Electron traps in MIS-type Schottky barriers on n-GaAs were investigated by measuring the change of the flat-band voltage, due to detrapping, as a function of time. The trap depth and the capture cross section for a particular trap were obtained from the temperature dependence of the time constant for detrapping. It was found that the detrapping process in some cases is a two-state thermionic emission and tunneling process. For other trapping levels the results indicated clearly that the mechanism was different from the thermionic emission and tunneling process. 相似文献
In this paper, the influence of two pre-evaporation surface treatments on the electrical characteristics of n- and p-Si/Au, Cr and Ti MIS diodes are studied. A strong dependence of the barrier height on the pre-evaporation treatment is observed and is found to be independent of the metal work function. In order to explain this, it is suggested that the interfacial charges are strongly affected by the pre-evaporation treatment used. 相似文献
The forward current-voltage (I-V) characteristics of polycrystalline CoSi2/n-Si(100) Schottky contacts have been measured in a wide temperature range. At low temperatures (≤200K), a plateau-like section is observed in the I-V characteristics around 10-4A·cm-2. The current in the small bias region significantly exceeds that expected by the model based on thermionic emission (TE) and a Gaussian distribution of Schottky barrier height (SBH). Such a double threshold behaviour can be explained by the barrier height inhomogeneity, i.e. at low temperatures the current through some patches with low SBH dominates at small bias region. With increasing bias voltage, the Ohmic effect becomes important and the current through the whole junction area exceeds the patch current, thus resulting in a plateau-like section in the I-V curves at moderate bias. For the polycrystalline CoSi2/Si contacts studied in this paper, the apparent ideality factor of the patch current is much larger than that calculated from the TE model taking the pinch-off effect into account. This suggests that the current flowing through these patches is of the tunnelling type, rather than the thermionic emission type. The experimental I-V characteristics can be fitted reasonably well in the whole temperature region using the model based on tunnelling and pinch-off. 相似文献
Magnetron-sputtered CoSi2 and TiSi2 Schottky barriers on n- and p-type GaP were investigated. Their hitherto unknown barrier heights were determined to be 0.98 eV (for CoSi2/n-GaP and CoSi2/p-GaP), 0.91 eV (for TiSi2/n-GaP), and 0.90 eV (for TiSi2/p-GaP). It was found that magnetron-sputtering induced a compensated layer near the surface, both for n- and p-type GaP, with a thickness of about 0.05 m. As the dependence of the shift of the Mott-Schottky intercept with the V-axis on the substrate dopant concentration obeyed some specific law, we proposed that the defects are neutral complexes of dopant ions and sputter-induced native defects. These native defects were assumed to depend on the Fermi level position, namely the PGa antisite and the VP vacancy for p-GaP and the VGa vacancy for n-GaP. The conversion between these defects occurs by nearest neighbour hopping of a phosphorus atom. The Schottky barrier heights obtained on p-GaP could be explained by Fermi level pinning at the surface due to the PGa defects. This could not be confirmed by n-GaP as the energy level position of the VGa was not available. The defects could be annealed out between 200° C and 300° C and the associated change of the Schottky barrier height corroborated the proposed model.On leave from the Université de Burundi, Faculté des Sciences, Bujumbura, Burundi 相似文献
The solid state reaction between a thin (30 nm) Ir film and different Si substrates (p-type Si(1 0 0), n- and p-type Si(1 1 1), silicon on insulator (SOI) and polycrystalline Si) was studied using a combination of in situ X-ray diffraction (XRD), in situ sheet resistance and laser light scattering measurements. No significant influence of either the dopants or the substrate orientation was detected as a phase formation sequence of IrSi, Ir3Si4,Ir3Si5 and IrSi3 was found for all samples. The presence of a thin (<4 nm) amorphous IrSi film at room temperature and its subsequent crystallization could be deduced from the appearance of a broad semi-amorphous diffraction peak in the XRD spectrum around 400 °C. The results were verified using ex situ Rutherford Backscattering Spectroscopy, Scanning Electron Microscopy and 4-point probe measurements on quenched samples. The activation energy of the crystallization process and the silicide growth was determined using a Kissinger analysis on ramp anneals with different ramp rates. In addition, the influence of up to 25 volumetric % (20.5 atomic %) of Ir to the silicide formation in the Ni/Si system was studied on SOI and polycrystalline Si substrates. In the presence of Ir, the temperature range over which the low resistivity NiSi exists, is reduced both through an increase in formation temperature and an earlier consumption by the formation of NiSi2. After the heat treatment, a continuous distribution of Ir throughout the NiSi2 phase was detected using X-ray photoelectron spectroscopy depth profiling. A low sheet resistance of was maintained on both substrates up to 900 °C. 相似文献
In this paper, we present a high data rate implementation of a digital predistortion (DPD) algorithm on a modern mobile multicore CPU containing an on-chip GPU. The proposed implementation is capable of running in real-time, thanks to the execution of the predistortion stage inside the GPU, and the execution of the learning stage on a separate CPU core. This configuration, combined with the low complexity DPD design, allows for more than 400 Msamples/s sample rates. This is sufficient for satisfying 5G new radio (NR) base station radio transmission specifications in the sub-6 GHz bands, where signal bandwidths up to 100 MHz are specified. The linearization performance is validated with RF measurements on two base station power amplifiers at 3.7 GHz, showing that the 5G NR downlink emission requirements are satisfied.