Comparison of GaN HEMTs on Diamond and SiC Substrates

Abstract

The performance of AlGaN/GaN high-electronmobility transistors (HEMTs) on diamond and SiC substrates is examined. We demonstrate GaN-on-diamond transistors with periphery W G = 250 µm, exhibiting f t = 27.4 GHz and yielding a power density of 2.79 W/mm at 10 GHz. Additionally, the temperature rise in similar devices on diamond and SiC substrates is reported. To the best of our knowledge, these represent the highest frequency of operation and first-reported thermal and X -band power measurements of GaN-on-diamond HEMTs.Index Terms-GaN on diamond, high-electron-mobility transistor (HEMT), microwave power, thermal effects in AlGaN, X -band.

Control of the in-plane thermal conductivity of ultra-thin nanocrystalline diamond films through the grain and grain boundary properties

“…Recently, the integration of diamond with high power AlGaN/GaN high mobility electron devices (HEMTs) was demonstrated to be a very promising solution to optimize their heat management, [1,2,3,4,5,6,7,8,9, 10] which enables handling much higher operational electrical power densities. [1] To take 5 full advantage of the high thermal conductivity of diamond, reaching up to 3000 W/mK for single crystalline high quality diamond, the diamond heat dissipation layer should be located as close as possible to the heat source, ie the device channel.…”

“…[1] To take 5 full advantage of the high thermal conductivity of diamond, reaching up to 3000 W/mK for single crystalline high quality diamond, the diamond heat dissipation layer should be located as close as possible to the heat source, ie the device channel. [4,8] This is achieved by directly growing diamond films on the devices, which results in polycrystalline diamond films rather than single crystal 10 diamond.…”

“…However, while the thermal conductivity of polycrystalline diamond may reach values close to that of the single crystal diamond, [11] the thermal transport near its near nucleation site may be much lower due the small grain size and the accumulation of defects in this region. [12,13] Two strategies for combining diamond with the devices using the direct growth approach have 15 emerged in the recent years, , namely, either by substituting the SiC or Si substrate, [1,3,4,5] or by growing the diamond films on top of the device passivation layer. [6,7,8,9, 10] However, in both strategies the heat has to diffuse across the nucleation region of the diamond film, and therefore knowing how the heat is spread in the first microns of the polycrystalline diamond is fundamental 20 in order to optimize their thermal resistance and thus improve their lifetime and reduce its energy consumption.…”

The world’s first high voltage GaN-on-Diamond power semiconductor devices

“…This area of research is gaining focus and reports evaluating integration of Diamond and GaN for device technologies have been published [4,5]. It has already been shown through simulation and experimental demonstration that GaN-on-Diamond platform can significantly outperform GaN-on-SiC platform for Radio Frequency (RF) applications by reducing thermal resistance and thereby increasing power density [3,6,7]. Fig.…”

GaN grown on (111) single crystal diamond substrate by molecular beam epitaxy

“…Indeed, even a few nanometers thick layer behaves as a thermal barrier. While promising this hybrid approach still has to demonstrate higher performance devices than standard GaN based HEMTs grown on SiC substrate [6].…”