Wide Bandgap Materials Research Articles

Electron–phonon effects and temperature-dependence of the electronic structure of monoclinic β-Ga2O3

Gallium oxide (Ga2O3) is a promising semiconductor for next-generation high-power electronics due to its ultra-wide bandgap and high critical breakdown field. To utilize its unique electrical properties for real-world applications, an accurate description of its electronic structure under device-operating conditions is required. Although the majority of first-principles models focus on the ground state, temperature effects govern the key properties of all semiconductors, including carrier mobility, band edge positions, and optical absorption in indirect gap materials. We report on the temperature-dependent electronic band structure of β-Ga2O3 in a wide temperature range from T = 0 to 900 K using first-principles simulations and optical measurements. Band edge shifts from lattice thermal expansion and phonon-induced lattice vibrations known as electron–phonon renormalization are evaluated by utilizing the quasi-harmonic approximation and the recently developed “one-shot” frozen phonon method, respectively. Electron–phonon effects and thermal expansion together induce a substantial temperature-dependence on the bandgap, reducing it by more than 0.5 eV between T = 0 and 900 K, larger than that observed in other wide bandgap materials. Key implications, including an increase in carrier concentrations, a reduction in carrier mobilities due to localization of band edge states, and an ∼20% reduction in the critical breakdown field, are discussed. Our prediction of temperature-dependent bandgap matches very well with experimental measurements and highlights the importance of accounting for such effects in first-principles simulations of wide bandgap semiconductors.

Two-dimensional AlN/TMO van der Waals heterojunction as a promising photocatalyst for water splitting driven by visible light.

In this study, the photocatalytic properties of AlN/TMO heterojunctions formed by coupling MoO2 and WO2 of transition metal oxides with AlN are studied in detail using first-principles calculations with the aim of finding efficient and low-cost photocatalysts for water splitting to produce hydrogen to reduce environmental pollution. The AIMD, phonon spectrum, and elastic constants demonstrated the thermodynamic, kinetic, and mechanical stabilities of the AlN/TMO heterojunction. The results showed that the AlN/MoO2 (1.55 eV) and AlN/WO2 (1.99 eV) heterojunctions have typical type-II energy band arrangements, which can effectively promote the separation of photogenerated electrons and hole pairs. Meanwhile, the AlN/MoO2 heterojunction showed excellent carrier mobilities (electron, 250.05 cm2 V-1 S-1 and hole, 45 467.07 cm2 V-1 S-1), which greatly exceeded those of each component. The AlN/WO2 heterojunction showed an excellent HER (-0.07 eV) performance, which was close to the expected value. For the AlN/WO2 heterojunction, a suitable band gap value, excellent HER, and other properties indicated that it has the potential to become a new candidate for photocatalytic water splitting. Our study enriches the theoretical research of transition metal oxide materials and wide-band gap materials by providing a reference direction for the design of reasonably high-quality photocatalysts.

Performance of neutron-irradiated 4H-silicon carbide diodes subjected to alpha radiation

The unique electrical and material properties of 4H-silicon-carbide (4H-SiC) make it a promising candidate material for high rate particle detectors. In contrast to the ubiquitously used silicon (Si), 4H-SiC offers a higher carrier saturation velocity and larger breakdown voltage, enabling a high intrinsic time resolution and mitigating pile-up effects. Additionally, as radiation hardness requirements grow more demanding in the context of future high luminosity high energy physics experiments, wide-bandgap materials such as 4H-SiC could offer better performance due to low dark currents and higher atomic displacement thresholds. In this work, the detector performance of 50 µm thick 4H-SiC p-in-n planar pad sensors was investigated at room temperature, using an 241Am alpha source at reverse biases of up to 1100 V. Samples subjected to neutron irradiation with fluences of up to 1 × 1016 neq/cm2 were included in the study in order to quantify the radiation hardness properties of 4H-SiC. A calibration of the absolute number of collected charges was performed using a GATE simulation. The obtained results are compared to previously performed UV transient current technique (TCT) studies. Samples exhibit a drop in charge collection efficiency (CCE) with increasing irradiation fluence, partially compensated at high reverse bias voltages far above full depletion voltage. At fluences of 5 × 1014 neq/cm2 and 1 × 1015 neq/cm2, CCEs of 64 % and 51 % are obtained, decreasing to 15 % at 5 × 1015 neq/cm2. A plateau of the collected charges is observed in accordance with the depletion of the volume the alpha particles penetrate for an unirradiated reference detector. For the neutron-irradiated samples, such a plateau only becomes apparent at higher reverse bias, roughly 600 V and 900 V for neutron fluences of 5 × 1014 neq/cm2 and 1 × 1015 neq/cm2. For the highest investigated fluence, CCE behaves almost linearly with increasing reverse bias. Compared to UV-TCT measurements, the reverse bias required to deplete a sensitive volume covering full energy deposition is lower, due to the small penetration depth of the alpha particles. At the highest reverse bias, the measured CCE values agree well with earlier UV-TCT studies, with discrepancies between 1% and 5%.

Effect of Single Atom Doping on Structural, Electronic and Magnetic Properties of Hexagonal Silicon Carbide (4H-SiC) for Spintronic Application: A first principle study

In this paper, the structural geometry, electronic and magnetic properties of single magnesium (Mg) and vanadium (V) atoms doped 4H-SiC system were investigated. For the structural geometry of each sample, the energy substitution, as well as bond length, were calculated; results obtained indicate that the bond length of Silicon-Magnesium (Si-Mg) and SiliconVanadium (Si-V) was 1.90 Å and 2.02 Å respectively, greater than that of silicon-carbon (SiC) 1.89 Å in pure SiC. This result indicates that the bond length increases due to the introduction of dopants with greater radii than that of Si. It also shows that both Mg and V doping change the structure from non-magnetic ordering to magnetic in nature. The band structure result for both undoped and doped shows the presence of valence band maximum (VBM) and conduction band minimum (CBM) around different symmetry points which indicate an indirect band gap nature. The calculated band gap of pure 4H SiC is found to be ~2.21 eV, which is at a wide band gap material range, but with the introduction of Mg and V dopants, the band gap reduced significantly to ~0.4 eV and ~0.45 eV respectively. The density of state (DOS) and projected density of state (PDOS) show the contributions of the various states in both the VBM and CBM; after doping the Fermi energy is shifted towards higher energy and enters into the conduction band, exhibiting spin polarization. Both DOS and PDOS indicated that the magnetic moments mainly come from the 2p orbitals of Si atoms and 3p for Mg dopant and 3d orbitals for V dopant. The magnetic moment for 4H-SiC/Mg and 4H-SiC/V was calculated to be 2.23 μB and 3.24 μB.

Experimental evidence for large negative electron affinity from scandium-terminated diamond

Two Sc–diamond (100) and (111) surfaces have the highest negative electron affinity for a metal adsorbed onto bare diamond measured to date, as well as being thermally stable up to 900 °C.

SbSeI and SbSeBr micro-columnar solar cells by a novel high pressure-based synthesis process.

Van der Waals chalcogenides and chalcohalides have the potential to become the next thin film PV breakthrough, owing to the earth-abundancy and non-toxicity of their components, and their stability, high absorption coefficient and quasi-1D structure, which leads to enhanced electrical anisotropic properties when the material is oriented in a specific crystalline direction. However, quasi-1D semiconductors beyond Sb2(S,Se)3, such as SbSeX chalcohalides, have been scarcely investigated for energy generation applications, and rarely synthesised by physical vapor deposition methodologies, despite holding the promise of widening the bandgap range (opening the door to tandem or semi-transparent devices), and showing enticing new properties such as ferroelectric behaviour and defect-tolerant nature. In this work, SbSeI and SbSeBr micro-columnar solar cells have been obtained for the first time by an innovative methodology based on the selective halogenation of Sb2Se3 thin films at pressure above 1 atm. It is shown that by increasing the annealing temperature and pressure, the height and density of the micro-columnar structures grows monotonically, resulting in SbSeI single-crystal columns up to 30 μm, and tuneable morphology. In addition, solar cell prototypes with substrate configuration have shown remarkable Voc values above 550 mV and 1.8 eV bandgap.

Photoelectrochemical assay based on CRISPR/Cas12a coupled with AuNP/MoS2/WS2/g-C3N4 nanoprobe for determination of hepatitis B virus

A nanoprobe photoelectrochemical (PEC) assay combined with CRISPR/Cas12a was explored to detect nucleic acid. Ternary heterojunctions, nanoflower MoS2/WS2/g-C3N4, were synthesized by hydrothermal method. The narrow band gap materials MoS2, WS2 and the wide band gap material g-C3N4 were composited to obtain ternary heterojunction nanoflowers with high photoelectric response. The gold nanoparticles (AuNPs) in situ grown on MoS2/WS2/g-C3N4 and incubated with signal DNA got PEC nanoprobe, signal DNA/AuNP/MoS2/WS2/g-C3N4. The electrode was modified with electrodeposited AuNPs producing background signal. In the presence of target, catalytic hairpin assembly was activated and target was recycled, and this process activated the activity of the Cas12a enzymes and completed the cleavage. The cleavaged double DNA was linked with capture DNA and nanoprobe, generating PEC signal on AuNPs modified electrode no needing of any electron donor or acceptor. The results showed that the nanoprobe PEC assay to detect target DNA presented a linear detection range from 1 aM to 1 fM with a detection limit of 0.25 aM (S/N = 3). The PEC assay not only presented a high sensitivity and selectivity, but also provided a different pattern for the detection of other nucleic acids.

High performance foreign-dopant-free ZnO/AlxGa1−xN ultraviolet phototransistors using atomic-layer-deposited ZnO emitter layer

High-performance foreign-dopant-free ZnO/AlxGa1−xN heterojunction ultraviolet (UV) phototransistors were fabricated and characterized. The ZnO layer with high electron concentration was grown as emitter by atomic layer deposition, while the AlxGa1−xN/GaN heterostructure was epitaxied as base and collector by metal organic chemical vapor deposition. A linearly upgraded/downgraded AlxGa1−xN layer was used as polarization-induced n/p type layer without dopant. The prominent feature of the resulting n+-p-n ZnO/AlxGa1−xN phototransistors is a three-stage rising spectral response matching the biological action spectrum of solar UV radiation. Moreover, the phototransistors demonstrate a low dark current of less than 1 pA at 2 V, a maximum responsivity of ∼8.7 A/W at 5 V and 300 nm, a normalized detectivity of ∼1 × 1013 Jones, and a high response speed with a rise/fall time of 3.5 μs/450 μs. This work shows a feasible and simple-process approach for developing high-performance multiband spectral response photodetectors based on different wide band gap material systems.

A review of thermoreflectance techniques for characterizing wide bandgap semiconductors’ thermal properties and devices’ temperatures

Thermoreflectance-based techniques, such as pump–probe thermoreflectance (pump–probe TR) and thermoreflectance thermal imaging (TTI), have emerged as the powerful and versatile tools for the characterization of wide bandgap (WBG) and ultrawide bandgap (UWBG) semiconductor thermal transport properties and device temperatures, respectively. This Review begins with the basic principles and standard implementations of pump–probe TR and TTI techniques, illustrating that when analyzing WBG and UWBG materials or devices with pump–probe TR or TTI, a metal thin-film layer is often required. Due to the transparency of the semiconductor layers to light sources with sub-bandgap energies, these measurements directly on semiconductors with bandgaps larger than 3 eV remain challenging. This Review then summarizes the general applications of pump–probe TR and TTI techniques for characterizing WBG and UWBG materials and devices where thin metals are utilized, followed by introducing more advanced approaches to conventional pump–probe TR and TTI methods, which achieve the direct characterizations of thermal properties on GaN-based materials and the channel temperature on GaN-based devices without the use of thin-film metals. Discussions on these techniques show that they provide more accurate results and rapid feedback and would ideally be used as a monitoring tool during manufacturing. Finally, this Review concludes with a summary that discusses the current limitations and proposes some directions for future development.

Electron effective masses of ScxAl1−xN and AlxGa1−xN from first-principles calculations of unfolded band structure

The electron effective masses of ScxAl1−xN and AlxGa1−xN, two of the most promising wide bandgap materials for power and RF electronic applications, have been calculated using the predictions of the density functional theory (DFT). More specifically, the unfolding technique has been adopted to extract the effective band structure of the two alloys under investigation. It has been found that the AlGaN effective masses m∗ approximately follow the Vegard law. On the contrary, due to the larger amount of disorder inside the crystal, the ScAlN shows a non-monotonic change of m∗ as a function of the Sc concentration, which requires the DFT calculations to be consistently performed for an accurate prediction. The ScAlN effective masses as a function of Sc content have been reported in the range 0≤x≤0.25 for the first time.

Wide Band Gap Devices and Their Application in Power Electronics

Power electronic systems have a great impact on modern society. Their applications target a more sustainable future by minimizing the negative impacts of industrialization on the environment, such as global warming effects and greenhouse gas emission. Power devices based on wide band gap (WBG) material have the potential to deliver a paradigm shift in regard to energy efficiency and working with respect to the devices based on mature silicon (Si). Gallium nitride (GaN) and silicon carbide (SiC) have been treated as one of the most promising WBG materials that allow the performance limits of matured Si switching devices to be significantly exceeded. WBG-based power devices enable fast switching with lower power losses at higher switching frequency and hence, allow the development of high power density and high efficiency power converters. This paper reviews popular SiC and GaN power devices, discusses the associated merits and challenges, and finally their applications in power electronics.

Impact of electron-phonon interactions on phonon transport in diamond and c-BN

Diamond and cubic polymorph of boron nitride (c-BN) are two promising next-generation ultrawide bandgap semiconductor materials owning superior thermal properties. Although lattice vibration is the dominant mechanism of heat conduction in semiconductors, electron-phonon interactions exist and may affect phonon transport in doped semiconductors; yet such effects in wide bandgap materials have not received much attention. In this study, we explore the effects of electron-phonon interactions on the lattice thermal conductivity and phonon transport in electron-doped Si, diamond, and c-BN under various electron concentrations and in a wide temperature range from 300 K to 900 K based on the first-principles calculation. It is found that the electron-phonon interactions will bring down the thermal conductivity of doped materials, and the depletion impact increases as the electron concentration increases but decreases as the temperature increases. This depression effect in ultrawide bandgap diamond and c-BN is apparent, though it is not as severe as in Si. At room temperature with a high electron concentration of 10 21 cm −3 , the reduction of thermal conductivity reaches 36 % in Si, and 17.4 % and 16.1 % in diamond and c-BN, respectively. • Thermal effect of electron-phonon interactions in doped c-BN and diamond is revealed. • Temperature and electron concentration dependent lattice thermal conductivity is quantified. • Thermal depletions exist in doped c-BN and diamond, but not as severe as in doped Si. • Depletion lessens as temperature rises, but increases with increasing electron concentration. • Ultrawide bandgap materials have great potentials in high-power high-temperature electronics.

Quantum Emitters in Hexagonal Boron Nitride.

Hexagonal boron nitride (hBN) has emerged as a fascinating platform to explore quantum emitters and their applications. Beyond being a wide-bandgap material, it is also a van der Waals crystal, enabling direct exfoliation of atomically thin layers─a combination which offers unique advantages over bulk, 3D crystals. In this Mini Review we discuss the unique properties of hBN quantum emitters and highlight progress toward their future implementation in practical devices. We focus on engineering and integration of the emitters with scalable photonic resonators. We also highlight recently discovered spin defects in hBN and discuss their potential utility for quantum sensing. All in all, hBN has become a front runner in explorations of solid-state quantum science with promising future prospects.

Tetraphenylsilane-based oligo(azomethine)s containing 3,4-ethylenedioxythiophene units along their backbone: Optical, electronic, thermal properties and computational simulations

A series of three new oligo-poly(azomethine)s (o-PAzMs) were successfully synthesized, incorporating tetraphenylsilane (TPS) and 3,4-ethylenedioxythiophene (EDOT) moieties with Mn and Mw between 3.9 and 5.4 kDa and 8.3–11.6 kDa, respectively. The silylated o-PAzMs were highly soluble in low-boiling point solvents such as CHCl3, THF, and CH2Cl2. All three materials are highly thermally stable, with onset temperatures of degradation of at least 250 °C and with TDT10% between 340 and 460 °C. The glass transition temperature values agree with the flexibility of the repetitive units and showed values between 125 and 155 °C. The absorption and emission of the o-PAzMs were observed in the blue-violet UV–vis region (350–550 nm) with moderate Stokes shifts (48–71 nm). The oligomers are π-conjugated wide-band gap materials (2.83–2.73 eV), where the high electronic transitions would be associated with disruption of π-conjugation, which is promoted by the TPS core and (d-p)π orbital interactions. This disruption controls the effect from the EDOT unit rich donor on HOMO (−5.79 eV to −5.71 eV) and LUMO (−2.98 eV to −2.89 eV) energy values. Furthermore, DFT and TDDFT calculations were performed to theoretically characterize the observed UV–Vis transitions and frontier molecular orbitals (MOs) energies.

Detection of Low-Penetrating Ions in Diamond at Room Temperature

Single-ion implantation as a technique for fabricating future quantum devices requires high precision in placing individual ions in the semiconductor material. One way to achieve this precision is to use focused ion beams and verify the implantation of each ion by detecting the charge it induces in the semiconductor. This method has already been demonstrated for silicon substrates but has yet to be successfully performed for wide-bandgap materials. One of the most promising materials for future quantum devices is a diamond. Quantum centers in diamond, such as nitrogen vacancies, can serve as information carriers in quantum computers—qubits—and are stable at room temperature. This work focuses on understanding the critical parameters required for the successful detection of shallow, low-energy ions in diamonds using commercially available diamond crystals and front-end electronics. Depth profiling of the electric field in the diamond crystal was performed using ions of different species and energy. State-of-the-art front-end electronics were also used to achieve high energy resolution. Using the XGLab CUBE PRE031 preamplifier, an energy resolution of 6 keV was achieved for the detection of 400-keV protons. Detection of 140-keV copper ions, penetrating an average of 100 nm into the diamond, was also demonstrated. The optimal position of implantation sites was determined from the spatial distribution of charge collection efficiency.

Investigation of nanostructured SrNb2SnO8 functional material for opto electronic systems and solid oxide fuel cells

The niobium based oxide materials have good applications in optoelectronic devices due to its significant optical and electrical properties. The sample SrNb2SnO8 is prepared using auto ignition combustion technique. The structure and morphology of the sample are studied using the X-ray diffraction technique and TEM method. XRD analysis shows that sample is crystallizes in tetragonal structure with crystallite size 31 nm. Hall Williamson plot is plotted to confirm the nanocrytalline nature of the sample and also the strain broadening of the particles. Structure is further verified by analyzing the FT-Raman Spectrum of the sample. Optical studies show that it is a wide band gap material with bandgap energy 3.82 eV. The sample is transparent in UV–Visible region and highly reflective in near-infrared region of wavelength. It has strong emission lines in the visible region so that the developed material is a luminar material. Impedance spectroscopic studies give the evidence to the conducting nature of the sample with rise in temperature due to the thermally activated ions. The developed sample, SrNb2SnO8 is found to be a functional material which is suitable for solid oxide fuel cells as an electrolyte due to the ionic conductivity at high temperatures and for opto electronic systems due to its better optical properties.

Dopant‐free passivating contacts for crystalline silicon solar cells: Progress and prospects

AbstractThe evolution of the contact scheme has driven the technology revolution of crystalline silicon (c‐Si) solar cells. The state‐of‐the‐art high‐efficiency c‐Si solar cells such as silicon heterojunction (SHJ) and tunnel oxide passivated contact (TOPCon) solar cells are featured with passivating contacts based on doped Si thin films, which induce parasitic optical absorption loss and require capital‐intensive deposition processes involving flammable and toxic gasses. A promising solution to tackle this problem is to employ dopant‐free passivating contact, involving the use of transparent and cost‐effective wide band gap materials. In this review, we first introduce the dopant‐free passivating contact, from carrier transport mechanisms, material classification to evaluation methods. Then we focus on the advances in different strategies to improve cell performance, including material property optimization, structural and interfacial engineering, as well as various post‐treatments. At the end, the challenge and perspective of dopant‐free passivating contact c‐Si solar cells are discussed.image

Development of “Tunable” Gallium Nitride (GaN) Chemical Mechanical Planarization (CMP) Slurry Formulations

Wide band gap (WBG) semiconductors have become of great interest in order to extend Moore’s Law beyond the limitations of current Si IC technology. WBG material, more specifically gallium nitride (GaN), is known to operate at greater switching speeds, temperatures, and frequencies leading to enhanced processing performance. However, as a result of its chemical properties, GaN is chemically inert impeding the ability to effectively planarize the surface at low chemical mechanical planarization (CMP) processing time and with minimized defectivity. It is widely reported that material removal on the Ga-face of the substrate is highly dependent on the oxidation of the surface to form Ga2O3. This work will focus on exploiting the surface oxidation mechanism of GaN in a low-shear force environment. By modulating the slurry composition (i.e., nanoparticle, oxidizer, redox-active additives), the factors that drive removal rate can be further understood in order to develop an optimized slurry-substrate environment that will promote greater material removal. To evaluate the reactions at the slurry-substrate interface and probe at the removal rate mechanism, a suite of dynamic analytical techniques (i.e., atomic force microscope, scanning electron microscope, profilometer, contact angle, zeta potential, and particle size) will be utilized.

(Invited) Ultrafast Charge Recombination and Localisation in Transition Metal Oxides with Extended Visible Light Absorption

The development of materials with high activity for photocatalytic water splitting is a central challenge for the production of renewable hydrogen using sunlight. Owing to advantages such as low cost, elemental abundance, and chemical stability, transition metal oxides (TMOs) are some of the most widely used materials for this purpose. The most efficient systems developed to date reach solar-to-hydrogen conversion efficiencies (STH) of around 1%1 and are based on wide bandgap TMOs such as SrTiO3.2 Because such wide bandgap materials often absorb UV light only, TMOs with extended visible light absorption are key to bridge the activity gap towards the target for commercial applications,3 often considered to be 10% STH.While large research efforts have been devoted to TMOs with smaller bandgaps, efficiencies for such materials have typically remained relatively far from their theoretical limit. For example, Fe2O3 is one of the most studied TMOs in the field of solar fuel production, but it has so far reached only 1/3 of its theoretical maximum activity for water oxidation,4 raising the question of limitations of more fundamental nature.In this talk, I will discuss the links between ultrafast charge recombination and polaron formation in TMOs – two of the main processes considered to impose efficiency limitations. Firstly, Fe2O3, Cr2O3, and Co3O4, which have absorption onsets of around 2.1 eV, 1.9 eV, and 1.6 eV, respectively, are studied using time-resolved optical spectroscopic techniques to probe their excited state dynamics on a timescale of femtoseconds to seconds following light absorption. I will demonstrate how common photophysical features and dynamics suggest a shared pathway for the recombination and localisation of photogenerated charges in these materials, but with different branching ratios. Secondly, a comparison to wide bandgap metal oxides reveals a different relative importance of these recombination and localisation pathways compared to TMOs with smaller bandgaps. Taken together, a more general photophysical model emerges, providing insights into the performance limiting factors in TMOs, including those with extended visible light absorption.

Integrating Diamond for Cooling Electronics

III-Nitrides promise to offer high-frequency power amplifiers at higher power densities. This is attractive for realizing device platforms for 5G and beyond. It also enables integrating Si-based electronics to complement functionalities. However, to obtain the full potential of III-Nitrides one must operate these transistors at higher power densities, for which thermal management is crucial.Due to the continuous need for higher performance in various applications ranging from DC to W-band frequencies, semiconductor devices are pushed to higher power densities. This results in a higher junction temperature owing to the Joule heating in the channel resulting in device performance degradation and premature failure. Using devices based on wide-bandgap (WBG) semiconductors such as Gallium Nitride (GaN) and Gallium Oxide (GaOx) with a larger critical electric field and high-temperature tolerance, one could increase the power density. However, in order to increase the output power to the levels that is promised by these wide bandgap materials, junction temperature reduction through device-level cooling is critical. We are actively researching thermal management at device, circuit and packaging level using synthetic polycrystalline (PC) diamond. PC-diamond, at an appropriate grain size offers a TC is higher than any competing thermal vias with metals without interfering the electrical performance. Over the past 5 years we have demonstrated the potential of integrating diamond with GaN and recently achieving a record low diamond/GaN thermal boundary resistance (TBR) along with a relatively high diamond thermal conductivity (TC). This remarkable thermal performance was be achieved by maintaining the electrical performance, as demonstrated by the unharmed channel charge and mobility results.There are two key requirements for thermal management using heat spreading from the channel: first, a low thermal boundary resistance (TBR) between the hot spot in the channel and the heat spreader is required (in this study between GaN channel and diamond). Second, a low thermal resistance path to the heat-sink is crucial from the diamond layer which is directly proportional to diamond’s thermal conductivity (TC). In collaboration with Univ of Bristol, we have reported a TBR of ~3 m2K/GW, to date, known to be the lowest reported TBR for GaN HEMT technology. Diamond-GaN TBR depends strongly on the interface smoothness and the thickness of interfacial Si3N4 layer. A thinner Si3N4 resulted in lower TBR and allowed superior phonon coupling from the channel to the spreader. We have also measured a remarkably high TC for a 2 μm-thick diamond layer yielding over 650 W/m.K. The diamond grains are near isotropic in shape that allows excellent in-plane and cross-plane thermal conductivity. Achieving high TC within a thin film of diamond, grown heterogeneously, underscores the importance of our technique, since it reduces the residual stress when integrating with different materials that involves many thin layers like GaN/AlGaN HEMT epi-layers.β-Ga2O3 is an emerging ultra-wide bandgap material showing promises for both power and RF devices. However, the material’s low thermal conductivity poses to be a challenge for efficient power delivery (at any frequencies). PC diamond was successfully grown on (‾¯201)β-Ga2O3 using proper nucleation technique and thermal characterizations were conducted. A thermal conductivity (diamond + nucleation) and thermal boundary resistance at the diamond/β-Ga2O3 interface of 110 ± 33 W/mK and 30.2 ± 1.8 m2K/GW, respectively were measured.Our current results demonstrates a very promising roadmap for wide bandgap semiconductors via diamond integration.