The new star of satellite communication -- diamond-based gallium nitride

Currently, GAN-based devices have been widely used in the optoelectronics, radio frequency and automotive fields. However, the advantages of high frequency and high power performance of GAN-based power devices are not given full play because of the problem of heat generation in the source region. The traditional substrate and packaging heat dissipation technology can not solve the bottleneck problem of "heat". Diamond is a kind of wide band gap semiconductor material with excellent performance. As a new thermal management material, diamond has ultra-high thermal conductivity, so it has great application potential in high-frequency and high-power Gan-based high electron mobility transistors (HEMTs) and heat dissipation of circuits, which can effectively reduce the self-heating effect of gallium nitride high-power devices.

There are currently three manufacturing methods:

Figure 1.

GaN & diamond combined takes advantage of the ultra-high thermal conductivity of diamond, which dissipates heat more effectively and efficiently than other materials. In addition, diamond's high breakdown field, high saturation velocity, excellent thermal properties and other characteristics facilitate signal transmission over long distances or at high power levels, which makes GaN & diamond stand out in RF applications. Diamond, with its unique combination of high thermal conductivity, mechanical strength, electrical insulation, low weight and chemical inertness, provides high-frequency active semiconductors with better electrical equipment operation, lower operating temperatures, higher reliability and longer service life, and is therefore considered an excellent material for high power density/high-frequency equipment.

AkashSystems, which specializes in the development and supply of small satellites (Cubesats) as well as RF power amplifiers, recently demonstrated high performance diamond-based GaN transistors (simplified power amplifiers). It shows a 60% power plus efficiency (PAE) at 20GHZ in the K-band (see Figure 2).

Figure 2: A sample device using a 2.9 W (5.6 W/mm)HEMT with a gain of 7.9 dB yielded a PAE of 61% with a bias of 24 V

Akash Systems uses "gradient diamond with low thermal boundary impedance (TBR)" to produce GaN on diamond (green); This curve shows a peak temperature of 152°C (the first peak). The temperature of SiC - based GaN at the same point on the device is 232℃.

Figure 3: Shows the channel center to edge temperature distribution of GaN's 10finger HEMT wafer on different types of diamond

The above two experiments fully prove that diamond-based gallium nitride has sufficient superior characteristics for application in satellite communication field. However, as the first enterprise to carry out GaN&Diamond research, CSMH has made breakthrough progress in the three combination schemes of GaN&Diamond. The existing GaN on Diamond, Diamond on GaN and GaN&Diamond bonding diamond hot sink sheet, benchmarking international first-class. The technical indexes of existing diamond thermal sink sheets and wafer-grade diamond products have reached the world leading level. The surface roughness of diamond  wafer growth surface Ra < 1nm, and the thermal conductivity of diamond heat sink  reaches 1000-2000W/m.K. We will continue to make scientific and technological innovations, strive to be the driver and contributor of scientific and technological progress, and enable cutting-edge technologies to boost the development of relevant applications.