Increase In Trap Concentration Research Articles

Origin of exponentially large increase in the leakage current in alumina films depending on the ALD synthesis temperature

Amorphous aluminum oxide a-Al2O3 deposited by atomic layer deposition (ALD) is widely used in nonvolatile memory devices. In this paper, the leakage current dependence on the ALD synthesis temperature is investigated by six charge transport models: Schottky effect, thermally assisted tunneling at a contact, Frenkel effect, Hill-Adachi model of overlapping Coulomb potentials, Makram-Ebeid and Lannoo multiphonon isolated trap ionization model, and Nasyrov–Gritsenko model of phonon-assisted tunneling between neighboring traps. It is shown that the leakage current exponentially increases with the ALD synthesis temperature, which is related to the increase in trap concentration.

Влияние ловушек на накопление подвижного заряда в МОП-структурах при термополевых обработках

A quantitative model describing the influence of traps on the parameters of mobile charge migration in the gate dielectric of MOS structures is presented. The dependences of the effective diffusion coefficients and activation energy on trap accumulation, ion-trapping binding energy, impurity concentrations, and thermal field treatment temperatures are calculated. An increase in trap concentration was found to hamper mobile charge accumulation in the vicinity of the Si-SiO2 interface. The presented model can be used to explain the scattering of experimental data on sodium ion diffusion in silicon dioxide.

Effect of Acceptor Traps in GaN Buffer Layer on Breakdown Performance of AlGaN/GaN HEMTs.

In this paper, Silvaco TCAD software is used to simulate the buffer traps in AlGaN/GaN high electron mobility transistors (HEMTs), and its effects on the breakdown performance and key parameters of the devices are investigated by changing the position and concentration of the acceptor traps in the buffer layer. The results show that with the increase of trap concentration, the traps capture electrons and reduce the off-state leakage current, which can improve breakdown voltage of the devices. At the same time, as the trap concentration increases, the ionized traps make a high additional electric field near the drain edge, leading to the decrease of breakdown voltage. With the combined two effects above, the breakdown voltage almost ultimately saturates. When the source-to-gate (Access-S) region in the GaN buffer layer is doped alone, the minimum and most linear leakage current for the same trap concentrations are obtained, and the additional electric field has a relatively small effect on the electric field peak near the drain as the ionized traps are furthest from drain. All these factors make the breakdown voltage increase more controllably with the Access-S region doping, and it is a more potential way to improve the breakdown performance.

Deep insight into material-dependent DC performance of Fe DS-SBTFET and its noise analysis in the presence of interface traps

This paper reports the DC performance of Ferroelectric Dopant Segregated Schottky Barrier TFET (Fe DS-SBTFET) for different types of materials in the Dopant Segregated (DS) layer and its noise analysis considering the presence of Gaussian and uniform interface traps with the device being subjected to variation in ferroelectric thickness. Silicon doped HfO2 ferroelectric layer increases the tunneling junction electric field. Maximum ION/IOFF ratio of 1.2 × 109 and 14 mV/dec Subthreshold Swing (SS) have been achieved by using ferroelectric layer of thickness 6 nm. Different electrical parameters such as SS and ION/IOFF ratio have been explored for various trap concentrations. ON state current deteriorates with the increase in trap concentration. The dominancy of different noise components has been analysed with respect to frequency. Both flicker noise and generation-recombination noise contribute to the net noise at low frequency range. Flicker noise dominates at mid frequency and the major contribution at high frequency is of diffusion noise.

Mechanism of stress induced leakage current in Si3N4

In this paper, the experimental current density versus electric field characteristics of Si3N4 before and after the electrical field-induced stress were measured. It is shown that, the Frenkel model of Coulomb trap ionization, Hill-Adachi model of overlapping Coulomb traps, Makram-Ebeid and Lannoo multiphonon isolated trap ionization model do not describe the charge transport of Si3N4 before and after the electrical field-induced stress. The Nasyrov-Gritsenko model of phonon assisted tunneling between traps quantitatively describes the hole transport mechanism in Si3N4 before and after the induced stress at traps energies Wt = 1.6 eV and Wopt = 3.2 eV. The current leakage at different induced stresses in Si3N4 is explained by the increase of trap concentration via the creation of Si-Si bonds, which are traps in Si3N4.

Role of Fe impurity complexes in the degradation of GaN/AlGaN high-electron-mobility transistors

Recent experiments show that GaN/AlGaN high-electron-mobility transistors suffer from significant current collapse, which is caused by an increase in the concentration of traps with energy levels 0.5–0.6 eV below the conduction-band edge. This increase in trap concentration is consistent with thermally activated defect diffusion, but the responsible defect complexes have not been identified. It has been suggested that the defect complex may contain iron because of the proximity of the Fe-doped GaN substrate. Here, we report first-principles density-functional calculations of substitutional iron complexes, investigate their properties, and show that the FeGa-VN complex has properties that account for the observed degradation.

Mechanism of GeO2 resistive switching based on the multi-phonon assisted tunneling between traps

Model of evenly distributed traps in bulk dielectric is proposed for the resistive memory switching mechanism. Switching from high resistance to the low resistance state is explained by several-fold increase in trap concentration after the application of switching voltage. Both high and low resistance conductivities are governed by multi-phonon ionization and tunneling between neighboring traps. Thermal trap energy for oxygen vacancy and electron effective mass for crystal α-GeO2 were calculated using density functional theory and used for the fitting of our charge transport model of resistive memory. The model was verified on the TaN-GeO2-Ni structure with good semi-quantitative agreement with experiment.

Evaluation and Numerical Simulations of GaN HEMTs Electrical Degradation

In this letter, the effects of dc stress on GaN high-electron-mobility transistors' performance are investigated by means of experimental measurements and numerical simulation. A degradation of both dynamic (pulsed <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> ) and static characteristics (dc) has been observed on stressed devices, and it has been experimentally related to the formation of an electron trap in the AlGaN barrier layer. Numerical simulations carried out on the tested structure by introducing a trapping region at the gate edge of the device barrier confirm the experimentally observed device degradation. The worsening of the dynamic performance is induced by both an increase in trap concentration and/or depth of the trapping region while the degradation of the dc characteristics can be explained by an increase in the trapping-region depth.

Impact of Ga/N flux ratio on trap states in n-GaN grown by plasma-assisted molecular-beam epitaxy

The effect of growth regime on the deep level spectrum of n-GaN using molecular-beam epitaxy (MBE) was investigated. As the Ga/N flux ratio was decreased towards Ga-lean conditions, the concentration of two acceptor-like levels, at Ec−3.04 and 3.28 eV, increased from 1015 to 1016 cm−3 causing carrier compensation in these films. Thus, these two traps behaved as the dominant compensating centers in MBE n-GaN. Furthermore, the increase in trap concentration also strongly correlated with the degradation of both surface morphology and bulk electron mobility towards Ga-lean conditions, where higher pit densities and lower mobility were observed. These results show that the growth regime directly impacts all morphology, bulk transport, and trap states in n-GaN.

Effect of neutron irradiation on the electrical conductivity and current-voltage characteristics of PXZ1-xTx)O3 solid solution

The influence of defects introduced by fast neutron irradiation on the electric conductivity and current-voltage characteristics of Pb(Zr1-xTix)O3 solid solution is studied. It is found that defects cause a decrease in electric conductivity and an increase in activation energy. Moreover, a critical temperature is found upwards of which the PZT samples become sub-Ohmic in well defined ranges of external field strength. The introduction of defects broadens this field range and shifts it towards lower temperatures. These defect-induced changes are attributed not only to the increase in trap concentration but also to variations in energy distribution of the trap states.