Thermally annealed Ni/n-GaAs(Si)/In Schottky barrier diodes

We have identically prepared as many as eight Ni/n-GaAs/In Schottky barrier diodes (SBDs) using an n-type GaAs substrate with a doping density of about 7.3 × 10¹⁵ cm⁻³. The thermal stability of the Ni/n-GaAs/In Schottky diodes has been investigated by means of current-voltage (I-V) techniques after annealed for 1 min in N₂ atmosphere from 200 to 700 °C. For Ni/n-GaAs/In SBDs, the Schottky barrier height Φ_b and ideality factor n values range from 0.853 ± 0.012 eV and 1.061 ± 0.007 (for as-deposited sample) to 0.785 ± 0.002 eV and 1.209 ± 0.005 (for 600 °C annealing). The ideality factor values remained about unchanged up to 400 °C annealing. The I-V characteristics of the devices deteriorated at 700 °C annealing.     

Controlling of electronic parameters of GaAs Schottky diode by poly(3,4-ethylenedioxithiophene)-block-poly(ethylene glycol) organic interlayer

The electronic properties of metal-organic semiconductor-inorganic semiconductor structure between GaAs and poly(3,4-ethylenedioxithiophene)-block-poly(ethylene glycol) organic film have been investigated via current-voltage and capacitance-voltage methods. The Au/PEDOT/n-GaAs contact exhibits a rectification behavior with the barrier height of 0.69 eV and ideality factor value of 3.94. The barrier height of the studied diode (0.67 eV) is lower than that of Ni/n-GaAs/In (0.85 eV) and Au/n-GaAs/In Schottky diodes. The decrease in barrier height of Au/n-GaAs/In Schottky diode is likely to be due to the variation in the space charge region in the GaAs. The obtained results indicate that control of the interfacial potential barrier for metal/n-GaAs diode was achieved using thin interlayer of the poly(3,4-ethylenedioxithiophene)-block-poly(ethylene glycol).     

Effect of annealing temperature on the electrical characteristics of Platinum/4H-SiC Schottky barrier diodes

Pt/4H-SiC Schottky barrier diodes have been fabricated to investigate the effect of annealing on the electrical characteristics of the fabricated devices. The parameters such as barrier height, ideality factor and donor concentration were deduced from the current–voltage (I–V) and the capacitance–voltage (C–V) measurements at room temperature. Diodes showed non-ideal behaviour like high value of ideality factor and lower value of barrier height. A barrier height of 1.82?eV was obtained from C–V measurements and it was 1.07?eV when obtained from the I–V measurements with ideality factor 1.71 for as-deposited diodes at room temperature. The diodes, therefore, were annealed in the temperature range from 25°C to 400°C to observe the effect of annealing temperature on these parameters. Schottky barrier height and ideality factors were found to be temperature-dependent. After rapid thermal annealing upto 400°C, a barrier height of 1.59?eV from C–V measurements and the value of 1.40?eV from I–V measurements with ideality factor 1.12 were obtained. Barrier heights deduced from C–V measurements were consistently larger than those obtained from I–V measurements. To come to terms with this discrepancy, we re-examined our results by including the effect of ideality factor in the expression of the barrier height. This inclusion of ideality factor results in reasonably good agreement between the values of barrier height deduced by the above two methods. We believe that these improvements in the electrical parameters result from the improvement in the quality of interfacial layer.     

Improved Ni Schottky Contacts on <Emphasis Type="Italic">n</Emphasis>-Type 4H-SiC Using Thermal Processing

High-temperature processing was used to improve the barrier properties of three sets of n-type 4H-SiC Schottky diodes fabricated with Ni Schottky contacts. We obtained an optimum average barrier height of 1.78 eV and an ideality factor of 1.09 using current–voltage measurements on diodes annealed in vacuum at 500°C for 24 h. Nonannealed contacts had an average barrier height of 1.48 eV and an ideality factor of 1.85. The Rutherford backscattering spectra of the Ni/SiC contacts revealed the formation of a nickel silicide at the interface, accompanied by a substantial reduction in oxygen following annealing.     

退火温度对Au/Ti/4H-SiC肖特基接触特性的影响

采用电子束蒸发法在4H-SiC表面制备了Ti/Au肖特基电极,研究了退火温度对Au/Ti/4H-SiC肖特基接触电学特性的影响.对比分析了不同退火温度下样品的电流密度-电压(J-V)和电容-电压(C-V)特性曲线,实验结果表明退火温度为500℃时Au/Ti/4H-SiC肖特基势垒高度最大,在.J-V测试和C-V测试中分别达到0.933 eV和1.447 eV,且获得理想因子最小值为1.053,反向泄漏电流密度也实现了最小值1.97×10-8 A/cm2,击穿电压达到最大值660 V.对退火温度为500℃的Au/Ti/4H-SiC样品进行J-V变温测试.测试结果表明,随着测试温度的升高,肖特基势垒高度不断升高而理想因子不断减小,说明肖特基接触界面仍然存在缺陷或者横向不均匀性,高温下的测试进一步证明肖特基接触界面还有很大的改善空间.     

The Cu/n-GaAs schottky barrier diodes prepared by anodization process

The metal-insulating semiconductor (MIS) Cu/n-GaAs diodes with thin anodic-insulating layer, which is formed by anodic oxidazation on the n-GaAs substrate in aqueous 4C₂H₆O₂+2H₂O+0.1H₃PO₄ electrolyte with pH=2.02; anodically untreated control Cu/n-GaAs diodes; and anodically treated Cu/n-GaAs diodes (several steps of anodization in the same electrolyte followed by a dip in diluted aqueous HCl solution and a subsequent rinse in deionized water) have been prepared. The anodization has increased the barrier heights as well as the ideality factors. We have obtained barrier heights of approximately 0.68 eV, 0.90 eV, and 0.92 eV for the control sample, anodically treated sample, and MIS sample, respectively, adding the contribution caused by image-force effect only. Thus, the barrier height has been increased by at least 140 meV. Furthermore, we have calculated a mean tunneling-barrier height of x=0.025 eV for the MIS Cu/n-GaAs Schottky barrier diode (SBD).     

Compositional dependence of thermal stability of refractory metal silicide schottky contacts to GaAs

Thermal stability of refractory metal silicide Schottky contacts, WSi_x, TaSi_x and MoSi_x withx = 0.6 andx = 2, to GaAs have been studied. It was found that the outdiffusion of Ga and As through the silicide films depends on the silicide composition, with much higher diffusion rate in films withx = 2 than in films withx = 0.6 and, therefore, contributes to the degradation of the Schottky barriers after high temperature anneal-ing.     

The influence of high-temperature annealing on SiC schottky diode characteristics

The influence of high temperature (up to 800C) annealing on the current-voltage characteristics of n-type 6H-SiC Schottky diodes is presented. Our experimental results indicate that high-temperature annealing can result in the improvement of the forw ard and reverse electrical characteristics of SiC Schottky diodes by repairing any leaky low barrier secondary diode parallel to the primary diode that may be present due to the barrier inhomogeneities at the Schottky contact interface.     

Correlation of microstructure with electrical behavior of Ti/GaN schottky contacts

We correlate structural and electrical characteristics of as-deposited and low-temperature annealed Ti contacts on GaN. Temperature dependent currentvoltage measurements are used to determine the effective barrier heights of the respective contacts, while high-resolution transmission electron microscopy is utilized for structural characterization. As-deposited Ti contacts are slightly rectifying with an effective barrier height of ∼200 meV. After annealing at 230°C, the barrier height increases to values of ∼450 meV. A similar behavior of Schottky contacts with more strongly rectifying diodes upon low-temperature annealing is observed for Zr metal contacts on GaN. As-deposited Ti already forms a thin TiN layer at the GaN interface. After annealing at 230°C, the average thickness and the distribution of TiN grains remain practically unchanged, but the interface with GaN roughens. We correlate the observed barrier height changes with interface roughness and phase formation and we discuss the results in terms of interface damage and the Schottky-Mott theory.     

JTE结构4H-SiC肖特基二极管的研究

借助半导体仿真软件Silvaco,仿真一种具有结终端扩展（JTE）结构的碳化硅（SiC）肖特基二极管（SBD）。其机理是通过JTE结构降低肖特基结边缘的电场集中效应,从而优化肖特基二极管的反向耐压能力。研究JTE区深度、宽度及掺杂浓度对碳化硅肖特基二极管的反向耐压的影响。通过优化结终端结构的结构参数使碳化硅肖特基二极管的反向耐压特性达到更好的性能要求。     

Ta/Si Schottky diodes fabricated by magnetron sputtering technique

Electrical properties of Ta/n-Si and Ta/p-Si Schottky barrier diodes obtained by sputtering of tantalum (Ta) metal on semiconductors have been investigated. The characteristic parameters of these contacts like barrier height, ideality factor and series resistance have been calculated using current voltage (I-V) measurements. It has seen that the diodes have ideality factors more than unity and the sum of their barrier heights is 1.21 eV which is higher than the band gap of the silicon (1.12 eV). The results have been attributed the effects of inhomogeneities at the interface of the devices and native oxide layer. In addition, the barrier height values determined using capacitance-voltage (C-V) measurements have been compared the ones obtained from I-V measurements. It has seen that the interface states have strong effects on electrical properties of the diodes such as C-V and R_s-V measurements.     

Electrical characteristics of high performance Au/n-GaN schottky diodes

Au/n-GaN Schottky diodes with the Au electrode deposited at low temperature (LT=77K) have been studied. In comparison, the same chip of GaN epitaxial layer was also used for room temperature Schottky diodes. The low temperature Schottky diodes exhibit excellent performance. Leakage current density as low as 2.55×10⁻¹¹ A·cm⁻² at −2.5 V was obtained in the LT Schottky diodes. The linear region in the current-voltage curve at forward bias extends more than eight orders in current magnitude. Current-voltage-temperature measurements were carried out to study the characteristics of the LT Schottky diodes. A typical barrier height of about 1.32 eV for the LT diode, which is the highest value ever reported, was obtained. The obvious enhancement in electrical performance makes the LT processing a very promising technique for GaN device application although the detailed mechanisms for the LT Au/n-GaN Schottky diodes are still under investigation.     

Electrical parameters of a DC sputtered Mo/n-type 6H-SiC Schottky barrier diode

A Mo/n-type 6H-SiC/Ni Schottky barrier diode (SBD) was fabricated by sputtering Mo metal on n-type 6H-SiC semiconductor. Before the formation of Mo/n-type 6H-SiC SBD, an ohmic contact was formed by thermal evaporation of Ni on n-type 6H-SiC and annealing at 950 °C for 10 min. It was seen that the structure had excellent rectification. The electrical parameters were extracted using its current–voltage (I–V) and capacitance–voltage (C–V) measurements carried out at room temperature. Very high (1.10 eV) barrier height and 1.635 ideality factor values were reported for Mo/n-type 6H-SiC using ln I–V plot. The barrier height and series resistance values of the diode were also calculated as 1.413 eV and 69 Ω from Norde׳s functions, respectively. Furthermore, 1.938 eV barrier height value of Mo/n-type 6H-SiC SBD calculated from C–V measurements was larger than the one obtained from I–V data.     

Extraction of electronic parameters of Schottky diode based on an organic Orcein

An Au/Orcein/p-Si/Al device was fabricated and the current-voltage measurements of the devices showed diode characteristics. Then the current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of the device were investigated at room temperature. Some junction parameters of the device such as ideality factor, barrier height, and series resistance were determined from I-V and C-V characteristics. The ideality factor of 2.48 and barrier height of 0.70 eV were calculated using I-V characteristics. It has been seen that the Orcein layer increases the effective barrier height of the structure since this layer creates the physical barrier between the Au and the p-Si. The interface state density N_ss were determined from the I-V plots. The capacitance measurements were determined as a function of voltage and frequency. It was seen that the values of capacitance have modified with bias and frequency.     

Fabrication and electrical characteristics of Schottky diode based on organic material

The current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of Al/Orange G/n-Si/AuSb structure were investigated at room temperature. A modified Norde’s function combined with conventional forward I-V method was used to extract the parameters including barrier height (BH) and the series resistance. The barrier height and series resistance obtained from Norde’s function was compared with those from Cheung functions, and it was seen that there was a good agreement between series resistances from both methods. The C-V characteristics were performed at 10 kHz and 500 kHz frequencies, and C-f characteristics were performed 0.0 V, +0.4 V and −0.4 V.     

Schottky enhancement of contacts to n-(In<Subscript>0.52</Subscript>Al<Subscript>0.48</Subscript>)As using PdAl as a metallization

PdAl was selected as a reactive contact to n-(In_0.52Al_0.48)As with the intention of forming a thin, AlAs-enriched interlayer of graded (In_1−xAl_x)As semiconductor alloy, following rapid thermal annealing. Selection of PdAl was based on the experimentally established existence of a quasi-reciprocal phase relationship. A Schottky barrier enhancement of 0.07 eV (measured by current-voltage (I-V)) and 0.09 eV (measured by capacitance-voltage (C-V)) was found following a 1-min anneal at 450°C. High-resolution transmission electron microscopy (HRTEM) examination showed the presence of an edge dislocation in the interlayer alloy, suggesting an enrichment of AlAs. Schottky barrier enhancement is in qualitative agreement with the prediction of the combined thermodynamic/kinetic model.     

肖特基二极管异常击穿特性曲线的研究

本文简述了肖特基二极管的原理,结构、性能特点,分析了生产中经常出现的异常击穿特性曲线,并提出了相应的改进措施.     

金属/氮化物肖特基势垒和欧姆接触研究进展

金属 /氮化物肖特基势垒和欧姆接触是蓝紫光光学器件及高温大功率电子器件中的关键工艺。氮化物半导体是一种极性材料 ,表面态密度较低 ,费米能级钉扎效应较弱 ,表面处理能显著影响接触特性。样品表面的沾污和氧化层也会使接触特性显著退化。宽禁带材料的杂质离化能高 ,重掺杂比较困难。深能级陷阱对载流子的俘获效应很强。这些因素都增加了接触的制作难度 ,促使人们寻求新的方案来改进接触特性。文中从金属 /半导体接触的物理模型出发来综述肖特基势垒和欧姆接触的研究进展 ,希望能给器件研究者提供新的思路。