Room Temperature Annealing Research Articles

Synthesis of porous SnO2@Fe2O3 core-shell triple-shelled boxes with selective and rapid response towards HCHO

Heterogenous SnO2@Fe2O3 core-shell triple-layer boxes (TBs) are successfully prepared through using a combination of room-temperature hydrolyzation and annealing treatment on SnO2 double-layer boxes (DBs). The crystallinity, morphology, and microstructure of as-prepared SnO2@Fe2O3 TBs are detailedly characterized. Compared with those of referenced pristine SnO2 or Fe2O3 nanostructures, the overall cubic configuration of heterogeneous SnO2@Fe2O3 with hollow interiors retains largely unaltered. Meanwhile, sensor based on SnO2@Fe2O3 samples synthesized with Fe2O3/SnO2 mole ratio of 1 exhibit superior response, excellent selectivity, shortened response-recovery time, and good long-time stability for formaldehyde (HCHO). It has the highest response (11.72) with the response/recovery time of 4 s/19 s to 50 ppm HCHO, respectively, and a low detection limit (1.07 to 200 ppb) for targeted HCHO under the optimal operating temperature (220 °C). The high absorption ability based on unique structural merits of hierarchically SnO2/Fe2O3 subunit-assembled porous multilayers and synergistic effect of SnO2/Fe2O3 heterojunction may contribute to their excellent HCHO sensing performance.

Divergent Polymer Superstructures from Protonated Poly(adenine) DNA and RNA.

Studies have shown that poly(adenine) DNA and RNA strands protonate at a low pH to form self-associating duplexes; however, the nanoscopic morphology of these structures is unclear. Here, we use Transition Electron Microscopy (TEM), Atomic Force Microscopy (AFM), dynamic light scattering (DLS), and fluorescence spectroscopy to show that both ribose identity (DNA or RNA) and assembly conditions (thermal or room-temperature annealing) dictate unique hierarchical structures for poly(adenine) sequences at a low pH. We show that while the thermodynamic product of protonating poly(adenine) DNA is a discrete dimer of two DNA strands, the kinetic product is a supramolecular polymer that branches and aggregates to form micron-diameter superstructures. In contrast, we find that protonated poly(A) RNA polymerizes into micrometer-length, twisted fibers under the same conditions. These divergent hierarchical morphologies highlight the amplification of subtle chemical differences between RNA and DNA into unique nanoscale behaviors. With the use of poly(adenine) strands spanning vaccine technologies, sensing, and dynamic biotechnology, understanding and controlling the underlying assembly pathways of these structures are critical to developing robust, programmable nanotechnologies.

Recovery at room temperature annealing on 4H–SiC SBDs by gamma irradiation

The impact of gamma irradiation and subsequent recovery at room temperature on the device performance of commercial 4H–SiC Schottky barrier diodes (SBDs) was investigated through the analysis of the electrical properties and the deep level transient spectroscopy (DLTS). The ideality factor (n) of the SBDs increased from 1.01 to 1.13 with an increasing irradiation dose, but recovered after 7 days of room temperature annealing. To determine Schottky barrier heights (ΦB), both current-voltage (I–V) and capacitance-voltage (C–V) measurements were performed. The results of the combined I–V and C–V analysis showed that a little variations in ΦB were consistent with the variations in irradiation dose, except for the ΦB calculated by C–V measurement at 30 kGy. Similarly, the ΦB recovered after 7 days at room temperature. DLTS analysis revealed the presence of Z1/Z2 traps in the samples after 7 days at room temperature annealing. These traps exhibited activation energies ranging from 0.46 eV to 0.55 eV. The trap concentration (NT) increased from 9.48 × 1012 cm−3 to 2.23 × 1013 cm−3 with the increasing irradiation dose. These findings indicate that gamma irradiation-induced point defects were the primary cause of the degradation of 4H–SiC SBDs.

Very long-time crystallization kinetics for ethylene-methacrylic acid ionomers neutralized with zinc, sodium, lithium and magnesium

Papers by our group [1] (Grady et al., 2013) and another group [2] (Paul et al. 2012) examined crystallization of random copolymers of ethylene and methacrylic acid after room temperature annealing. Similar conclusions were reached concerning the crystallization process; primary crystals were either unchanged or changed very little after annealing while secondary crystallization occurred over long time scales after annealing. The current work confirms these general conclusions for four different cations (Zn2+, Na+, Li+ and Mg2+), with the latter two not studied in either of the previous studies. Even after 6 years of annealing at room temperature, the crystallization rate is constant with logarithmic time, i.e. the material continues to crystallize. The acid copolymer does not crystallize with room temperature annealing, although secondary crystals of the acid copolymer thicken with annealing.

Enhancing SiGeSn nanocrystals SWIR photosensing by high passivation in nanocrystalline HfO2 matrix

SiGeSn nanocrystals (NCs) in oxides are of considerable interest for photo-effect applications due to the fine-tuning of the optical bandgap by quantum confinement in NCs. We present a detailed study regarding the silicon germanium tin (SiGeSn) NCs embedded in a nanocrystalline hafnium oxide (HfO2) matrix fabricated by using magnetron co-sputtering deposition at room temperature and rapid thermal annealing (RTA). The NCs were formed at temperatures in the range of 500–800 °C. RTA was performed to obtain SiGeSn NCs with surfaces passivated by the embedding HfO2 matrix. The formation of NCs and β-Sn segregation were discussed in relation to the deposition and processing conditions by employing HRTEM, XRD and Raman spectroscopy studies. The spectral photosensitivity exhibited up to 2000 nm in short-wavelength infrared (SWIR) depending on the Sn composition was obtained. Comparing to similar results on GeSn NCs in SiO2 matrix, the addition of Si offers a better thermal stability of SiGeSn NCs, while the use of HfO2 matrix results in better passivation of NCs increasing the SWIR photosensitivity at room temperature. These results suggest that SiGeSn NCs embedded in an HfO2 matrix are a promising material for SWIR optoelectronic devices.

Degradation of electrical performance and radiation damage mechanism of cascode GaN HEMT with 80 MeV proton

In this paper, proton irradiations on Cascode GaN HEMT power device with an energy of 80 MeV and fluences of 2 × 1011 p/cm2 and 6 × 1011 p/cm2 have been carried out, where the threshold voltages drifted negatively by 20.55% and 28.17%, respectively. After two months of room temperature annealing, the threshold voltages recovered 0.22 V and 0.27 V, respectively. The ionizing deposition energy (IEL) was simulated by using Monte Carlo software and TCAD, it the results showed that the value of IEL in Si MOSFET is 5 ∼ 6 orders higher than that in GaN HEMT, while the value of the non-ionizing energy loss (NIEL) is one order higher than that in GaN HEMT. It means that the proton irradiation on the Cascode depleted GaN HEMT is more prone to produce displacement damage. As a large number of electrons and holes pairs were existed on the incident path of Si MOSFET under the proton irradiation, the produced electron will be captured by the gate oxide traps at the SiO2/Si interface, and the holes be captured by the defects generated in displacement damage, resulting in the accumulation of oxide trapped charges. Then, the electrical performance of Si MOSFET degrades seriously, thereby affecting the performance of the entire device. The studies will be helpful for the radiation hardening of Cascode GaN HEMT.

Structure of monolayer iron nitride islands on Cu(001) revisited

We revisited the structure of monolayer iron nitride islands grown on Cu(001) using the well-established procedure, i.e. by bombarding the substrate with low-energy N+ ions, depositing Fe at room temperature and annealing in ultra-high vacuum (UHV). The geometric parameters of the obtained iron nitride were matching those of the “Fe2N” phase described in the literature and constituting the middle-plane-cut of the γ′-Fe4N unit cell. However, the atomic structure was found to exhibit an out-of-plane corrugation not reported by other authors so far. Moreover, the islands had an Fe1.3N stoichiometry and were characterized by a much higher work function value than the one predicted theoretically for the Fe2N phase. Based on these findings, we propose a new structural model for monolayer iron nitride on Cu(001), in which an additional N atom resides on top of every second Fe atom in each atomic row of the Fe2N. We also show that the Fe1.33N islands may be reduced to species with Fe2N stoichiometry through the exposure to O2 at room temperature and subsequent annealing in UHV. Thus, direct formation of the Fe2N phase under specific experimental conditions, as indicated by other authors, may be also possible.

High-quality VO2 films synthesized on polymer substrates using room-temperature pulsed laser deposition and annealing

With the growing trend towards portable and adaptable devices in various fields, the demand for flexible electronics and coatings utilizing phase transition materials like VO2 as a functional layer is rising. However, depositing high-quality crystalline VO2 films directly onto polymer substrates remains challenging due to the thermosensitivity of such materials being barely compatible with usual VO2 deposition methods. In this study, we present a simple method for directly growing VO2 on Kapton substrates. VOx films were first deposited onto the Kapton substrate at room temperature using pulsed laser deposition and subsequently annealed in an oxygen atmosphere at 390 °C. The electrical and optical properties of the VO2/Kapton samples with different film thicknesses were investigated. The 200 nm-thick vanadium dioxide films exhibit the best resistivity contrast with 3.1 orders of magnitude (OOM), while the 50 nm-thick films show the best transmittance change of 54 % at 2500 nm. The switching performances are comparable or even superior to those achieved previously using more complicated synthesis processes such as film transfer, introduction of buffer layers, and ink injection. Additionally, by coupling W elemental doping and thin film strain, we successfully tuned the VO2 transition temperature to room temperature with a dopant concentration of only 1.1 at.% while maintaining a high electrical contrast (2 OOM). The impressive electrical and optical transition performance of the VO2/Kapton samples, combined with their tunable transition temperature, makes them promising candidates for flexible electronic devices and thermochromic smart coatings.

Study on annealing effect of bipolar transistors at different temperatures after total dose irradiation

The article investigates the annealing process of bipolar transistors after total dose irradiation, using the GLPNP transistor as the research object. After total dose irradiation, room temperature and high temperature annealing tests were carried out. Gummel curve, GS curve and SS curve of bipolar transistor are obtained by I/V scanning, gate scanning and sub-threshold scanning. The evolution behavior of radiation-induced oxide trap charges and interface state damage defects during annealing of bipolar transistors at different temperatures was quantitatively analyzed by different microscopic defect characterization methods. Generally speaking, this study is of great significance to better understand the recovery mechanism of electrical properties of bipolar transistors during annealing after total dose irradiation, and can provide reference for the design, application and radiation-hard of transistors.

Measurements of radiation effects in an antifuse FPGA

This paper presents the irradiation and the measurement analysis for a commercial antifuse Field Programmable Gate Array (FPGA) from Microsemi’s Axcelerator family, part number AX250. Following proton and X-ray beam irradiation, at very high dose rate above 1krad/s, the total ionizing dose (TID) first effects were visible around 260 krad (SiO 2), and this threshold value increases at lower radiation dose rates. We expect for most space and accelerator applications that this value will be at least several Mrads, or even that the FPGA might never reach this threshold. At very high radiation dose rates, TID-induced leakage currents were observed in the device. FPGA data were recorded continuously for more than 100 h after each irradiation with a fully operating FPGA. Quantitatively, the room-temperature annealing of the radiation-induced defects leads to a fast decrease of the device leakage current by a factor of 7 in the first 100 h after irradiation. The last measurements done after three months place the currents to within 30% to 70 % relative to the before-irradiation values in case of two tested FPGA. Several firmware configurations were used to test different logic resources and to measure single event upsets (SEUs). An upper limit of SEU logic cross-section was found to be (2.56 ± 0.51) ⋅ 10−13 cm 2/FPGA for dose rates around 1krad/s. SEU cross-section values for RAM blocks have on average a value of (3.72 ± 0.8) ⋅ 10−14 cm 2/bit. The complete list of results is given and the effects are extrapolated to a high-energy physics experiment environment — LHCb RICH at CERN.

Reduced He ion irradiation damage in ZrC-based high-entropy ceramics

Excellent irradiation resistance is the basic property of nuclear materials to keep nuclear safety. The high-entropy design has great potential to improve the irradiation resistance of the nuclear materials, which has been proven in alloys. However, whether or not high entropy can also improve the irradiation resistance of ceramics, especially the mechanism therein still needs to be uncovered. In this work, the irradiation and helium (He) behaviors of zirconium carbide (ZrC)-based high-entropy ceramics (HECs), i.e., (Zr_0.2Ti_0.2Nb_0.2Ta_0.2W_0.2)C, were investigated and compared with those of ZrC under 540 keV He ion irradiation with a dose of 1×10¹⁷ cm⁻² at room temperature and subsequent annealing. Both ZrC and (Zr_0.2Ti_0.2Nb_0.2Ta_0.2W_0.2)C maintain lattice integrity after irradiation, while the irradiation-induced lattice expansion is smaller in (Zr_0.2Ti_0.2Nb_0.2Ta_0.2W_0.2)C (0.78%) with highly thermodynamic stability than that in ZrC (0.91%). After annealing at 800 ℃, ZrC exhibits the residual 0.20% lattice expansion, while (Zr_0.2Ti_0.2Nb_0.2Ta_0.2W_0.2)C shows only 0.10%. Full recovery of the lattice parameter (<i>a</i>) is achieved for both ceramics after annealing at 1500 ℃. In addition, the high entropy in the meantime brings about the favorable structural evolution phenomena including smaller He bubbles that are evenly distributed without abnormal coarsening or aggregation, segregation, and shorter and sparser dislocation. The excellent irradiation resistance is related to the high-entropy-induced phase stability, sluggish diffusion of defects, and stress dispersion along with the production of vacancies by valence compensation. The present study indicates a high potential of high-entropy carbides in irradiation resistance applications.

Synergic Combination of Strength and Ductility through Both Grain Refinement and Precipitation in Al0.3CoCrNi Medium‐Entropy Alloy

To improve the tensile properties of Al0.3CoCrNi (at%), herein, medium‐entropy alloys at room temperature, high‐pressure torsion (HPT), and appropriate annealing are presented. Severe deformation due to HPT causes fine grains and evenly distributed B2 and σ precipitates with a nanometer scale through an annealing procedure. A synergic combination of yield strength over 1.0 GPa and uniform elongation over 25% is obtained due to the simultaneous utilization of both grain refinement and precipitation strengthening.

Effect of simultaneous electrical and mechanical stressing on porosity of Ti3C2T x MXene films

MXenes are atomically layered carbides and nitrides of transition metals that have potential for micro-devices applications in energy storage, conversion, and transport. This emerging family of materials is typically studied as nanosheets or ultra-thin films, for which the internal defects are mostly nanoscale flake-flake interface separation type. However, micro-devices applications would require thicker films, which exhibit very high density of microscale pores. Electrical conductivity of thicker MXenes is significantly lower than nanosheets, and the physics of defect size and density control are also different and less understood. Current art is to perform high temperature annealing to improve the electrical conductivity, which can structurally alter or degrade MXene. The key contribution of this study is a room-temperature annealing process that exploits the synergy between electrical pulses and compressive mechanical loading. Experimental results indicate over a 90% increase in electrical conductivity, which reflects a decrease in void size and density. In the absence of compressive loading, the same process resulted in a conductivity increase of approximately 75%. Analytical spectroscopy and microscopy indicated that the proposed multi-stimuli process kept the MXene composition intact while significantly decreasing the void size and density.

The effect of in situ irradiation on the superconducting performance of REBa2Cu3O7−δ-coated conductors

Commercial fusion power plants will require strong magnetic fields that can only be achieved using state-of-the-art high-temperature superconductors in the form of REBa2Cu3O7−δ-coated conductors. In operation in a fusion machine, the magnet windings will be exposed to fast neutrons that are known to adversely affect the superconducting properties of REBa2Cu3O7−δ compounds. However, very little is known about how these materials will perform when they are irradiated at cryogenic temperatures. Here, we use a bespoke in situ test rig to show that helium ion irradiation produces a similar degradation in properties regardless of temperature, but room-temperature annealing leads to substantial recovery in the properties of cold-irradiated samples. We also report the first attempt at measuring the superconducting properties while the ion beam is incident on the sample, showing that the current that the superconductor can sustain is reduced by a factor of three when the beam is on.Impact statementREBa2Cu3O7−δ high-temperature superconductors are an enabling technology for plasma confinement magnets in compact commercial fusion power plants, owing to their ability to carry very high current densities when processed as quasi-single crystals in the form of coated conductors. In service in a fusion device, the magnet windings will be exposed to a flux of fast neutrons that will induce structural damage that will adversely affect the superconducting performance, but very little data are currently available on the effect of irradiation at the cryogenic temperatures relevant for superconducting magnets. Moreover, even room-temperature annealing substantially affects superconducting properties after irradiation, so to obtain key technical data for fusion magnet designers, it is important to measure these properties in situ, under irradiation. This work shows that for the first time, it is important to consider how energetic particles directly influence superconductivity during irradiation because we observe a reduction in zero-resistance current by a factor of as much as three when an ion beam is incident on the sample. Although neutrons will not interact with the material in the same way as charged ions, primary knock-on ions from neutron damage are expected to have a similar effect to the He+ ions used in our study.Graphical abstract

Radiation damage effects of protons and X-rays on silicon photomultipliers

Silicon photomultipliers (SiPMs) are highly-sensitive photodetectors emerging as the technology of choice for many applications. In high-energy physics experiments and as the detectors for space instruments they are often exposed to a large amount of irradiation. In recent years, there has been an increasing interest in assessing the performance deterioration of such detectors after ionizing and non-ionizing radiation, such as protons, neutrons and X or gamma rays. It is interesting to compare the radiation damage effects on several types of SiPMs, to assess the main deterioration mechanisms on SiPM performances. In this work we report on the irradiation by protons and X-rays of several types of small-area ( ∼ 1 mm 2 ) SiPMs, produced in FBK with different technologies. We show and compare the most interesting results of the online measurements, taken just after each irradiation step, for both irradiations. We performed and monitored the current variation during a room temperature annealing. Finally we characterized all the main functional performance of the irradiation SiPMs, highlighting the most interesting variations.

A superior strength-ductility synergy of Al0.1CrFeCoNi high-entropy alloy with fully recrystallized ultrafine grains and annealing twins

• Giant strengthening in Al 0.1 CrFeCoNi by cold rolling and short-time annealing. • Al 0.1 CrFeCoNi possesses yield strength of 885 MPa and uniform elongation of 23.4%. • Ultrafine-grained structure and multiple deformation twins lead to high strength. Grain refinement usually makes the materials stronger, while ductility has a dramatic loss. Here, a superior tensile strength–ductility synergy in a fully recrystallized ultrafine-grained (UFG) Al 0.1 CrFeCoNi with abundant annealing twins was achieved by cold rolling at room temperature and short-time annealing. The microstructure characterization using electron backscattered scattering diffraction demonstrates that abundant geometrically necessary dislocations (GNDs) gather around the grain boundaries and twin boundaries after tensile deformation. Although coarse-grained (CG) samples undergo a larger plastic deformation than UFG samples, the GND density decreases with grain size ranging from UFG to CG. Transmission electron microscopy results reveal that the annealing twin boundary, which effectively hinders the dislocation slip and stores dislocation in grain interior, and the activation of multiple deformation twins are responsible for the superior strength–ductility synergy and work hardening ability. In addition, the yield strength of fully recrystallized Al 0.1 CrFeCoNi follows a Hall–Petch relationship ( σ y = 24 + 676 d –1/2 ), where d takes into account both grain boundaries and annealing twin boundaries. The strengthening effects of grain boundaries and annealing twin boundaries were also evaluated separately.

Helium and strontium co-implantation into SiC at room temperature and isochronal annealing: Structural evolution of SiC and migration behaviour of strontium

Understanding the structural evolution of SiC implanted with fission product surrogates in the presence of helium (He) is of importance for its application in both fission and fusion rectors. In this study, polycrystalline SiC wafers were sequentially co-implanted with 360 keV Sr and 21.5 keV He ions to a fluence of 2 × 1016 cm-2 and 1 × 1017 cm-2 at room temperature, respectively. The samples were then isochronally annealed in temperatures ranging from 1000 to 1300 °C for 5 h. Transmission electron microscopy (TEM) showed the formation of He-nanobubbles corresponding to helium's projected range. While scanning electron microscopy (SEM) revealed the formation of cornflower-like structures on the surface of the Sr + He–SiC samples after annealing. These were confirmed to be holes by atomic force microscopy (AFM), as a result of exfoliation and pressurized out-diffusion of helium gas from the samples. The Sr + He–SiC samples were completely amorphized characterized by the formation of the homonuclear bonds in Raman spectroscopy. The recovery process after annealing in the Sr + He–SiC samples resulted in the formation of graphite due to antisite defects driven by the growth of holes above the threshold chemical disorder. Time-of-flight heavy ions elastic recoil detection analysis (Tof-ERDA) showed that almost all helium out-diffused after annealing at 1000 °C and Sr atoms trapped in He cavities.

Radiation Damage and Recovery Mechanisms in Scintillating Fibers

Optical scintillating bers lose their transparencies when exposed to radiation. Nearly all studies of radiation damage to optical bers so far only characterize this darkening with a single period of irradiation. Following the irradiation, bers undergo room temperature annealing, and regain some of their transparencies. We tested the irradiation-recovery characteristics of scintillating fibers in four consecutive cycles. In addition, three optical scintillating bers were irradiated at 22 Gy per minute for over 15 hours, and their transmittance were measured each minute by pulsing a light source through the bers. Here, we report on the in-situ characterization of the transmittance vs radiation exposure, allowing future applications to better predict the lifetime of the scintillating bers.

Room temperature annealing of SnS2 films with electron impulse force

Tin disulfide (SnS2) is a layered metal dichalcogenide material with wide bandgap favoring electronics, sensors, photovoltaics, and water splitting applications. Atomic layer deposition can precisely control film thickness over large area, which is important for device applications. The as-deposited SnS2 shows poor crystallinity, which is difficult to anneal with high temperature because of de-sulfurization. We demonstrate room temperature annealing by exploiting electron impulse force. High current density pulses were applied with very low duty cycle to suppress heat accumulation, while the momentum of the electron pulses interacted with the defects and grain boundaries. For seven-layer thick tin di-sulfide specimens, resistivity was decreased by ten times at ambient temperature. Enhancement of crystallinity was analyzed with Raman spectroscopy and transmission electron microscopy followed by geometric phase analysis. The demonstrated technique can impact applications where post-synthesis annealing requires high temperature and special environment.

(Invited) Micromechanical Aspects of GaN Hemt Performance and Reliability

Performance and reliability of microelectronic devices are governed by the mechanical strain. Typically, strain engineering implies uniformly distributed strain. However, we offer a different perspective by hypothesizing that very small but localized strain (or stress) may have significant impact on the overall behavior of AlGaN/GaN high electron mobility transistors (HEMTs). Micro to nanoscale confined mechanical stress fields may develop unavoidably and are ignored because their spatial average is insignificant. We exploit high resolution techniques such as transmission electron microscopy (TEM) and micro-Raman spectroscopy to spatially resolve the stress field in GaN HEMTs to demonstrate the stress localization and then radiation effects.To study stress localization effects on the global electrical characteristics, we introduced a highly localized strain relief by milling a 20×30 μm2 micro trench about 70 μm deep on the backside of an 800×840 μm2 size HEMT die. The resulting local relaxation of in-plane residual strain was mapped using micro-Raman technique. Our results show that a decrease of only 0.02% strain can decrease the overall output saturation current up to ~20 %. The drop of output current is attributed to reduced two-dimensional electron gas (2DEG) sheet carrier density and electron mobility due to the strain relief in the device layers. However, the mechanistic process of strain relief also causes defect generation at the interfaces, which increases leakage current. Our technique for localized strain re-distribution could be an effective tool to surrogate the influence of inherent localized strain build-up across the channel of electronic devices.To study radiation effects, we exposed the HEMTs to gamma rays (up to 10 megaRads dose at 180 kiloRads per hour). We report the thermal and mechanical responses in terms of the changes in lattice strain and temperature, which were simultaneously characterized by changes in phonon frequency of E2 (high) and A1 (LO) from on- state and unpowered/pinched off reference states. Lower doses of radiation improved the electrical properties, however degradation initiated at about 1 megaRads. We observed about 16% decrease in saturation current and 6% decrease in transconductance at the highest dose. However, leakage current increase by 3 orders of magnitude was the most notable radiation effect. We observed temperature increase by 40% and mechanical stress increase by a factor of three at dose of 10 megaRads compared to the pristine devices. Spatial mapping of mechanical stress along the channel identifies the gate region as mechanically affected area, whereas the thermal degradation was mostly uniform. Transmission electron microscopy showed contrast changes reflecting high vacancy concentration in the gate region. These findings suggest that localized stress (mechanical hotspots) may increases vulnerability to radiation damage by accommodating higher concentration of defects that promote leakage current.Finally, we present experimental results on a novel concept of electron wind force driven room temperature annealing of GaN and SiC devices. This technique was applied on Gamma irradiated HEMT and SiC diodes. We demonstrate full recovery of the HEMTs irradiated to 10 mega-Rads gamma radiation. About 200% performance improvement was recorded for the SiC diodes. Our hypothesis is that mechanical stress waves are instrumental in eliminating interfacial defects.