This letter presents details of high-performance enhancement-mode GaN MIS high-electron-mobility transistor (MIS-HEMT) devices. Devices with an n-GaN/i-AlN/n-GaN triple cap layer, a recessed-gate structure, and high- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> gate dielectrics show high drain current complete operation. The maximum threshold voltage ( xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub...

This letter reports on an InAlGaN/GaN high-electron-mobility transistor (HEMT) employing a SiC/diamond-bonded heat spreader with record high output power density of 22.3 W/mm. A quaternary In-added InAlGaN barrier enabled both the large current over 1 A/mm and breakdown voltage 257 V. The drain bias was increased as 100 V for S-band load-pull measurement, leading to operation. Furthermore, thermal resistance reduced by 60%, from 18.8 7.2°C/W, SiC/diamond spreader. dissipation effect clearly...

The study reports the findings on a quaternary InAlGaN/GaN high electron mobility transistor (HEMT) employing thermal chemical vapor deposition (TCVD) silicon nitride (SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ) passivation with record output power density of 31.0 W/mm in X-band. We compared two different SiN methods, namely, TCVD deposition, and plasma-enhanced CVD (PECVD) for HEMTs investigated effects device performance....

Herein, the observation of extremely high‐density (&gt;10 14 cm −2 ) 2D electron gas (2DEG) in N‐polar AlGaN/GaN heterostructures grown on sapphire substrates is reported on. Due to introducing GaN/AlN superlattice (SL) back barrier between GaN buffer layer and AlGaN layer, a giant enhancement 2DEG density observed at GaN/AlGaN interface from 3 × 10 13 (without SL) 1.4 (with SL barrier) that only one order magnitude below intrinsic crystal limit ≈10 15 . it found changes with correlated well...

Abstract An AlGaN/GaN high-electron-mobility transistor (HEMT) on a free-standing GaN substrate achieved impressive power-added and drain efficiencies of 85.2% 89.0%, respectively, at 2.45 GHz. We improved the channel quality by reducing C concentration eliminated buffer leakage path removing residual Si substrate-epitaxial layer interface. These improvements, combined with reduction in dislocation density elimination nucleation using substrate, contributed to enhanced efficiency. To best...

Abstract We investigated the impact of In within barriers on gate leakage current in InAlGaN/GaN high-electron-mobility transistors (HEMTs). Results revealed that (In)AlGaN depends solely two-dimensional electron gas density, regardless presence atoms. Furthermore, inclusion atoms reduces tensile strain high-Al-composition barrier, suppressing crack formation. This makes InAlGaN suitable for high-output-power HEMTs with high-Al-content barriers. Moreover, we demonstrate terminating...

GaN-based high-electron-mobility transistors (HEMTs) fabricated on SiC substrates were successfully bonded to single-crystal diamond heat spreader by a surface activated bonding method with thin titanium (Ti) cover layer. A Ti layer the improved strength of SiC/diamond interface since formation an amorphous was suppressed. This process applied high-output power InAlGaN/GaN HEMTs spreaders. The structure reduced thermal resistance devices and enabled their high-power operation.

Abstract In this letter, we successfully achieved high-power radio frequency (RF) operation of AlGaN/GaN high electron mobility transistors (HEMTs) fabricated on free-standing AlN substrate at X-band. The developed HEMT comprised a 200 nm thick GaN channel and AlGaN buffer with an Al composition 30%. Thanks to breakdown voltage the substrate, demonstrated 15.2 W mm −1 output power density operating voltages 70 V even without device technologies such as source-field plate optimization...

In this paper, we report a C-band power amplifier with over 340-W output using 0.8-mum GaN-HEMTs and an X-band 100-W 0.25-mum GaN-HEMTs. We used two-chip configurations the three-stage impedance transformers to extend bandwidth for both circuits. The input lines adjacent each chip are divided by four suppress non-uniform heat distribution in at high frequencies. As result, obtained 343-W 53-% added efficiency (PAE) 4.8 GHz. This is highest ever reported amplifiers. also 101-W PAE 9.8...

This paper reports on the electrical characterization of Ni/Au Schottky diodes fabricated InAlN high-electron-mobility transistor (HEMT) structures grown low dislocation density free-standing GaN substrates. HEMT were sapphire and substrates by metal-organic vapor phase epitaxy, effects threading leakage characteristics investigated. Threading densities determined to be 1.8 × 104 cm−2 1.2 109 cathodoluminescence measurement for substrates, respectively. Leakage compared between two samples,...

This paper investigates the effects of MOVPE growth parameters on gate leakage characteristics InAlN HEMT structures and compares current paths in AlGaN a nanometer scale. The were compared, large was found to result from high-density 2DEG-induced strong electric field accumulation barrier layer. Both increasing rate decreasing temperature InAIN layer caused deterioration surface morphologies. Conductive AFM measurements performed for structures, one-to-one clear correlation between pits...

The gate leakage characteristics of n-GaN- and i-GaN-capped AlGaN/GaN high-electron-mobility transistor (HEMT) heterostructures grown on various substrates Si, SiC, GaN were investigated. HEMT by metal-organic vapor phase epitaxy, the effect n-GaN cap layer doping was investigated depending dislocation densities. For i-GaN capped substrates, current–voltage well explained theoretical calculation based thermionic emission, thermionic-field field emission. Alternatively, for Si that contain a...

We demonstrated the suppression of Fe incorporation into undoped GaN layers grown on an Fe-doped layer by metal organic chemical vapor deposition (MOCVD). Our systematic study depth profile doping secondary-ion mass spectrometry (SIMS) revealed that segregation growth surface is responsible for upper layer. Moreover, we confirmed from profiles strain-varied Al x Ga 1- N compressive strain could effectively suppress segregation. In this study, propose a new model showing due to increase in...

Diamond films were grown on GaN high-electron mobility transistors (HEMTs) to improve thermal dissipation. We observed the temperature reduction in HEMTs using Raman spectroscopy. The large-grain-size (over 1 μm) diamond under 〈110〉 preferential growth condition exhibited a high conductivity of over 200 W m−1 K−1. These films, which at 700 °C, could be directly applied onto HEMT surface thermally stable SiNx metal insulator semiconductor gate structure. maximum and resistance decreased by...

Abstract This study describes high-power and high-efficiency W-band InAlGaN/AlN/GaN high-electron-mobility transistors (HEMTs) for future sub-terahertz wireless communications. A low-thermal-budget selective-area growth (SAG) process was developed to obtain low contact resistance with trap states. Transmission lines substrate structures were optimized high-thermal conductivity resonance. Consequently, a high output power of 28.7 dBm (742 mW), density 4.6 W mm −1 , power-added efficiency...

Abstract This paper describes a technique to improve the drain leakage current and collapse problems with GaN high electron mobility transistors (GaN‐HEMTs) for millimeter‐wave high‐power high‐efficiency amplifiers very short gate‐periphery. To investigate relationships between leakage, crystal quality of an AlGaN buffer structure channel layer, we performed analyses atomic force microscope (AFM) examined photoluminescence (PL), lattice strain electrical characteristics devices. Through...

Abstract GaN monolithic microwave integrated circuits (MMICs) on a diamond heat spreader were successfully fabricated and demonstrated. The was bonded to the back-side surface of SiC devices by atomic diffusion bonding. In addition, through-substrate vias (TSVs) using deep dry etching process. This study marks first development MMIC with TSVs etching. From large-signal measurement MMICs at 7 GHz, output power device during continuous wave operation improved 11% compared that without diamond.

We demonstrated low-sheet-resistance metalorganic-vapor-phase-epitaxy-grown InAlN high-electron-mobility transistors using AlGaN spacers with excellent surface morphology. systematically investigated the effects of spacer growth conditions on morphology and electron mobility. found that barriers depends spacers. Ga desorption from was suppressed by increasing trimethylaluminum (TMA) supply rate, resulting in small roughnesses Moreover, we an increase NH3 rate also improved morphologies as...

To improve the electron mobility of quantum well (QW) gallium nitride (GaN) high transistors (HEMT), we investigated QW and conventional AlGaN/GaN heterostructures grown by metal organic vapor phase epitaxy. Using calculation experimental results, revealed that primary reason for reduced GaN-HEMT is increase in intrasubband scattering events because excessive confinement, which caused a strong polarization electric field. A strained Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML"...

Abstract We demonstrate the advantages of an AlGaN spacer layer in InAlN high-electron-mobility transistor (HEMT). investigated effects growth parameters on electron mobility HEMTs grown by metalorganic vapor phase epitaxy, focusing surface roughness and sharpness interface with GaN channel layer. The degraded, as evidenced formation a graded at top AlN believe that short migration length aluminum atoms is responsible for observed degradation. An was employed to suppress improve morphology....

This article presents the origin of unintentional gallium (Ga) incorporation into AlN spacer layers grown by metalorganic vapor phase epitaxy (MOVPE). We systematically investigated impacts on growth layer caused reactor inner walls condition, under‐layer compositions and temperature. The Ga is not influenced GaN deposits reactor, but strongly affected underlying layer. found that incorporates atoms originate from layer, amount decreases with decreasing conclude dominant source an...

The high-power operation of InAlGaN/GaN high-electron-mobility transistor (HEMT) amplifiers in the wide-frequency range from S-band to W-band has been achieved. A re-grown n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -GaN contact layer and an InGaN back-barrier was employed for GaN HEMT amplifiers. For S-band, 2-dimensional electron gases (2DEG) mobility improved using atomically flat AlGaN spacer layers. This technology allows us...

In this paper, we describe 600 V GaN high electron mobility transistors (HEMTs) technologies on a 6-inch Si substrate using an Au-free Si-LSI mass production line. Metal insulator semiconductor (MIS) HEMTs were fabricated AlN as gate insulator. The layer was deposited by thermal atomic deposition (ALD) method the mass-production-type vertical reactor which capable for over 100 wafer depositions per run. High-temperature breakdown voltage of confirmed. Uniform static on-resistance (R <sub...