The role of electronic energy loss in SHI irradiated Ni/oxide/n-GaP Schottky diode

The impact of energy loss mechanism by 100 MeV Au^8 + ion on the dielectric parameters of Ni/oxide/n-GaP Schottky diode was studied under different fluences. The Schottky barrier height, donor ion concentration and interface states density of the diode were varied considerably under different ion fluence. The various dielectric parameters were altered significantly by the ion fluence. The reduction in dielectric constant after irradiation was ascribed to screening of space charge polarization due to reduction in interface states density. The relaxation peak of imaginary electric modulus indicates hopping type conduction mechanisms in the intermediate voltage range. The sensitive behavior of dielectric parameters with fluence dose was attributed to the alteration of interface state density due to high electronic energy loss of 100 MeV Au^8 + ions at the interface.     

Bias-dependent small-signal parameters of Schottky contact microstrip lines

Schottky contact lines are a type of microstrip on semiconducting substrata. The strip forms a rectifying metal-semiconductor interface, the Schottky contact. Schottky contact lines show interesting small-signal and large-signal properties, so far unknown in microwave IC-technology, due to the voltage-dependent capacitance per unit length.In this paper the small-signal transmission line properties are investigated. Formulas for the characteristic impedance and the propagation constant are given. Particular account is taken of the effect of varying external d.c. bias. measurements performed on microstrip lines with Al- and Au-Schottky contacts on n-type silicon are given.     

Investigation of Ti-Ge/GaAs Schottky barrier contacts

The effect of germanium content in a titanium film, as well as treatment methods and conditions, on the Schottky barrier height (φ_b) and the ideality factor (n) for Ti-Ge / GaAs contacts were investigated. It is shown that photon treatment provides better contacts than thermal treatment.     

Displacement current of Au/p-diamond Schottky contacts

In this study, the displacement current of Au/p-diamond Schottky contacts was studied by comparing them with low-Mg-doped p-GaN Schottky contacts. In the current–voltage (I–V) characteristics, the current was proportional to the voltage sweep speed at V >−1.5 V. The differential output waveform was obtained through AC operation. Therefore, the displacement current was dominant in the low voltage region where in the true current was extremely small due to the large Schottky barrier height of 1.57 eV. The memory effect, due to the charge and discharge of localized acceptor-type deep-level defects, was negligible in the I–V curve. A clear AC differential signal was confirmed. This suggested that the interface defect density of the p-diamond contacts was very small compared to the p-GaN contacts. Hence, p-diamond Schottky contacts were expected to be a good candidate for a key device such as a phase modulator in a wireless transmitter.     

Calculations and measurements of contact resistance of semi-transparent Ni/Pd contacts to p-GaN

Calculations of specific contact resistance as a function of doping and barrier height were performed for p-type GaN. These calculations took into account two valence bands, each with different effective masses, and show that at low doping, the heavy hole band accounts for most of the conduction, whereas at heavier doping, the light hole band dominates conduction. These calculations also indicate the barrier height for typical contacts to p-GaN is between 0.75 eV and 1 eV. Specific contact resistance measurements were made for oxidized Ni/Au, Pd, and oxidized Ni/Pd ohmic contact metal schemes to p-GaN. The Ni/Pd contact had the lowest specific contact resistance, 6×10⁻⁴ Ω cm². Auger sputter depth profile analysis showed some Ni diffused away from the GaN surface to the contact surface with the bulk of the Pd located in between two areas of Ni. Both Ni and Pd interdiffused with the GaN at the semiconductor surface. The majority of the oxygen observed was with the Ni as NiO. Angle-resolved-x-ray photoelectron spectroscopy (AR-XPS) analyses showed the formation of predominantly NiO and PdO species, with higher Ni and Pd oxides at the contact surface.     

The electrical characteristics of Al/p-InP Schottky contacts

In this study, it has been investigated the electrical characteristics of identically prepared Al/p-InP Schottky diodes. The barrier heights (BHs) and ideality factors of all devices have been calculated from the electrical characteristics. Although the diodes were all identically prepared, there was a diode-to-diode variation: the effective barrier heights ranged from 0.83 ± 0.01 to 0.87 ± 0.01 eV, and the ideality factors ranged from 1.13 ± 0.02 to 1.21 ± 0.02. The barrier height vs. ideality factor plot has been plotted for the devices. Lateral homogeneous BH was calculated as a value of 0.86 eV from the observed linear correlation between BH and ideality factor, which can be explained by laterally inhomogeneities of BHs. The values of barrier height and free carrier concentration yielded from the reverse bias capacitance-voltage (C-V) measurements ranged from 0.86 ± 0.04 to 1.00 ± 0.04 eV and from (3.47 ± 0.39) × 10¹⁷ to (4.90 ± 0.39) × 10¹⁷ cm⁻³, respectively. The mean barrier height and mean acceptor doping concentration from C-V characteristics have been calculated as 0.91 eV and 3.99 × 10¹⁷ cm⁻³, respectively.     

ITO/HgInTe肖特基的光电特性

碲铟汞Hg3In2Te6是(In2Te3)x-(Hg3Te3)1-x(x=0.5)的化合物,被称为缺陷相化合物.在表面运用透明电极可以得到很高的量子效率.为了克服形成肖特基后漏电流过大的影响,运用等离子增强化学气相沉积在碲铟汞表面形成氧化层.运用直流平面磁控溅射技术和热电子蒸发技术分别在单晶HgInTe表面形成了ITO(SnO2 In2O3)/HgInTe和In/HgInTe接触,利用I-V测试仪对其I-V特性进行测量,运用能带结构和异质结理论对测量的,I-V结果进行了描述,测量结果符合热电子发射理论.结果表明:ITO/HgInTe形成具有整流特性的肖特基接触,通过计算得到了ITO/HglnTe的肖特基势垒高度为0.506 eV,理想因子n为3.2,串联电阻Rs为2 600 Ω;In/HgInTe形成欧姆接触.并且发现了在波长1.55 μm处有很好的响应光谱,同时室温下峰值探测率D*λ达到了1011cm·Hz1/2·W-1.     

On the ohmicity of Schottky contacts

The conditions under which Schottky contacts become ohmic are analyzed. Proceeding from classical concepts of the mechanisms of current flow, a generalized Schottky contact model is investigated. This model takes into account the thermionic current of majority charge carriers and the recombination current of minority carriers in Schottky contacts with a dielectric gap. Based on an analysis of the predictions of this model, ohmicity criteria are obtained for Schottky contacts and the conditions for a low injection level and the ohmicity of Si-based Schottky contacts are compared. It is shown that the conditions for Schottky-contact ohmicity do not coincide with those for p–n junctions.     

Characteristics of LPCVD WSi2/n-Si Schottky contacts

Detailed current-voltage and capacitance-voltage characteristics of low-pressure chemical vapor deposited (LPCVD) WSi₂/n-Si Schottky contacts are reported in the temperature range of 21 to 170°C. The diode ideality factor n was found to decrease from a value of 1.46 to 1.15 as temperature was increased. Schottky barrier height φ_B, on the other hand, was found to increase from 0.72 to 0.86 V with temperature. These results suggest that diode characteristics are affected by surface and bulk effects, especially at lower temperatures. High-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy analyses revealed isolated regions of oxynitride at the silicide/silicon interface that are predominantly located where silicide grain boundaries intersect the silicon surface     

Sputtering of Ni/Ti/SiC ohmic contacts

The presented work describes the behaviour of contact structures of Ni/Ti type on 6H-SiC n-type prepared by the sputtering technology. Simultaneous deposition of Ni and Ti is better. Plasma cleaning improves adhesion of metals; however, contact resistivity is worse. The Ni(50)/Ti(th)-type metallization has the best electrical parameters at the titanium layer thickness of 100 nm. The XPS analysis shows that the annealing reactions consume about 75 nm or 120 nm of SiC in the case of the Ni + Ti or the Ni/Ti metallization, respectively.     

I-V characteristics of Schottky contacts based on quantum wires

In this paper we derive the I-V characteristics of Schottky contacts based on bulk metal to semiconductor quantum wires interfaces. The obtained results show that quantum confinement is a strong reduction of the reverse saturation current when compared to conventional Schottky contacts. Numerical simulations are carried out to highlight the advantages of using these proposed heterodimensional interfaces in applications involving low-noise photodetectors and low-leakage gate electrodes.     

Barrier height temperature coefficient in ideal Ti/n-GaAs Schottky contacts

We have measured the I-V characteristics of Ti/n-GaAs Schottky barrier diodes (SBDs) in the temperature range of 60-320 K by the steps of 20 K. The SBDs have been prepared by magnetron DC sputtering. The ideality factor n of the device has remained almost unchanged between 1.02 and 1.04 from 120 to 320 K, and 1.10 at 100 K. Therefore, it has been said that the experimental I-V data are almost independent of the sample temperature and quite well obey the thermionic emission (TE) model at temperatures above 100 K. Furthermore, the barrier height (BH) Φ_b0 slightly increased with a decrease in temperature, 320-120 K. The Φ_b0 versus temperature plot from intercepts of the forward-bias ln I versus V curves has given a BH temperature coefficient of α = −0.090 meV/K. The Norde’s function has been easily carried out to determine the temperature-dependent series resistance values because the TE current dominates in the I-V characteristics. Therefore, the Φ_b0 versus temperature plot from the Norde’s function has also given a BH temperature coefficient value of α = −0.089 meV/K. Thus, the negligible temperature dependence or BH temperature coefficient close to zero has been attributed to interface defects responsible for the pinning of the Fermi level because their ionization entropy is only weakly dependent on the temperature.     

Ni，Ti/4H-SiC肖特基势垒二极管

采用本实验室生长的4H-SiC外延片,分别用高真空电子束蒸Ni和Ti做肖特基接触金属,Ni合金作欧姆接触,SiO_2绝缘环隔离减小高压电场集边效应等技术,制作出4H-SiC肖特基势垒二极管(SBD)。该器件在室温下反向击穿电压大于600 V,对应的漏电流为2.00×10~(-6)A。对实验结果分析显示,采用Ni和Ti作肖特基势垒的器件的理想因子分别为1.18和1.52,肖特基势垒高度为1.54 eV和1.00 eV。实验表明,该器件具有较好的正向整流特性。     

Forward I-V characteristics of Pt/n-GaAs Schottky barrier contacts

The forward I-V characteristics of Pt/n-GaAs planar Schottky diodes and the effect of high temperature annealing on these characteristics have been investigated. Near-ideal (thermionic emission theory) I-V characteristics with an ideality factor n ≈ 1·00–1·09 and a barrier height φ_B ≈ 0·90–0·95 V are obtained for diodes made on as-received GaAs. On annealing at 350°C in vacuum, n remains practically unchanged although φ_B increases by ≈ 5–6 per cent and rather large currents are detected at voltages <0·3 V, which are attributed to the recombination centers created during alloying.For diodes made on GaAs which was preannealed in air at 350°C, non-ideal behavior is observed with φ_B ≈ 0·79–0·80 V and n ≈ 1·29. After annealing at 350°C in vacuum, n gradually decreases to 1·07 whereas φ_B increases to 0·96 V. Recombination currents are now observed at lower voltages. After further annealing at 350°C in air, n increases, φ_B decreases and recombination currents at lower voltages are no longer observed. A mechanism is proposed to explain the observed forward I-V characteristic behavior.     

Au/Ge/Ni ohmic contacts to n-Type InP

The relationship between the electrical properties and microstructure for annealed Au/Ge/Ni contacts to n-type InP, with an initial doping level of 10¹⁷ cm^-3, have been studied. Metal layers were deposited by electron beam evaporation in the following sequence: 25 nm Ni, 50 nm Ge, and 40 nm Au. Annealing was done in a nitrogen atmosphere at 250-400‡C. The onset of ohmic behavior at 325‡C corresponded to the decomposition of a ternary Ni-In-P phase at the InP surface and the subsequent formation of Ni₂P plus Au₁₀In₃, producing a lower barrier height at the InP interface. This reaction was driven by the inward diffusion of Au and outward diffusion of In. Further annealing, up to 400‡C, resulted in a decrease in contact resistance, which corresponded to the formation of NiP and Au₉ln₄ from Ni₂P and Au₁₀In₃,respectively, with some Ge doping of InP also likely. A minimum contact resistance of 10^-7 Ω-cm² was achieved with a 10 s anneal at 400‡C.     

InP Schottky contacts with increased barrier height

We present an analysis of Schottky barriers in n-InP made by incorporating a thin native oxide. An oxidation technique using nitric acid under illumination produces an oxide layer with uniform composition distribution within the layer. The growth rate is interpreted as being partially limited by diffusion presumably of oxygen through oxide. The Au Schottky barrier formed on a 40–80 Å thick oxide layer exhibits little degradation of the ideality factor n (1.04 < n < 1.10) and an increase of the barrier height by greater than 0.3 eV, resulting in at least a 10^?4 times smaller reverse leakage current density, compared with conventional Au-InP barriers. The barrier height increase is analysed by a generalised model, and is found to be produced by the existence of fixed negative charges in the oxide layer. From the present analysis, a surface state density of 6.0 × 10¹² cm^?2 eV^?1 and an equivalent surface density of negative charges of 2.8 × 10¹² cm^?2 are determined independently. The origins of these, particularly of the surface states, are considered in relation to the P vacancies at the oxide-InP interface.     

GaAs surface plasma treatments for Schottky contacts

The properties of different rectifying metallizations (Al, Ti/Pt, WN_x) on GaAs have been investigated for various surface preparation procedures. In particular, in situ hydrogen plasma treatments were used to remove residual surface contamination (mainly O and C) and a nitrogen plasma to grow a thin mixed nitride layer. Al and Ti/Pt Schottky diodes with an ideality factor very close to 1, but with reduced barrier height, were found after the H₂ plasma as a consequence of H diffusion into GaAs. The Schottky barrier height was further reduced if a H₂ + N₂ plasma was performed. The N content in the sputtering environment during the WN_x deposition affects the diode properties of plasma-treated WN_x contacts. By increasing the N₂ partial pressure, the diode barrier height is reduced, probably due to nitridization of the GaAs surface. Such differences disappear after annealing the diodes in arsine overpressure at 800°C. WN_x contacts deposited under different conditions on H₂ plasma treated substrates also show a similar Schottky barrier height after such annealing.     

Au/Pt/Ti/Ni ohmic contacts to p-ZnTe

Ohmic contacts of Au/Pd/Ti/Ni to p-ZnTe show a minimum specific contact resistance of 10^-6 Ωcm² for a p-type doping level of 3×10¹⁹ cm^-3 and at an annealing temperature of 300°C. The Ni and Ti layers are very effective in improving the electrical properties of these contact