A new charge pumping method for determining the spatial interface state density distribution in MOSFETs

Determination of the density of Si-metal interface states and excess capacitance caused by them

Determination of interface state density in MOSFETs using the spatial profiling charge pumping technique

We have investigated the electrical properties of Ru/Ni/n-GaN Schottky structure using current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. The barrier height (Fbo) and ideality factor (n) of Ru/Ni/n-GaN Schottky structure are found to be 0.66 eV and 1.44, respectively. The Fbo and the series resistance (RS) obtained from Cheung's method are compared with modified Norde's method, and it is seen that there is a good agreement with each other. The energy distribution of interface state density (NSS) is determined from the I-V measurements by taking into account the bias dependence of the effective barrier height. Further, the interface state density NSS as determined by Terman's method is found to be 2.14´10 12 cm -2 eV -1 for the Ru/Ni/n-GaN diode. Results show that the interface state density and series resistance has a significant effect on the electrical characteristics of studied diode.

Investigation of diode parameters using I– V and C– V characteristics of In/SiO 2/p-Si (MIS) Schottky diodes

In this work, a set of LDD NMOS transistors are used as test structures for a modified charge pumping technique (LDD charge pumping) to directly measure the interface state density in the LDD region. The technique is validated by measurements on virgin samples and those subjected to hot carrier stress and Fowler-Nordheim stress, which are known to cause different amounts of degradation of the interface over the LDD region and that over the channel region. GIDL current measurements are shown to be in agreement with the charge pumping results. By combining the LDD charge pumping technique with gate to drain capacitance measurements, the lateral profile of the interface state density in the overlap region is obtained.

In this study, we have investigated the intersection behavior of the forward bias current–voltage (I–V) characteristics of the Al/TiO2/p-Si (MIS) structures in the temperature range of 100–300 K. The intersection behavior of the I–V curves appears as an abnormality when compared to the conventional behavior of ideal Schottky diodes and MIS structures. This behavior is attributed to the lack of free charge at a low temperature and in the temperature region, where there is no carrier freezing out, which is non-negligible at low temperatures, in particular. The values calculated from the temperature-dependent forward bias I–V data exhibit unusual behavior, where the zero-bias barrier height (ϕb0) and the series resistance (Rs) increase with increasing temperature. Such temperature dependence of ϕb0 and Rs is in obvious disagreement with the reported negative temperature coefficient. An apparent increase in the ideality factor (n) and a decrease in the ϕb0 at low temperatures can be attributed to the inhomogeneities of the barrier height, the thickness of the insulator layer and non-uniformity of the interfacial charges. The temperature dependence of the experimental I–V data of the Al/TiO2/p-Si (MIS) structures has revealed the existence of a double Gaussian distribution with mean barrier height values () of 1.108 eV and 0.649 eV, and standard deviations (σs) of 0.137 V and 0.077 V, respectively. Furthermore, the temperature dependence of the energy distribution of interface state density (Nss) profiles has been determined from forward bias I–V measurements by taking into account the bias dependence of the effective barrier height (ϕe) and n. The fact that the values of Nss increase with increasing temperature has been attributed to the molecular restructuring and reordering at the metal/semiconductor interface under the effect of temperature.

Transparent gate structures were fabricated by electron beam evaporation of Sn-doped In2O3 on oxidized p-Si substrates. The samples were oxidized at 1100°C in dry oxygen. No post-oxidation or post-electrode-deposition annealig was carried out. Admittance-voltage-frequency measurements were made under optical illumination. Interface state density distributions and hole and electron capture cross-sections were obtained using the recently developed optical metal-oxide-semiconductor (MOS) admittance technique. The experimental interface state density profile contained two peaked distributions, one near the valence band-edge Ev, and the other near the conduction band-edge Ec, overlying a concave background. The peak near Ec was sharper and the peak density was higher than in the case of the peak near Ev. The capture cross-section vs band-gap energy profile also displayed a peaked distribution for interface states under each of the peaks. With increasing illumination, the state density at the peak increased, the peak energy location moved closer to the respective band-edge, and the capture cross-section decreased. The experimental results show the presence of defects at unpassivated Si-SiO2 interfaces, which exchange electrons/holes with silicon bands under illumination.

The determination of the interface state density distribution of the Al/methyl red/p-Si Schottky barrier diode by using a capacitance method

A new method of measuring the density of band-gap interface states at the Si-SiO2 interface has been developed. This method is based on a charge pumping phenomenon and can be performed on a metal-oxide-semiconductor transistor structure without the need for Shockley–Hall–Read statistics. Although the method requires knowledge of the gate voltage-surface potential relationship, the measured density of states is not as sensitive to either errors or fluctuations in this relationship as other more common techniques. Other advantages of this new method are that it can measure the density of interface states over most of the band gap, it is relatively simple to implement, and has a resolution comparable to either the conductance or deep level transient capacitance techniques. Applying the new method to a transistor with a channel length of 50 μm and a width of 25 μm, the density of interface states has been measured to within 80 meV of the conduction band.

Current transport mechanism in Al/Si 3N 4/p-Si (MIS) Schottky barrier diodes at low temperatures

We demonstrate our new local deep level spectroscopy system improved for more accurate analysis of trap states at SiO2/4H-SiC interfaces. Full waveforms of the local capacitance transient with the amplitude of attofarads and the time scale of microseconds were obtained and quantitatively analyzed. The local energy distribution of interface state density in the energy range of EC − Eit = 0.31–0.38 eV was obtained. Two-dimensional mapping of the interface states showed inhomogeneous contrasts with the lateral spatial scale of several hundreds of nanometers, suggesting that the physical origin of the trap states at SiO2/SiC interfaces is likely to be microscopically clustered.

The interfacial density of states (Dit) distribution of high-κ dielectric Ga2O3(Gd2O3) [GGO] directly deposited on n-type Ge(100) without invoking any interfacial passivation layer (IPL) was established using conductance measurements and charge pumping (CP) technique. The conductance measurements yielded Dit values in the range of (1–4)×1011 cm-2 eV-1 from the mid-gap energy to the conduction band edge within the Ge band gap, which are consistent with the mean Dit value of ∼2×1011 cm-2 eV-1 near the mid-gap obtained independently by the CP method. The flat Dit distribution at the conduction band edge compares favorably with those attained using IPLs such as SiO2/Si-cap and GeO2.

Interface state density distributions and hole capture cross sections have been determined as a function of the energy for MOS structures made with anodic oxides on p-type GaSb by the ICTS (isothermal capacitance transient spectroscopy) technique. The interface state density increases towards the band edge from 3×1011 to 1×1012/cm2eV in the energy range of 0.3 to 0.03 eV above the valence band.

The effects of the time-dependent on the characteristic parameters of polypyrrole/ p-type Si/Al diode

Interface state densities, low frequency noise and electron mobility in surface channel In 0.53Ga 0.47As n-MOSFETs with a ZrO 2 gate dielectric