Integration of chemical vapor deposited polycrystalline diamond offers promising thermal performance for GaN-based high power radio frequency amplifiers. One limiting factor is the barrier at GaN to interface, often referred as effective boundary resistance (TBReff). Using a combination transient thermoreflectance measurement, finite element modeling and microstructural analysis, TBReff GaN-on-diamond wafers shown be dominated by SiNx interlayer growth seeding, with additional impacts from...

The performance of AlGaN/GaN high-electron-mobility transistors (HEMTs) on diamond and SiC substrates is examined. We demonstrate GaN-on-diamond with periphery <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">WG</i> = 250 mum, exhibiting xmlns:xlink="http://www.w3.org/1999/xlink">ft</i> 27.4 GHz yielding a power density 2.79 W/mm at 10 GHz. Additionally, the temperature rise in similar devices reported. To best our knowledge, these represent...

High-power operation of AlGaN/GaN high-electron-mobility transistors (HEMTs) requires efficient heat removal through the substrate. GaN composite substrates, including high-thermal-conductivity diamond, are promising, but high thermal resistances at interfaces between and diamond can offset benefit a We report on measurements GaN-diamond for two generations (first second) GaN-on-diamond using combination picosecond time-domain thermoreflectance (TDTR) nanosecond transient techniques. Two...

The integration of strongly contrasting materials can enable performance benefits for semiconductor devices. One example is composite substrates gallium nitride (GaN) and diamond, which promise dramatically improved conduction cooling high-power GaN transistors. Here, we examine phonon in GaN-diamond fabricated using a epilayer transfer process through transmission electron microscopy, measurements time-domain thermoreflectance, semiclassical transport theory phonons interacting with...

Record DC power has been demonstrated in AlGaN/GaN high electron mobility transistors fabricated using a substrate replacement process which thick diamond is grown by chemical vapor deposition following removal of the original Si substrate. Crucial to ~30 nm SiN interlayer that optimized for thermal resistance. The reductions obtained self-heating have quantified transient thermoreflectance imaging and interpreted 3D numerical simulation. With dissipation level 56 W/mm, measured average...

The thermal properties of GaN-on-diamond high-electron mobility transistor (HEMT) wafers from 25 °C to 250 are reported. effective boundary resistance between GaN and diamond decreases at elevated temperatures due the increasing conductivity amorphous SiNx interlayer, therefore potentially counteracting runaway devices. results demonstrate benefit for HEMT high-power operations, provide valuable information assessing reliability

Record RF performance of AlGaN/GaN high electron mobility transistors (HEMTs) on a diamond substrate with over 7 W/mm output power density at 10 GHz is reported. It achieved along the peak power‐added‐efficiency 46% and gain 11 dB for 2 × 100 µm gate‐width HEMTs 40 V drain bias. Device wafers are prepared by first removing host Si (111) nitride transition layers beneath channel, depositing 50 nm dielectric onto exposed GaN buffer, finally growing chemical vapour deposition adhering to...

Thermal conductivity of the substrate affects performance high power RF devices. It is a dominant limiting factor in current state-of- the-art GaN HEMTs on SiC substrate. Due to thermal conductivity, diamond an attractive alternative for HEMTs. We have developed device quality GaN-on-diamond wafers using CVD and fabricated 0.25 μm gate length present detailed electrical results devices, which show comparable standard GaN-on-SiC demonstrate over 25 % lower channel temperature these devices...

Gallium nitride (GaN) high electron-mobility transistors (HEMTs) offer considerable high-power operation but suffer in reliability due to potentially damaging self-heating. In this study, self-heating AlGaN/GaN HEMTs on conductivity substrates is assessed using a high-resolution thermoreflectance (TR) imaging technique, compare the thermal response between GaN-on-Si, GaNon-Diamond, and GaN-on-4H-SiC. The TR method accuracy at density verified nonlinear coefficient of (CTR) as function...

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We report on electrical characterization and uniformity measurements of the first conventionally processed AlGaN/GaN high electron mobility transistors (HEMTs) free-standing chemical-vapor-deposited (CVD) diamond substrate wafers. DC RF device performance is reported HEMTs fabricated <formula formulatype="inline"><tex Notation="TeX"> $\sim\!\!\hbox{130-}\mu\hbox{m}$</tex></formula>-thick 30-mm...

Low thermal resistance GaN-on-diamond wafers offer enhanced management with respect to GaN-on-SiC devices. The GaN/diamond interfacial can contribute significantly the total device and must therefore be minimized gain maximum benefit from GaN-on-diamond. A contactless thermoreflectance measurement technique has been developed, which used after wafer growth before fabrication, enabling rapid feedback about influence of parameters on resistance. measured 2× reduction in is achieved by reducing...

The emergence of Gallium Nitride-based High Electron Mobility Transistor (HEMT) technology has proven to be a significant enabler next generation RF systems. However, thermal considerations currently prevent exploitation the full electromagnetic potential GaN in most applications, limiting HEMT areal power density (W/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) small fraction electrically limited performance. on Diamond been...

This letter is a first report on the operation of AlGaN/GaN high-electron mobility transistors (HEMTs) atomically attached to CVD diamond substrate. technology demonstration shows feasibility producing GaN based devices polycrystalline substrates maximize heat extraction from operating at high power by situating in immediate proximity transistor channel. Such an approach offers tremendous opportunity for efficient and effective management devices. We demonstrate ability preserve electrical...

The performance of an AlGaN/GaN high electron mobility transistor (HEMT) on diamond substrate is reported. Presented a device with gate footprint LG=40 nm and periphery WG=100 µm that exhibits fT=85 GHz fmax=95 GHz. It believed this represents the best frequency GaN-on-diamond HEMT.

The mechanical and thermo-mechanical integrity of GaN-on-diamond wafers used for ultra-high power microwave electronic devices was studied using a micro-pillar based in situ testing approach combined with an optical investigation the stress heat transfer across interfaces. We find GaN/diamond interface to be thermo-mechanically stable, illustrating potential this material reliable GaN devices.

This paper describes the thermal and electrical performance of GaN on Diamond devices, where substrates are fabricated by taking epi from a host growth substrate replacing it through direct CVD diamond. We have found material improves while maintaining performance. work demonstrates that technology can form foundation next generation device with 3X (or more) higher areal power density.

The performance of high-power gallium nitride (GaN) high-electron-mobility transistors (HEMTs) is limited by self-heating effects. High thermal resistances within micrometers the active device junction often dominate temperature rise and fundamentally limit power handling capability. use high-thermal-conductivity diamond in close proximity to transistor can mitigate this constraint, but careful attention required quality interface between GaN diamond. Here we apply time-domain...

Reliable operation of high power GaN amplifiers at maximum performance relies on the mutual optimization several design parameters constrained by a defined thermal budget. On conductivity, substrates, such as SiC and diamond, undergo small changes within that can lead to drastic in channel temperature. We utilize finite element simulations provide rules for device structures GaN-on-diamond amplifiers, benchmarked against GaN-on-SiC. At 8 W/mm density, 13 μm gate pitch compared commonly...

High-power operation of AlGaN/GaN high-electron-mobility transistors (HEMTs) requires efficient heat removal through the substrate. GaN composite substrates including high-thermal-conductivity diamond are promising, but high thermal resistances at interfaces between and can offset benefit a We report on measurements GaN-diamond for two generations (1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> 2...

This paper chronicles the historical technical development of Gallium Nitride-on-Diamond wafers and transistor devices by authors starting from 2003 until current status in 2014. is not exhaustive scope; selected accounts have been omitted either inadvertently or to maintain brevity.

GaN thin film integrated to polycrystalline diamond substrates is a novel microwave transistor material with significantly improved heat dissipation capability. Due the thermal and mechanical properties mismatch between diamond, natural concern arises in terms of its interfacial stability as currently there no established method evaluate toughness GaN-on-diamond material. Using three generations "GaN-on-Diamond" materials varying process parameters, comprehensive study has been carried out...

Ultraviolet (UV) micro-Raman measurements are reported of diamond grown on GaN using chemical vapor deposition. UV excitation permits simultaneous investigation the (D) and disordered carbon (DC) comprising polycrystalline layer. From line scans a cross-section along growth direction, DC component layer is found to be highest near GaN-on-diamond interface diminish with characteristic length scale ∼3.5 μm. Transmission electron microscopy (TEM) confirms presence DC. Combined TEM used develop...