Electrical characteristics of GaAsP Schottky barrier diodes

Schottky barrier diodes of chromium on n-type epitaxial gallium arsenide phosphide (GaAsP) were studied from 25°C to 440°C. The diodes showed significant rectification properties up to a temperature of 440°C. At high temperature the reverse leakage current was 1.15 mA at 25 V with a diode area of 1.14×10⁻³ cm² as compared with 0.25-μA current at room temperature. The n factor derived from the slope of the ln I vs. V curves was 1.1. The barrier height for chromium was found to be 1.25 eV from the capacitance measurements and 1.12 eV from the saturation current vs. temperature measurements. The slope of the C-V curves yielded a carrier concentration of 6.0×10¹⁵ carriers per cm³.     

On the current-voltage characteristics of epitaxial Schottky barrier diodes

The J-V characteristics of epitaxial Schottky barrier diodes are analyzed. Based on the assumption of negligible recombination in the epitaxial layer, formal solution from which the J-V characteristics can be calculated is derived. The solution is valid for all injection levels and reduces to the form I = I_s[exp (q(V?IR)/kT) ? 1], where R is the series resistance of the epitaxial layer, under C12 C12V low-injection conditions. The analysis is justified by very close correspondence with exact numerical calculations using the Finite Element Device Analysis Program (FIELDAY) in which thermionic emission boundary conditions are implemented for both electrons and holes. It is shown that for low barrier Schottky diodes the minority carrier injection is negligible and the expression I = I_s[exp (q(V?IR)/kT) ? 1] describes the I-V characteristics over large bias range. For high barrier C12 C12 V Schottky diodes the exact solution must be used as minority carriers are injected and the series resistance is decreased due to conductivity modulation effect.     

The effects of radiation damage on the properties of Ni-nGaAs Schottky diodes—II Terminal characteristics

The effects of radiation damage on the electrical characteristics of Ni-nGaAs Schottky diodes are studied, the damage being introduced by implanting various ions (B, O, He, Ge) into the depletion layer. Current-voltage characteristics show excess current flow after irradiation, this being explained in terms of a recombination-generation process. A trap assisted-tunnelling mechanism is also believed responsible for conduction in reverse bias for voltages greater than a few volts. Reverse voltage-capacitance measurements indicate the presence of a compensated layer within the depletion region which strongly affects the capacitance of deeply implanted diodes. For shallower implants, however, the capacitance becomes dominated by surface state effects at the interface. In forward bias the capacitance-voltage characteristics are very similar to those expected for a p-i-n structure, becoming more p-i-n like in behaviour as the damage is increased. Finally a model is proposed to explain the observed characteristics in terms of a change in the physical nature of the barrier region due to damage produced defect states.     

The effect of Ti:W barrier metal on characteristics of palladium-silicide Schottky barrier diodes

The values of diode-quality factor and reverse-current leakage of Au/Pd/Ti:W/Pd₂Si/nSi unguarded Schottky barrier diodes are much higher than expected from silicide/silicon junction-radius induced highfield effects. Experimental Ti-, W-, and Ti:W-MIS structures were built and tested to show that Ti is responsible for the formation of a parasitic Ti-MIS structure around the unguarded-diode perimeter. This parasitic structure is responsible for excessive current leakage and also for an additional unguarded-diode degradation induced by annealing at 400 °C.     

Current-voltage characteristics of Schottky barrier diodes withdynamic interfacial defect state occupancy

Schottky barrier diode theory conventionally assumes that the barrier height remains constant with the applied bias. However, high ideality factors and certain anomalous capacitance-voltage characteristics can only be explained by letting the barrier height vary with the applied voltage. Changes in the occupation of surface states have been inferred to be the cause of this change in barrier height, although the precise nature of these surface states has not yet been determined. This article examines the role of monoenergetic interfacial defect states whose occupancy is dynamically controlled by the local carrier densities, rather than by equilibrium conditions. Certain types of surface donor and acceptor states are shown to have a strong influence on the resulting current-voltage characteristics. The Al/GaAs(100) system is discussed in detail and experimental results are compared to this analytic model     

Argon-ion bombardment effects on the electrical characteristics of platinum-silicon Schottky diodes

Before barrier metal evaporation, silicon Schottky diodes were cleaned by argon-ion bombardment. Some device series were evaporated just after the ion cleaning, whereas others were annealed beforehand. The electrical characteristics of the different series were checked by means of standard I/V and C/V measurements. Whereas the ideality coefficient and the barrier height obtained from I/V characteristics showed nearly complete recovery after heat treatment for 1 h at 700°C, the barrier height from C/V measurements did not recover.     

Thermally oxidized mesa Schottky barrier diodes

Schottky barriers with a thermally oxidized mesa structure have been fabricated. The fabrication process is described. The mesa structure averts electric field crowding at the barrier periphery. The reverse diode characteristic shows a sharp breakdown at the voltage expected for an ideal, abrupt diode of semi-infinite extent and identical doping concentration.     

Gallium arsenide dual Schottky barrier diodes

Gallium arsenide diodes were made which had Schottky-barriers for both contacts. Devices which were too thick for space change reach-through to occur at breakdown showed microwave oscillations, while thin diodes did not oscillate. Additionally, the structures could be distinguished on the basis of the noise accompanying breakdown. The performance was analysed in terms of transistor theory in which there is avalanche multiplication in the collector space charge region. It was concluded that there is a smooth transition between the reachthrough breakdown characteristic of the BARITT and true avalanche breakdown. The nature of the breakdown depends on the base width and the emitter efficiency.     

Low-frequency noise in Schottky barrier diodes

The low-frequency excess noise in Schottky barrier diodes has been investigated. In the ideal case where the saturation current is completely determined by thermionic emission of electrons, no 1/? noise will be produced in the barrier. The presence of trap states in the depletion region can lead to generation-recombination noise. At sufficient high forward currents 1/? noise can be generated in the series resistance of the Schottky diode. Deviations from the ideal diode, for example as a result of edge effects, produce 1/? noise and increase at the same time the ideality factor. It is empirically found that the 1/? noise level decreases very rapidly if the ideality factor tends to unity.     

AuSiC Schottky barrier diodes

Results of the experimental study of Au n-type SiC Schottky barrier diodes at room temperature are presented. The diodes are fabricated by vacuum-evaporating gold on chemically etched n-type hexagonal (6H) SiC surfaces and exhibit excellent forward current vs voltage characteristics with the exponential factor n of about 1·07±0·02 for voltages between 0·35 and 0·85 V. The linear part of the characteristic, in a semi-logarithmic plot, extends over seven orders of magnitude in current. The forward current-voltage characteristics are found to agree quantitatively with the theory based on thermionic emission with the barrier height modified by image force lowering. The Schottky barrier height is determined from three independent techniques: differential capacitance vs voltage, photoresponse, and forward current vs voltage methods. The barrier height deduced from the three methods is about 1·40±0·05 V.     

基于肖特基二极管的太赫兹二倍频器设计

固态倍频器是太赫兹源应用中的关键器件,如何利用非线性器件提高太赫兹倍频器件的效率是设计太赫兹固态电路的关键。本文介绍了利用肖特基二极管非线性特性设计固态太赫兹二倍频器的2种方法,即采用直接阻抗匹配和传输模式匹配设计了2种不同拓扑结构的170 GHz二倍频器,针对设计的结构模型,分别进行三维有限元电磁仿真和非线性谐波平衡仿真。仿真结果表明,在17 dBm输入功率的驱动下,倍频器在160 GHz~180 GHz输出频率范围内,倍频效率在15%左右,输出功率大于7 mW。最后对2种方法设计的倍频器结构进行了简单对比和分析,为今后太赫兹倍频研究和设计提供仿真方法。     

Computer study on GaAs Schottky barrier IMPATT diodes

Oscillation characteristics of GaAs Schottky barrier IMPATT diodes are studied by computer simulation. For a Schottky barrier-n-n⁺ structure, the Read condition and the just-punch-through condition are found to be optimum with respect to the efficiency and power at 30 GHz. In order to improve the efficiency, a superabrupt doping profile is proposed and a high efficiency of 32 per cent is predicted. Calculation of the frequency dependence of the efficiency shows that GaAs IMPATT diodes still have the potentiality of high efficiency oscillator at 100 GHz and they are a promising microwave source in mm-wave region.     

Electrical characteristics and inhomogeneous barrier analysis of Au-Be/p-InSe:Cd Schottky barrier diodes

We have identically prepared Au-Be/p-InSe:Cd Schottky barrier diodes (SBDs) (21 dots) on the InSe:Cd substrate. The electrical analysis of Au-Be/p-InSe:Cd structure has been investigated by means of current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) measurements at 296 K temperature in dark conditions. The effective barrier heights and ideality factors of identically fabricated Au-Be/p-InSe:Cd SBDs have been calculated from their experimental forward bias current-voltage (I-V) characteristics by applying a thermionic emission theory. The BH values obtained from the I-V characteristics have varied between 0.74 eV and 0.82 eV with values of ideality factors ranging between 1.49 and 1.11 for the Au-Be/p-InSe:Cd SBDs. It has been determined a lateral homogeneous barrier height value of approximately 0.82 eV for these structures from the experimental linear relationship between barrier heights and ideality factors. The Schottky barrier height (SBH) value has been obtained from the reverse-bias C-V characteristics of Au-Be/p-InSe:Cd SBD for only one diode. At high currents in the forward direction, the series resistance effect has been observed. The value of series resistance has been determined from I-V measurements using Cheung’s and Norde’s methods.     

High voltage 4H-SiC Schottky barrier diodes

Characteristics of 4H-SiC Schottky barrier diodes with breakdown voltages up to 1000 V are reported for the first time. The diodes showed excellent forward I-V characteristics, with a forward voltage drop of 1.06 V at an on-state current density of 100 A/cm². The specific on-resistance for these diodes was found to be low (2×10 ^-3 Ω-cm² at room temperature) and showed a T ^1.6 variation with temperature. Titanium Schottky barrier height was determined to be 0.99 eV independent of the temperature. The breakdown voltage of the diodes was found to decrease with temperature     

Design considerations for planar Schottky barrier diodes

The cut-off frequency of the simplest planar Schottky diode on a uniformly doped n-layer of GaAs is derived. The theoretical results are given as functions of doping concentration and layer thickness with the specific contact resistance as parameter. An improved planar diode structure is presented with several short Schottky contact fingers connected in parallel. Experimental values ranging from 100 to 300 GHz agree with the calculated values when parasitic capacitances are taken into account.     

Current transport in large-area Schottky barrier diodes

The conventional method used to determine the mechanism of current transport in a Schottky barrier diode can lead to erroneous inferences if a fluctuation of parameters, such as that which would occur in a large area diode, is present. This has been illustrated by taking a Gaussian variation of a parameter in case of diodes showing T0anomaly.