Inversion Regime Research Articles

Mechanical properties of (Ni, Fe)Cr2O4 polycrystal spinels studied by molecular dynamics simulations.

The elastic moduli and mechanical properties at the onset of crack in nanocrystalline and nanoporous (Ni, Fe)Cr2O4 compounds with a spinel structure are investigated by molecular dynamics simulations. The polycrystalline structures generated contain nanograins from 2.5 to 30nm in diameter. These structures are representative of the internal corrosion layer in nickel-based alloys. These simulations enabled us to establish the evolution of elastic moduli as a function of the composition, porosity, and grain size of the polycrystals. From this evolution, the initial database for the elastic properties of corrosion layers based on von Bertalanffy growth functions was determined. The onset of crack in polycrystals is also investigated via uniaxial tensile and shear deformation. Under shear deformation, flow stress as a function of grain size follows normal and inverse Hall-Petch regimes. The regime change occurs for grain sizes around 10nm. For grain sizes under this threshold, shear banding involving collective translation and rotation of nanograins dominates the plastic deformation. For grain sizes greater than 10nm, phase transition inside grains from a spinel to a post-spinel-like structure is observed as well. In that case, phase transition dominates the plastic deformation. Under uniaxial tensile deformation, intergranular decohesion occurs. The general law as a function of grain size for toughness, which is the material's capacity to absorb elastic and plastic energy prior to failure, is also established.

Fluid flow in the Katanga Supergroup: From Lufilian brittle tectonic stages to the post-Lufilian period (Democratic Republic of Congo)

The metasedimentary rock succession of the Neoproterozoic-Cambrian Katanga Supergroup in the Central Africa Copperbelt shows evidence of several complex tectonic events. The deformation of this supergroup started from the tectonic inversion at about 570 Ma and lasted up to today, but reached paroxysm at ∼550 Ma. This long period was characterized by folding and faulting throughout multiple compressive and extensional events, which controlled the regional fluid flow on the one hand, and played an important role during formation of the stratiform to stratabound Cu-Co (Ni, U) deposits and the polymetallic Cu-Zn-Pb (Ag, Ge, Mo, Cd) vein type deposits on the other hand. Based on the structural analysis and paleostress reconstruction, coupled with fluid inclusion characterization from mineralized structures in rocks from the Nguba, Kundelungu and Biano Groups, this study demonstrates that the composition of hydrothermal fluids changed during brittle tectonic deformation during the Lufilian orogeny and subsequent uplift and post-Lufilian faulting.During early brittle tectonic deformation along strike slip faults with sinistral and dextral movement related to a NE-SW transpression, the Cu-mineralizing fluid was hypersaline (27.9–31.1 eq. wt% NaCl) with moderate temperatures (Th = 128–216 °C). The subsequent Cu or Cu (Zn, Pb) mineralization formed within an E-W extensional stress regime, related to the late Lufilian orogenic collapse. The fluid inclusions present in the gangue minerals associated with this latter mineralization show a large range in Th (50–264 °C) and salinity (26.7–36.0 eq. wt% NaCl). The decrease in temperature is interpreted to be due to migration of the fluids at shallower depth in the subsurface after uplift and erosion of the orogen. The increased salinity of the fluid is related to the dissolution of evaporites, mainly NaCl. A second H2O-NaCl-CaCl2 fluid with a homogenization temperature below 55 °C has also been found associated with this brittle stage and mineralization phase, but only in rocks belonging to the Kundelungu Group. A third mineralization phase, also characterized by Cu or Cu (Zn, Pb), formed during the post-Lufilian period within a NW-SE transpressional inversion regime. The fluid inclusion in the gangue minerals of this mineralization phase have a smaller range in homogenization temperature (Th = 37–172 °C) and the largest range in salinity (0.71–30 eq. wt% NaCl), compared to the earlier fluid inclusions generations. This large range in salinity may be explained by the mixing of a high salinity fluid, already present during the earlier tectonic stages in the sedimentary basin, with meteoric water. During the more recent rift-related extension, a fluid with again a large and higher range in homogenization temperatures (Th = 47–257 °C) and with a typical low salinity (<10 eq. wt% NaCl) has been recognized in minerals filling NNE-SSW to NE-SW oriented faults and fractures. The upward migration of a relatively low-salinity fluid from deeper parts in the subsurface explains the variation in the temperatures observed with this tectonic event.

High-power hollow-core fiber gas laser at 3.1 µm with a linear-cavity structure.

Mid-infrared hollow-core fiber (HCF) gas lasers based on a population inversion regime of gas molecules have made advanced development in recent years, but mostly with single-pass cavity-free structures. Here, we demonstrated a 3.1 µm high-power acetylene-filled HCF continuous wave (CW) laser and a self-Q-switched pulse laser with a linear-cavity structure. This configuration not only facilitates the transformation of amplified spontaneous emission into the laser output but also enhances the coherence of the light source and imparts distinct cavity mode characteristics. Harnessing a homemade high-power 1535 nm single-frequency fiber laser that served as the pump source, a CW laser output of 8.23 W at 3.1 µm was achieved, which is over three orders of magnitude higher than those in reported works so far. The corresponding slope efficiency of 31.8% and beam quality of Mx 2 = 1.18 and My 2 = 1.15 were characterized. When the gas pressure was up to 50 mbar, the laser generated a 3.1 µm self-Q-switched pulse with an output power of 1.98 W as well as a pulse width of 45 ns under the repetition rate of 4.59 MHz. To the best of our knowledge, this is the first time that an HCF gas laser achieves a self-Q-switched pulse. Future studies will aim to further optimize the experimental setup, potentially enabling the direct generation of picosecond pulses in the mid-infrared wavelength band.

Effect of dynamic strain ageing on flow stress and critical strain for jerky flow in Al-Mg alloys

A comprehensive approach addressing the flow behavior and the critical strain for the initiation of serrations in Al-Mg alloys is developed in the present work. The basic premise of the approach is that the solute atmosphere influences the friction as well as the strain hardening component of the flow stress. The friction effect of the solute cloud is modeled by considering the interplay between the characteristic solute migration time and the dislocation waiting time according to the cross-core diffusion mechanism. The impact on strain hardening is modeled by considering the apparent strengthening of the forest dislocations because of formation of solute aggregates near the vicinity of dislocation junctions. The apparent forest strengthening effect scales as the square root of the ratio of solute concentration in vicinity of the dislocation junctions and the bulk solute concentration. The modified constitutive model is validated against experimental flow curves obtained for strain rates varying over several orders of magnitude. It was observed that the modified constitutive model outperforms the standard constitutive model (considers only the friction effect of solute atmosphere) in predicting the flow curves in the dynamic strain aging domain. Furthermore, the modified constitutive model also accurately predicts the critical strain for the initiation of the jerky flow in both the normal and inverse regimes of the critical strain versus strain rate curve. Additional validation of the modified constitutive model is provided by dislocation character and density measurements via X-ray diffractograms, dislocation structure investigation via transmission electron microscopy along with fracture surface analysis.

Magneto-induced topological phase transition in inverted InAs/GaSb bilayers

We report a magneto-induced topological phase transition in inverted InAs/GaSb bilayers from a quantum spin Hall insulator to a normal insulator. We utilize a dual-gated Corbino device in which the degree of band inversion, or equivalently the electron and hole densities, can be continuously tuned. We observe a topological phase transition around the magnetic field where a band crossing occurs, accompanied by a bulk-gap closure characterized by a bulk conductance peak (BCP). In another set of experiments, we study the transition under a tilted magnetic field (tilt angle ). We observe the characteristic magnetoconductance around BCP as a function of , which dramatically depends on the density of the bilayers. In a relatively deep inversion (hence a higher density) regime, where the electron-hole hybridization dominates the excitonic interaction, the BCP grows with . On the contrary, in a shallowly inverted (a lower density) regime, where the excitonic interaction dominates the hybridization, the BCP is suppressed indicating a smooth crossover without a gap closure. This suggests the existence of a low-density, correlated insulator with spontaneous symmetry breaking near the critical point. Our highly controllable electron-hole system offers an ideal platform to study interacting topological states as proposed by recent theories. Published by the American Physical Society 2024

Analysis on the capacitance-voltage characteristics of metal-insulator-semiconductor capacitors based on thermally evaporated WOx on n- and p- type crystalline silicon

Tungsten oxide (WOx) thin films were deposited on n- and p-type crystalline silicon (c-Si) wafers by thermal evaporation technique at room temperature. The electrical characterization of Ag/WOx/n-Si and Ag/WOx/p-Si metal–insulator-semiconductor (MIS) capacitors were examined by the capacitance- and conductance-voltage measurements as a function of applied frequency in the 10 kHz 10 MHz range. The admittance properties of both MIS devices have been evaluated by analyzing the interfacial nature and bulk c-Si in accumulation, depletion, and inversion regimes. The capacitance responses of interface traps, bulk c-Si, depletion, and shallow states at the WOx/c-Si interface indicated the appearance of the capacitance peaks in depletion and inversion regimes for Ag/WOx/n-Si and Ag/WOx/p-Si devices. From C-V characterization, various parameters such as the depletion layer width, depletion capacitance, flat-band voltage, total charge density, and net ionized state density were calculated as a function of applied frequency. For Ag/WOx/n-Si device, the total charge density and barrier height values of 7.642 × 10−9 C and 1.119 eV at 1 MHz, respectively, were obtained. The same parameters were calculated to be 5.887 × 10−8 C and 1.107 eV for Ag/WOx/p-Si. The results demonstrated that interfacial nature of WOx film significantly governs the electronic characteristics of the c-Si based MIS devices.

Numerical Validation of the Inverse Cascade of Surface Gravity Wave Action.

We report numerical simulations of surface gravity waves forced at small scale and the subsequent inverse cascade of wave action. We combine the spectral approach to simulating weakly nonlinear waves with the capabilities of modern graphics processing units to reach unprecedented scale separation between the forcing and domain scales. The resulting broad inertial range allows for an unambiguous confirmation of the theoretical prediction for the spectrum in the inverse cascade regime, both in terms of spectral index and dependence of the spectral level on the action flux.

Thermal stability of electrodeposited nanostructured high-entropy alloys

Over the past decade, the study of nanostructured high-entropy alloys (HEAs) has attracted great attention due to their high strength (grain boundary hardening) and improved thermal stability over conventional nanostructured metals and alloys. However, a lingering issue yet to be resolved by these studies is that of commercial viability; the synthesis processes used to date are costly, not easily scalable, and energy intensive. This work examines the thermal stability and mechanical properties of electrodeposited nanostructured HEAs, towards establishing a cost-effective and versatile synthesis route to commercialize this underutilized material class. Nanocrystalline, amorphous, and nanoglass alloys of NiFeCoW, NiFeCoMo, and NiFeCoMoW were systematically characterized to assess the stability of their structure and mechanical properties, compared against conventional nanocrystalline materials and HEA counterparts. The structural stability of these electrodeposited HEAs was shown to improve with increasing number of elements, from a peak temperature for grain growth of ∼270 °C in pure nanocrystalline Ni, to ∼500 °C in electrodeposited HEAs, corresponding to a near doubling of the activation energy for grain growth from 1.3 eV (Ni) to a maximum of 3.1 eV (NiFeCoW). This improved stability was matched with a 60 % increase in hardness after annealing to the point of nanograin nucleation (∼500 °C), to a maximum hardness of ∼8.4 GPa. Such hardening trends followed an extrinsic inverse-to-regular Hall-Petch relationship, where the inverse regime was largely dominated by grain boundary relaxation and nanoglass structural breakdown. With these results, we have established electrodeposition as a promising candidate route for fabricating nanostructured HEAs for applications at elevated temperatures.

A matching-based machine learning approach to estimating optimal dynamic treatment regimes with time-to-event outcomes.

Observational data (e.g. electronic health records) has become increasingly important in evidence-based research on dynamic treatment regimes, which tailor treatments over time to patients based on their characteristics and evolving clinical history. It is of great interest for clinicians and statisticians to identify an optimal dynamic treatment regime that can produce the best expected clinical outcome for each individual and thus maximize the treatment benefit over the population. Observational data impose various challenges for using statistical tools to estimate optimal dynamic treatment regimes. Notably, the task becomes more sophisticated when the clinical outcome of primary interest is time-to-event. Here, we propose a matching-based machine learning method to identify the optimal dynamic treatment regime with time-to-event outcomes subject to right-censoring using electronic health record data. In contrast to the established inverse probability weighting-based dynamic treatment regime methods, our proposed approach provides better protection against model misspecification and extreme weights in the context of treatment sequences, effectively addressing a prevalent challenge in the longitudinal analysis of electronic health record data. In simulations, the proposed method demonstrates robust performance across a range of scenarios. In addition, we illustrate the method with an application to estimate optimal dynamic treatment regimes for patients with advanced non-small cell lung cancer using a real-world, nationwide electronic health record database from Flatiron Health.

Collective coherent emission of electrons in strong laser fields and perspective for hard x-ray lasers

Coherent motion of particles in a plasma can imprint itself on radiation. The recent advent of high-power lasers—allowing the nonlinear inverse Compton-scattering regime to be reached—has opened the possibility of looking at collective effects in laser–plasma interactions. Under certain conditions, the collective interaction of many electrons with a laser pulse can generate coherent radiation in the hard x-ray regime. This perspective paper explains the limitations under which such a regime might be attained.

Voltage and frequency reliant interface traps and their lifetimes of the MPS structures interlayered with CdTe:PVA via the admittance method

In this work, to gain detailed information about the electrical characteristics, interface traps (Dit), and their lifetimes (τ) of the metal-polymer-semiconductor (MPS) type structures, admittance measurements performed in wide frequency and voltage ranges have been utilized. At the outset, the intercept, and slope of the 1/C2 vs V curve were used to unveil the density of acceptor-atoms (NA), depletion-layer width (WD), and barrier-height (ΦB). All these parameters show strong frequency dependence with the effect of the Dit, interlayer, interface, and dipole polarization, especially at low and moderate frequencies. Therefore, Dit and τ were determined from the admittance method. The measured C -G/ω vs V curves were adjusted for higher frequencies taking into account the series-resistance effect. Experimental results indicate the strong effect of the Rs value on the capacitance and conductance values only at the accumulation-regime for higher-frequencies whereas the Dit effect in both inversion and depletion regimes for lower-frequencies.

A Surface Potential Model for Metal-Oxide-Semiconductor Transistors Operating near the Threshold Voltage

Device physics and accurate transistor modeling are necessary to reduce the operating voltage near the threshold for power-constrained circuits. Conventional device modeling for metal-oxide-semiconductor (MOS) transistors focuses on operations in either strong or weak inversion regimes, and the electrostatics at gate biases near the threshold voltage is rarely studied. This research proposed an analytical model to describe the distribution of the surface potential along the channel for near-threshold operation. Numerical device simulations were also performed to investigate the electrostatics near the threshold voltage. The numerical simulation with constant carrier mobility showed an overshoot in the transconductance due to decay of the lateral electric field with gate bias. The decay of the lateral electric field was predicted by the proposed analytical surface potential model which considered widening the channel length with flooding of the inversion carriers in the channel and gate overlap regions. The channel length widening effect saturated as the gate bias further increased. Therefore, evident transconductance overshoot was observed near the threshold voltage in short-channel devices.

A Physical Model for the Observed Inverse Energy Cascade in Typhoon Boundary Layers

AbstractThe knowledge of the observed inverse energy cascade in typhoon boundary layers holds significant implications for understanding the formation, enhancement, and deformation of typhoons. This study reveals that the observed inverse energy cascade originates from the rapid rotation of typhoons. The transition from the direct energy cascade regime to the inverse energy cascade regime can be characterized by the Zeman length scale. The turbulence structures behave as two dimensional above the Zeman length scale. Through symmetry analysis, it is discovered that the ratio of the inverse energy cascade flux to the direct energy cascade flux is proportional to the turbulence Rossby number with a power of −2. These findings offer a framework for incorporating the inverse energy cascade into the turbulence parameterizations and improving typhoon modeling.

Quantum transport and shot noise in two-dimensional semi-Dirac system

Two-dimensional (2D) semi-Dirac systems, such as 2D black phosphorus and arsenene, can exhibit a rich topological phase transition between insulating, semi-Dirac, and band inversion phases when subjected to an external modulation. How these phase transitions manifest within the quantum transport and shot noise signatures remains an open question thus far. Here, we show that the Fano factor converges to the universal F ≈ 0.179 at the semi-Dirac phase and transits between the sub-Poissonian ( F ≈ 1 / 3) and the Poissonian shot noise ( F ≈ 1) limit at the band inversion and the insulating phase, respectively. Furthermore, the conductance of a 2D semi-Dirac system converges to the contrasting limit of G / G 0 → 1 / d and G / G 0 → 0 at the band inversion and the insulating phases, respectively. The quantum tunneling spectra exhibits a peculiar coexistence of massless and massive Dirac quasiparticles in the band inversion regime, thus providing a versatile sandbox to study the tunneling behavior of various Dirac quasiparticles. These findings reveal the rich interplay between band topology and quantum transport signatures, which may serve as smoking gun signatures for the experimental studies of semi-Dirac systems near the topological phase transition.

Laminar separation bubble on a rotating cylinder in uniform flow

We study the effect of spin ( 0 ≤ α ≤ 2) of a cylinder, placed in uniform flow, on the transition of the boundary layer. Large Eddy Simulation, with the Sigma turbulence model to account for the sub-grid scales, is carried out using a stabilized finite element formulation. The Reynolds numbers ( R e = 0.6 × 10 5 and 1.0 × 10 5) lie in the high-subcritical regime for a non-rotating cylinder where the boundary layer separates in a laminar state and does not reattach. Magnus effect is observed at low α wherein separation is delayed on the retreating side and preponed on the advancing side, resulting in a lift force that increases with increase in α. At a certain critical α, the boundary layer on the advancing side transitions to a turbulent state, causing it to reattach. A laminar separation bubble (LSB) forms, significantly delaying the final separation and increasing suction. At R e = 1.0 × 10 5, this suction overcomes that on the retreating side, leading to a reversal in the direction of lift force, referred to as the inverse Magnus effect. The LSB is accompanied by weakened vortex shedding at increased frequency. The spatial extent of the LSB and the magnitude of reverse lift, at a given Re, decreases with increase in α. The lift force changes direction yet again at a certain α marking the end of the inverse Magnus effect regime and beginning of the second Magnus effect regime. The LSB vanishes beyond a certain spin rate, and the boundary layer directly transitions to a turbulent state.

Optimal grain size distribution in gradient nano-grained nickel

Gradient nano-grained (GNG) metals are a unique class of metallic materials by manipulating the gradient size distribution, but the optimal grain size distribution producing the best strength–ductility synergy is still unclear. Here, the mechanical behavior and deformation mechanism of GNG Ni with different spatial distribution of grain size varying in the inverse Hall-Petch regime are investigated by molecular dynamics method. The results show that the GNG structure has the optimal strength–ductility synergy when the distribution of grain size gradient satisfies a linear relationship (i.e. the gradient rate n = 1). The strengthening and toughening mechanisms of the optimal GNG structure are further illustrated. It is found that the stress gradient and strain gradient in the GNG Ni with gradient rate n = 1 are the largest among different gradient structures. The optimal strength-ductility synergy in GNG structures with linear distribution of grain size is attributed to the remarkable enhancement of dislocations and the diminution of GB activities. These results would provide an insight into the mechanical performance tuning of GNG structures experimentally.

High-Quality SiO2/O-Terminated Diamond Interface: Band-Gap, Band-Offset and Interfacial Chemistry.

Silicon oxide atomic layer deposition synthesis development over the last few years has open the route to its use as a dielectric within diamond electronics. Its great band-gap makes it a promising material for the fabrication of diamond-metal-oxide field effects transistor gates. Having a sufficiently high barrier both for holes and electrons is mandatory to work in accumulation and inversion regimes without leakage currents, and no other oxide can fulfil this requisite due to the wide diamond band-gap. In this work, the heterojunction of atomic-layer-deposited silicon oxide and (100)-oriented p-type oxygen-terminated diamond is studied using scanning transmission electron microscopy in its energy loss spectroscopy mode and X-ray photoelectron spectroscopy. The amorphous phase of silicon oxide was successfully synthesized with a homogeneous band-gap of 9.4 eV. The interface between the oxide and diamond consisted mainly of single- and double-carbon-oxygen bonds with a low density of interface states and a straddling band setting with a 2.0 eV valence band-offset and 1.9 eV conduction band-offset.

Performance Perspective of Gate-All-Around Double Nanosheet CMOS Beyond High-Speed Logic Applications

In this review paper, the performance characteristics of Gate-All-Around (GAA) double nanosheet (NS) MOSFETs are described over a broad temperature range, from 78 K to 473 K (200 oC). Emphasis is on the analog operation, showing good potential. Besides the transistor length, the impact of the metal gate Effective Work Function and the vertical distance between the nanosheets has been studied. Among others, a clear Zero Temperature Coefficient (ZTC) gate voltage has been observed that can be modeled by considering the shift with temperature of the threshold voltage and the maximum transconductance. A trade-off has been noticed between the transistor efficiency and the unit gain frequency, whereby the optimal operation point occurs in strong inversion regime. The feasibility of designing simple analog circuits has also been demonstrated. Finally, a detailed investigation of the low-frequency noise behavior yields good values for the flicker noise Power Spectral Density in comparison with other technology nodes.

Topological Melting of the Metastable Skyrmion Lattice in the Chiral Magnet Co9Zn9Mn2

AbstractIn a β‐Mn‐type chiral magnet Co9Zn9Mn2, it is demonstrated that the magnetic field‐driven collapse of a room temperature metastable topological skyrmion crystal (SkX) passes through a regime described by a partial topological charge inversion. Using Lorentz transmission electron microscopy, the magnetization distribution is observed directly as the magnetic field is swept antiparallel to the original skyrmion core magnetization, that is, negative magnetic fields. Due to the topological stability of skyrmions, a direct transition of the metastable SkX to the equilibrium helical state is avoided for increasingly negative fields. Instead, the metastable SkX gradually transforms into giant magnetic bubbles separated by 2π domain walls. Eventually these large structures give way to form a near‐homogeneously magnetized medium that unexpectedly hosts a low density of isolated skyrmions with inverted core magnetization, and thus a total topological charge of reduced size and opposite sign compared with the initial state. A similar phenomenon has been observed previously in systems hosting ordered lattices of magnetic bubbles stabilized by the dipolar interaction and called “topological melting.” With support from numerical calculations, it is argued here that the observed regime of partial topological charge inversion has its origin in the topological protection of the starting metastable skyrmion state.

(Invited) Investigating Defects in the High-k/Ingaas System at Cryogenic Temperature

III-V RF devices operating at cryogenic temperature are highly desirable for application areas such as space communication or quantum computing. In the case of quantum computation, integration of the readout and control electronics close to the quantum bit (Qubit) stage is needed to allow scaling of the number of Qubits needed for practical applications. Many characteristics of high frequency operation at cryogenic temperature in novel III-V devices are not fully understood. In this study, we will focus on the behaviour of defects at or near the interface between the high dielectric constant (high-k) oxide and InGaAs semiconductor at cryogenic temperature and how it may affect the full device operation at low temperature.The thermal budget constraints associated with the processing III-V semiconductor devices prohibit the use of high temperature thermal treatments to reduce oxide defect densities in the high-k. This leads to defective oxides presenting higher instability, variability, and degradation issues than in the Si/SiO2 system. The methods developed to investigate defects in the Si/SiO2 metal oxide semiconductor (MOS) system generally attribute the divergence in capacitance voltage (CV) and conductance voltage (GV) from the ideal CV and GV characteristics mostly to interface state defects (ITs) [1], which is not the case of the III-V MOS system. As a consequence, attempts to fit the multi-frequency CV and GV response of III-V MOS structures in the weak inversion regime, using interface states alone, cannot recreate the experimental data.In this study, we present an advanced MOS defects characterisation method capable of discerning between the contributions of oxide defects (sometimes labelled ‘border traps’) and ITs. The method relies on the fully physics based simulation of MOS systems, including inelastic tunnelling from the semiconductor to localized defects in the oxide [2] to reproduce the experimental multi-frequency CV and GV characteristics. The simulations include physical models accurately describing the carrier capture/emission processes by oxide traps, and which incorporate tunneling into the dielectric in conjunction with lattice relaxation at the interface/border trap sites [3, 4]. The results will show that the simulations are able to reproduce the room temperature experimental data (both CV and GV) of InGaAs/Al2O3 MOS structures in all bias regions. This new method enables the precise extraction of the density, energy and spatial distribution away from the interface of electrically active oxide defects from different experimental results.Results will also be presented showing how the multi-frequency CV and GV response of n-InGaAs/Al2O3 and p-InGaAs/Al2O3 MOS structures change with reducing temperature. Measurements at 223K show a marked reduction in the CV and GV dispersion with frequency in the accumulation and depletion regions, consistent with a phonon assisted tunnelling interaction of electrons and holes with defects in the Al2O3. Reduction in the measurement temperature to 10K still demonstrates a residual dispersion of the capacitance and conductance with frequency, which is more marked in the case of the p-InGaAs/Al2O3 MOS structure. The models and trap distributions extracted from room temperature will be applied to the reduced temperature measurements (233 K and 10 K) to investigate the validity of the models and to gain further understanding of defect behaviour and associated device implications at cryogenic temperatures.[1] E. H. Nicollian and J. R. Brews, “MOS Physics and Technology,” John Wiley & Sons, New York, 1982.[2] A. Palma, et al. Phys. Rev. B Condens. Matter Mater. Phys., 56 (15), pp. 9565-9574 (1997).[3] E. Caruso, et al. IEEE Trans. Electron Devices, 67 (10), pp. 4372-4378 (2020)[4] G. Sereni, et al. “IEEE Trans. Electron Devices, vol. 62, no. 3, pp. 705–712, (2015).