Study of rectifying property of ITO/PI/TIPS-pentacene/Au diodes by electric field induced optical second harmonic generation

By using time-resolved electric field induced optical second harmonic generation (TR-EFISHG) measurement, we studied the rectifying property of organic double-layer diodes with a structure of indium-tin-oxide/polyimide/6,13-Bis(triisopropylsilylethynyl)-pentacene/gold (ITO/PI/TIPS-pentacene/Au). Upon application of a step voltage to the diodes, the TR-EFISHG probed the electric field changes induced in the TIPS-pentacene layer by hole injection from the ITO electrode, followed by the hole accumulation at the PI/TIPS-pentacene interface. Consequently, the electric field distributions in the diodes before and after the carrier injection were traced with accumulated charges at the PI/TIPS-pentacene interface, depending on the DC biasing applied to the diodes. Analyzing the carrier behavior in ITO/PI/TIPS-pentacene/Au on the basis of a Maxwell–Wagner model, we discussed the rectifying property of the diodes in terms of DC biasing effect, i.e., threshold-voltage shift, and concluded that space charge limited current process that flows across the PI layer governs the rectification of the diodes. Using the TR-EFISHG measurement is an effective way to study the rectifying property of organic double-layer diodes.     

High-temperature characteristics of AixGa1-xN/GaN Schottky diodes

High-temperature characteristics of the metal/AlxGa1_xN/GaN M/S/S (M/S/S) diodes have been studied with current-voltage (I-V) and capacitance-voltage (C-V) measurements at high temperatures. Due to the presence of the piezoelectric polarization field and a quantum well at the AIxGa1_xN/GaN interface, the AIxGa1_xN/GaNdiodes show properties distinctly different from those of the AIxGa1_xN diodes. For the AIxGa1_xN/GaN diodes, an increase in temperature accompanies an increase in barrier height and a decrease in ideality factor, while the AIxGa1_xN diodes are opposite. Furthermore, at room temperature, both reverse leakage current and reverse break-down voltage are superior for the AIxGa1_xN/GaN diodes to those for the AIxGa1_xN diodes.     

AlGaAs and GaAsP high-power ultrafast p+-n-n+diodes based on heterojunctions and a graded-gap base

The authors present a theoretical model of power p⁺-n-n ⁺ diodes with a graded-gap base and either homojunctions (GB) or heterojunctions (HGB), and numerical calculations of static and dynamic characteristics of AlGaAs (GaAsP) based structures. It is shown that HGB diodes will exhibit characteristics and properties significantly better than those of simple (homojunctions plus uniform base) GaAs and Si diodes. For example, the forward voltage drop in a high-voltage (W/L_p=13) high-frequency (t_rr=25 ns) HGB diode will be 50% and 300% smaller than the drop in, respectively, simple GaAs and Si diodes with the same W/L_p and t_rr. Other significant projected improvements include operation up to 450°C, an order of magnitude reduction in the reverse current, and a 50% increase in the breakdown voltage     

Optimization of MOVPE grownInxAl1-xAs/In0.53Ga0.47Asplanar heteroepitaxial Schottky diodes for terahertz applications

The feasibility of InP-based planar heteroepitaxial diodes for terahertz multiplier and mixer applications is explored. A variety of In _xAl_1-xAs/In_0.53Ga_0.47As (x=0.52, 0.4) diodes have been grown using LP-MOVPE and this allows systematic characterization of the effects of barrier thickness, InAs mole fraction and active layer thickness on the diode DC and RF performance. A new fabrication technology is developed for planar diodes using dielectric-free air-bridged anode fingers and trench isolation to minimize series resistance and parasitic capacitance. A qualitative model is suggested to explain the forward current conduction mechanism of the reported diodes. The control of forward current conduction and reverse leakage by epitaxial design together with the demonstrated figure-of-merit cutoff frequency of 2.6 THz make the diodes suitable for multiplier and mixer terahertz applications     

In1-xGaxAsyP1-y/InP DH lasers fabricated on InP

In1-xGaxAsyP1-y/InP double heterostructure (DH) laser diodes with emission wavelengths of1.25-1.35mum at room temperature were fabricated on     

Avalanche multiplication characteristics ofAl0.8Ga0.2As diodes

The avalanche multiplication characteristics of Al_0.8Ga _0.2As have been investigated in a series of p-i-n and n-i-p diodes with i-region widths, w, varying from 1 μm to 0.025 μm. The electron ionization coefficient, α, is found to be consistently higher than the hole ionization coefficient, β, over the entire range of electric fields investigated. By contrast with Al_xGa _1-xAs (x⩽0.6) a significant difference between the electron and hole initiated multiplication characteristics of very thin Al_0.8Ga_0.2As diodes (w=0.025 μm) was observed. Dead space effects in the diodes with w⩽0.1 μm were found to reduce the multiplication at low bias below the values predicted from bulk ionization coefficients. Effective α and β that are independent of w have been deduced from measurements and are able to reproduce accurately the multiplication characteristics of diodes with w⩾0.1 μm and breakdown voltages of all diodes with good accuracy. By performing a simple correction for the dead space, the multiplication characteristics of even thinner diodes were also predicted with reasonable accuracy     

氢对Al/p-Si Schottky二极管的影响(英文)

Al-contact Schottky diodes were made on p-type, B-doped Si in which hydrogen had been introduced in three different ways: growing in hydrogen, boiling in water and exposuring to the plasma-hydrogen. These Schottky diodes were characterized with C-V, I-V and DLTS measurements, showing that hydrogen injection results in (i)neutralization of acceptors; (ii)tncrease of the diffusion potential in the depletion region and decrease of the forward current; (iii) inhibition of deep level centers near the Al/Si interface.     

Efficient GaAs---Ga1−xAlxAs heterostructure electroluminescent diodes

The development of efficient GaAs(Zn) electroluminescent diodes using a GaAs---Ga_1−xAl_xAs single heterostructure design is reported. External equantum efficiencies (300°K) of 10 per cent have been achieved at 9100 Å (1.36 eV) with pulsed current densities at and above 70 A/cm² on square diodes embedded in epoxy domes. The heterostructure consists of a Ga_1−xAl_xAs (Zn) p-layer grown by liquid phase epitaxy on an n-type GaAs substrate with the simultaneous diffusion of Zn a distance of 2 μm into the substrate. Several features of the heterostructure design contribute to the high efficiency: (1) the 9100 Å emission suffers little absorption in the Ga_1−xAl_xAs, (2) there is little nonradiative recombination at the GaAs---Ga_1−xAl_xAs interface, and (3) the compensated p-region produces 9100 Å radiation whichi s not strongly absorbed in the n-GaAs regions of the device. The external quantum efficiencies obtained with the heterostructure devices are nearly an order of magnitude higher than those obtained from conventional Zn-diffused GaAs homostructure diodes with similar geometry. The solution growth, fabrication, and electroluminescence properties of the heterostructure diodes are described.     

Thermal effects on the forward characteristics of silicon p-i-n diodes at high pulse currents

When applying high pulse currents, the resulting temperature increase in the base regions of p-i-n diodes and thyristors leads to notable changes in the forward characteristics. (I) Decrease of carrier mobility noticeably increases the voltage drop across the diode and tends to limit the current density. (II) When the temperatures are sufficiently high to supply high intrinsic carrier concentrations, the temperature coefficient of the resistivity becomes negative. This can lead to current localization and destruction of the diodes.

To study these effects, the temperature of the base regions was monitored during high pulse currents using thermal i.r. emission. Indication for current limit occurs above 200°C, when the diodes are heated from room temperature. The negative temperature coefficient of the resistivity occurs at temperatures at which the intrinsic carrier concentration has reached the same order of magnitude as the injected carrier density. Simple theoretical treatment yields reasonably good agreement with the experimental results.     

Barrier height and ideality factor dependency on identically produced small Au/p-Si Schottky barrier diodes

Small high-quality Au/P-Si Schottky barrier diodes (SBDs) with an extremely low reverse leakage current using wet lithography were produced. Their effective barrier heights (BHs) and ideality factors from current-voltage (Ⅰ-Ⅴ) characteristics were measured by a conducting probe atomic force microscope (C-AFM). In spite of the identical preparation of the diodes there was a diode-to-diode variation in ideality factor and barrier height parameters. By ex-trapolating the plots the built in potential of the Au/p-Si contact was obtained as Vbi = 0.5425 V and the barrier height value φB(C-V) was calculated to be φB(C-V) = 0.7145 V for Au/p-Si. It is found that for the diodes with diameters smaller than 100 μm, the diode barrier height and ideality factor dependency to their diameters and correlation between the diode barrier height and its ideality factor are nonlinear, where similar to the earlier reported different metal semi-conductor diodes in the literature, these parameters for the here manufactured diodes with diameters more than 100μm are also linear. Based on the very obvious sub-nanometer C-AFM produced pictures the scientific evidence behind this controversy is also explained.     

Fabrication of high-performance AlxGa1-xAs/InyGa1-yAs/GaAs resonant tunneling diodes using amicrowave-compatible technology

A microwave-compatible process for fabricating planar integrated resonant tunneling diodes (RTDs) is described. High-performance RTDs have been fabricated using Al_xGa_1-xAs/In_y Ga_1-yAs/GaAs strained layers. Peak-to-valley current ratios (PVRs) of 4.8:1 with simultaneous peak current densities of 4×10⁴ A/cm² have been achieved at room temperature for diodes of area 9 μm². Accurate measurements of reflection gain versus frequency between 1.5 and 26.5 GHz in the negative differential region indicate that the present technology is promising for millimeter-wave integrated circuits including self-oscillating mixers, frequency multipliers, and detectors     

High-performance, metamorphic In/sub x/Ga/sub 1-x/As tunnel diodes grown by molecular beam epitaxy

Thin In/sub x/Ga/sub 1-x/As tunnel junction diodes having compositions from x=0.53 to 0.75 that span a range of bandgap energies from 0.74 to 0.55 eV, were grown on InP and metamorphic, step-graded In/sub x/Al/sub 1-x/As/InP substrates using molecular beam epitaxy and evaluated in the context of thermophotovoltaic (TPV) applications. Both carbon and beryllium were investigated as acceptor dopants. Metamorphic tunnel diodes with a bandgap of 0.60 eV (x=0.69) using carbon acceptor doping displayed highest peak current densities, in excess of 5900 A/cm/sup 2/ at a peak voltage of 0.31 V, within a 200 /spl Aring/ total thickness tunnel junction. Identically doped lattice-matched tunnel diodes with a bandgap of 0.74 eV exhibited lower peak current densities of approximately 2200 A/cm/sup 2/ at a higher peak voltage of 0.36 V, consistent with the theoretical bandgap dependence expected for ideal tunnel diodes. Specific resistivities of the 0.60 eV bandgap devices were in the mid-10/sup -5/ /spl Omega/-cm/sup 2/ range. Together with their 200 /spl Aring/ total thickness, the electrical results make these tunnel junctions promising for TPV applications where low-resistance, thin metamorphic tunnel junctions are desired.     

Characterization of light-emitting diodes based on InAsSbP/InAsSb structures grown by metal-organic vapor-phase epitaxy

Light-emitting diodes for the wavelength range λ=3.3–4.5 µm were fabricated on the basis of InAsSbP/InAsSb heterostructures grown by metal-organic vapor-phase epitaxy. The use of vapor-phase epitaxy made it possible to appreciably increase the phosphorus content in barrier layers (up to 50%) in comparison with that attainable in the case of liquid-phase epitaxy; correspondingly, it was possible to improve confinement of charge carriers in the active region of the structures. Photoluminescent properties of InAsSb layers, electroluminescent properties of light-emitting diodes, and dependences of the emission power on current were studied. Two types of light-emitting diodes were fabricated: (i) with extraction of emission through the substrate (type A) and (ii) with extraction of emission through the epitaxial layer (type B). The light-emitting diodes operating in the pulse mode (with a relative pulse duration of 20) had an emission power of 1.2 mW at room temperature.     

Small-frequency-difference stabilization of laser diodes using12C2H2 and 13C2H2 absorption lines for transmitter and local oscillator ofoptical heterodyne systems

Small-frequency-difference stabilization of distributed Bragg reflector (DBR) laser diodes has been demonstrated for the first time by using vibrational-rotational absorption of ¹²C₂H ₂ and ¹³C₂H₂ molecules. Frequency stabilization of two DBR laser diodes has been carried out at a wavelength of about 1.536 μm. The frequency difference between the two stabilized lasers was evaluated to be 9 GHz by the beat spectrum measurement. The experimental results suggest that such a pair of frequency-stabilized laser diodes with a small frequency difference could be used as the transmitter and local oscillator of optical heterodyne systems     

Characteristics of planar diodes based on heavily doped GaAs/AlAs superlattices in the terahertz frequency region

Characteristics of ohmic InGaAs contacts in planar diodes based on semiconductor superlattices with a small-area active region (1–10 μm²) are studied. The diodes were formed on the basis of short (18 or 30 periods) heavily doped (10¹⁸ cm⁻³) GaAs/AlAs superlattices with a miniband width of 24.4 meV. The reduced resistance of the ohmic contact was equal to 2×10⁻⁷ Ω cm² at room temperature. It is shown that the properties of fabricated planar diodes make it possible to use these diodes later on in semiconductor devices that operate in the terahertz frequency region in a wide temperature range (4–300 K). __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 9, 2004, pp. 1141–1146. Original Russian Text Copyright ? 2004 by Pavel’ev, Demarina, Koshurinov, Vasil’ev, Semenova, Zhukov, Ustinov.     

The power density giving rise to optical degradation of mirrors in InGaAs/AlGaAs/GaAs-based laser diodes

The InGaAs/AlGaAs/GaAs double laser heterostructures of separate confinement with a quantum well were formed by molecular-beam epitaxy. The study of characteristics of laser diodes with a wide contact (100 μm) showed that the power corresponding to the catastrophic degradation of mirrors may attain nearly the highest values ever achieved (20 MW/cm²) that were previously obtained for laser diodes based on InGaAsP/GaAs heterostructures alone. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 34, No. 11, 2000, pp. 1394–1395. Original Russian Text Copyright ? 2000 by Kotel’nikov, Katsnel’son, Kudryashov, Rastegaeva, Richter, Evtikhiev, Tarasov, Alferov.     

Silicon carbide pinch rectifiers using a dual-metal Ti-Ni/sub 2/Si Schottky barrier

The electrical characterization of dual-metal-planar Schottky diodes on silicon carbide is reported. The devices were fabricated on both 6H- and 4H-SiC by using titanium (Ti) and nickel silicide (Ni/sub 2/Si) as Schottky metals. These rectifiers yielded the same forward voltage drop as the Ti diodes and leakage current densities comparable to those of the Ni/sub 2/Si diodes. The reduction of the reverse leakage current density, with respect to that of the Ti diodes, was about three orders of magnitude in 6H and about a factor of 30 in 4H-SiC. All that results in a consistent reduction of the device power dissipation. Electrical characterization of the devices at different temperatures provided insight into the carrier transport mechanism. In particular, the electrical behavior of the system was explained by an "inhomogeneous" Schottky barrier model, in which the low Ti barrier determines the current flow under forward bias, whereas the high Ni/sub 2/Si barrier dominates the reverse bias conduction by the pinchoff of the low barrier Ti regions.     

Dependently addressable dual-spot native-oxide-confined GaInP-(AlxGa1-x)0.5In0.5Pquantum-well lasers

We describe the fabrication and characteristics of 15-μm spaced dual-spot, 670-nm native-oxide confined GaInP-(Al_xGa_1-x )_0.5In_0.5P quantum-well ridge waveguide laser diodes. The devices are fabricated from a compressively strained GaInP-(Al_xGa_1-x)_0.5In_0.5P quantum-well separate confinement heterostructure laser structure. Wet oxidation of Al_0.5In_0.5P is used to form native-oxide-confined dual-ridge waveguides. The oxidation process converts part of the p-Al_0.5In_0.5P cladding layer into AlO_x after ridge etching. These diodes show excellent performance: uniform low threshold currents of 15 mA and differential quantum efficiencies over 35%/facet. The diodes show crosstalk less than 2%     

Effect of Deep Centers on Charge-Carrier Confinement in InGaN/GaN Quantum Wells and on LED Efficiency

Semiconductors - The deep-center-assisted tunneling of carriers in p–n structures of light-emitting diodes (LEDs) with InGaN/GaN quantum wells (QWs) makes smaller the effective height of the...     

Characteristics of native-oxide-confined InGaP-(AlxGa1-x)0.5In0.5P quantum-well ridgewaveguide lasers

We report 670-nm native-oxide confined GaInP-(Al_xGa_1-x)_0.5In_0.5P quantum-well ridge waveguide laser diodes. The devices are fabricated from a compressively strained GaInP-(Al_xGa_1-x)_0.5In_0.5P quantum-well separate confinement heterostructure laser structure. Wet chemical etching and wet oxidation process are used to form native oxide confined ridge waveguides. The oxidation process converts the p-Al_0.5In_0.5P cladding layer into AlO_x after ridge etch. Laser diodes of 3.5-μm-wide ridge waveguide operate with threshold currents below 13.5 mA and differential quantum efficiencies over 35%/facet