN RF devices have gradually become an important candidate in fields such as communication satellites to meet the needs of high frequency and high power. But this enormous energy can also generate a large amount of heat in the chip area. If this heat cannot be dissipated in time, it will lead to a decrease in the stability and reliability of the device, seriously affecting the performance of the device, and even causing device failure.

Currently, the substrate material for GaN RF devices is mainly SiC. Although SiC material has a high thermal conductivity (350W/m.k.), it still cannot meet the heat dissipation requirements of the device and can only achieve theoretical performance of 20% to 30%. Therefore, improving the heat dissipation capability of GaN RF devices is crucial for further enhancing their power density and conversion efficiency.

Diamond is the material with the highest known thermal conductivity in nature, and it has very stable physical and chemical properties. Diamond has a maximum thermal conductivity of over 2000W/m.k., which is more than 5 times higher than the commonly used substrate material SiC for GaN growth, 13 times higher than Si, and 57 times higher than sapphire. Therefore, diamond is the most ideal substrate material for GaN RF devices.

Currently,there are two main technologies that use diamond as a heat dissipation substrate to solve the heat dissipation problem of GaN RF devices. The first is heterogeneous bonding technology, and the second is direct growth of diamond on GaN technology, which can enable diamond to come into contact with the GaN functional layer as closely as possible and achieve lower interfacial thermal resistance.

Through testing, it has been shown that compared with SiC based GaN HEMT devices, the output power density of diamond based GaN HEMT devices can be increased by nearly 30%. This result indicates that GaN HEMT devices prepared with diamond as the heat dissipation substrate can achieve excellent performance such as high power, high frequency, and ultra-low energy consumption, and have great potential for application in the field of next-generation solid-state microwave power devices.

CSMH uses MPCVD to prepare high-quality diamonds, producing diamond wafer with Ra<1nm and diamond heat sink thermal conductivity of 1000-2000W/m.k. Customers have proven that using CSMH diamond as a substrate material can effectively dissipate heat, reduce overheating risks, and extend the service life of electronic devices.CSMH also has diamond window, single crystal diamond and so on.