高p型掺杂对高亮度发光二极管的作用

根据统计学理论系统分析了p掺杂在高亮度发光二极管中(HB-LED)的作用,研究了p型限制层掺杂浓度及浓度梯度变化时导带势垒的变化,由此得到对提高电子有效约束的浓度范围;提高电流扩展层的掺杂浓度,减小电阻率,使得注入器件的电流得到充分的扩展.两者是提高器件的外量子效率非常有效的方法.实验证明了理论分析是正确的.     

A CMOS-compatible rapid vapor-phase doping process for CMOS scaling

An advanced CMOS process, which used rapid vapor-phase doping (RVD) for pMOSFETs and solid-phase diffusion (SPD) for nMOSFETs, has been developed. Using the RVD technique, a 40-nm-deep p-type extension with a sheet resistance as low as 400 /spl Omega//sq has been realized. These RVD and SPD devices demonstrate excellent short-channel characteristics down to 0.1 /spl mu/m channel length and 40% higher drain current, compared with conventional devices with ion implanted source/drain (S/D) extensions, and high-speed circuit performance. We investigate the effect of the S/D extension structure on the device performance and find that a gate extension overlap of 25 nm enables excellent dc and high-speed circuit performance in 0.1-/spl mu/m devices.     

Highly efficient silicon light emitting diodes produced by doping engineering

This paper reviews our recent progress on silicon (Si) pn junction light emitting diodes with locally doping engineered carrier potentials.Boron implanted Si diodes with dislocation loops have electrol...     

GaN n- and p-type Schottky diodes: Effect of dry etch damage

The reverse breakdown voltage (V_B) and forward turn-on voltage (V_F) of n- and p-GaN Schottky diodes were used to examine the effects of Cl₂/Ar and Ar plasma damage. Even short plasma exposures (4 secs) produced large changes in both V_B and V_F, with ion mass being a critical factor in determining the magnitude of the changes. The damage depth was established to be 500-600 Å and the damaged material could be removed in boiling NaOH solutions, producing a full recovery of the diode properties. Annealing at 700 to 800°C under N₂ produced only a partial recovery of V_B and V_F     

Characteristics of 6H-silicon carbide PIN diodes prototyping by laser doping

Silicon carbide PIN diodes have been fabricated using a direct-write laser-doping technique that reduces defect generation compared to the conventional ion-implantation technique. Nitrogen and aluminum were successfully incorporated into SiC as n-type and p-type dopants, respectively. Rutherford backscattering studies were conducted to compare the lattice defect generation by the laser-doping and ion-implantation techniques. No amorphization was observed in laser-doped samples, eliminating the need for high-temperature annealing. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the PIN diodes were also investigated. The silicon carbide diodes are intended for high-temperature and high-voltage power electronics applications.     

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.     

High-performance millimetre-wave mixer diodes fabricated using a deep mesa etch approach

Schottky-barrier junction mixer diodes compatible with monolithic integration have been fabricated on semi-insulating GaAs substrates using buried VPE n+ layers and deep mesa etch processing. A 590 GHz cutoff frequency was determined using modified DeLoach analysis and fin-line chip mounting. A 5.3 dB (SSB) noise figure and a 4.8 dB conversion loss were obtained at 35 GHz for a pair of chips in a balanced microstrip mixer.     

Very-high-speed silicon bipolar transistors with in-situ dopedpolysilicon emitter and rapid vapor-phase doping base

We present a detailed study of the performance of very-high-speed silicon bipolar transistors with ultra-shallow junctions formed by thermal diffusion. Devices are fabricated with double-polysilicon self-aligned bipolar technology with U-groove isolation on directly bonded SOI wafers to reduce the parasitic capacitances. Very thin and low resistivity bases are obtained by rapid vapor-phase doping (RVD), which is a vapor diffusion technique using a source gas of B₂H₆. Very shallow emitters are formed by in-situ phosphorus doped polysilicon (IDP) emitter technology with rapid thermal annealing (RTA). In IDP emitter technology, the emitters are formed by diffusion from the in-situ phosphorus doped amorphous silicon layer. Fabricated transistors are found to have ideal I-V characteristics, large current gain and low emitter resistance for a small emitter. Furthermore, a minimum ECL gate delay time of 15 ps is achieved using these key techniques. Analyses of the high performance using circuit and device simulations indicate that the most effective delay components of an ECL gate are cut-off frequency and base resistance. A high cut-off frequency is achieved by reducing the base width and active collector region. In this study, RVD is used to achieve both high cut-off frequency and low base resistance at the same time     

Tunable microcavities in organic light-emitting diodes by way of low-refractive-index polymer doping

A method for enhancing the light out-coupling efficiency of organic light-emitting devices (OLEDs) has been demonstrated by blending a low-refractive-index polymer, poly(2,2,3,3,3-pentafluoropropyl methacrylate) (PPFPMA), into the emission layer. The resonant wavelength of the weak microcavity devices blueshifted accompanied with a decrease in refractive indices of the light-emitting layers after the addition of PPFPMA. Stronger directed emission toward the surface normal was obtained when the resonant wavelength became closer to the peak wavelength of intrinsic emission spectrum of the organic emitters. The luminous efficiency of the devices was enhanced by more than 20%. The results suggest that the microcavity properties of the OLEDs can be tunable through blending low-refractive-index materials.     

Mechanism of doping gallium arsenide with carbon tetrachloride during organometallic vapor-phase epitaxy

The rates of decomposition of carbon tetrachloride (CCl₄), triethylgallium (TEGa), and tertiarybutylarsine (TBAs), and the rate of GaAs film growth, were measured as a function of the process conditions during organometallic vapor phase epitaxy. In addition, the reaction of CCl₄ with the GaAs(001) surface was monitored in ultrahigh vacuum using infrared spectroscopy, temperature-programmed desorption, and scanning tunneling microscopy. These experiments have revealed that CCl₄ adsorbs onto Ga sites, and decomposes by transferring chlorine ligands to other Ga atoms on the surface. Chlorine and gallium desorb from the surface as GaCl, while the carbon incorporates into the lattice. Triethylgallium is consumed by two competing reactions: GaAs film growth and GaCl etching. Depending on the V/III and IV/III ratios and temperature, the etch rate can be high enough to prevent any GaAs deposition.     

Efficiency versus doping profile in GaAs read-type IMPATT diodes

The influence of doping profile on the efficiency of GaAs Read-type IMPATT diodes has been studied experimentally. A diode with low breakdown voltage, or a diode with a low bias field in the drift region, gave the highest efficiency. The mechanism will be discussed, estimating the restriction of RF voltage amplitude and the change of phase relation between RF current and voltage.     

Optimal doping of the drift region in unipolar diodes and transistors

An exact analytical solution to the problem of minimizing the drift-region resistance in high-power unipolar devices was obtained. It is shown that the optimal dopant profile N(x) features a minimum in the central part of the drift region and increases without restriction when either of the boundaries of this region are approached.     

Barrier height engineering on GaAs THz Schottky diodes by means ofhigh-low doping, InGaAs- and InGaP-layers

Barrier height engineering of n-GaAs-based millimeter-wave Schottky diodes using strained InGaAs/GaAs and InGaP/GaAs heterostructures and a high doping surface layer is presented. The Schottky barrier height can be varied between Φ_fb=0.52 eV and Φ_fb=1.0 eV. The use of a pseudomorphic InGaAs layer and/or a thin high doping layer at the surface significantly reduces the Schottky barrier height. This is advantageous for low-drive zero bias mixing applications, A full quantum mechanical numerical calculation is presented to simulate the influence of different high doping layer thicknesses on the diode's dc characteristic. The theoretical results are compared with experimental results, For reverse bias applications (e.g., varactors) a barrier height and breakdown voltage enhancement is realized with a lattice matched InGaP/GaAs heterostructure. The barrier height value is determined by temperature dependent dc-measurements. The epitaxial layered structures are grown by molecular beam epitaxy. The diode devices are fabricated in a fully planar technology using selective oxygen implantation for lateral isolation. The diode's cut-off frequencies are in the THz-range     

Study of the characteristics of ultraviolet light-emitting diodes based on GaN/AlGaN heterostructures grown by chloride-hydride vapor-phase epitaxy

The results of work on developing and studying ultraviolet (UV) light-emitting diodes (LEDs) based on GaN/AlGaN heterostructures fabricated on Al₂O₃(0001) substrates by the chloride-hydride vaporphase epitaxy are presented. The maximum in the electroluminescence spectrum is located in the wavelength range of 360–365 nm, and its full width at half maximum is 10–13 nm. At a working current of 20 mA, the optical density and efficiency of the UV LED are 1.14 mW and 1.46%, respectively.     

Preparation of ZnSe light-emitting diodes by metalorganic chemical vapor deposition using trisdimethylaminoarsine as a p-type doping source

Trisdimethylaminoarsine was used in atmospheric-pressure metalorganic chemical vapor deposition growth of ZnSe on GaAs. The metalorganic precursors employed for ZnSe growth were diethylzinc and diethylselenide, and ethyliodide was used as then-type dopant. P-on-n light emitting diode (LED) structures were prepared, and molecular beam epitaxially deposited HgTe layers were used as ohmic contacts to the p-type ZnSe. Blue LEDs were fabricated on p-on-n samples. Preliminary LED data and the material characterization data are presented.     

Frequency control of self-sustained pulsating laser diodes byuniform impurity doping into multiple-quantum-well structures

The self-sustained pulsating frequency in index guided AlGaAs multiple-quantum-well (MQW) laser diodes is controlled by impurity doping into the active region to reduce the relative intensity noise induced by optical feedback through a short optical path. Uniform n-type impurity doping into an MQW structure more effectively reduces the frequency by decreasing the differential gain than does modulation doping with an n-type impurity. Uniform doping of 1×10¹⁸ cm^-3 into each quantum well layer reduces the frequency to less than 0.8 GHz, which corresponds to half or two-thirds that of undoped lasers. The uniformly n-doped self-sustained pulsating lasers provided low noise characteristics with a relative intensity noise below 1×10³ Hz^-1 under an optical feedback of 20% even with a short optical path length of 60 mm     

The doping effect of cesium-based compounds on carrier transport and operational stability in organic light-emitting diodes

The doping effect of cesium compounds (i.e., Cs₂CO₃, CsN₃ and CsF) doped electron injection layer (EIL) on charge transport properties and operational stability of organic light-emitting diodes (OLEDs) was systematically investigated in this work. It has been found that device characteristics and lifetime are highly dependent on the doping constituent materials. The doping of cesium compounds in EIL can improve the charge injection and transport of OLEDs, due to the increase in conductivity and reduction in electron injection barrier. Apart from the difference in electrical characteristics, the operational stability of OLEDs is strongly influenced by the doping mechanism of different cesium compounds in the EILs. The OLED device using Cs₂CO₃ as the n-type dopant for the EIL shows a superiority in both electrical property and operational lifetime.     

掺杂浓度和无序对柔性有机发光二极管载流子迁移率的影响

基于电荷分布的泊松方程和载流子输运方程,考虑最低能量非占据态和最高能量占据态的载流子态密度服从双高斯分布的模型,自洽地研究了掺杂浓度和无序对Alq3柔性有机发光二极管载流子迁移率的影响.发现掺杂浓度低于1×1020cm-3时,掺杂浓度对迁移率影响很小,迁移率几乎保持不变;当掺杂浓度大于1×1020cm-3时,载流子迁移率非线性增加,与实验结果很好一致.考虑不同无序度时,发现无序度的增加,相应的迁移率下降;低掺杂浓度下迁移率与无序度的大小关系不大,当掺杂浓度较高的时,无序度较小的材料迁移率增加较快.最终给出了柔性发光二极管器件的发光功率密度与电压关系,表明载流子浓度和无序相关的迁移率结果对制备高性能的柔性有机发光二极管具有指导意义.     

DFB LD manufactured by nanoimprint lithography

Gratings of distributed feedback laser diodes (DFB LDs) have been successfully manufactured by nanoimprint lithography (NIL). Uniform gratings with periods of about 240 nm and phase-shifted in the center have been fabricated by a soft press NIL employing a polymer stamp technology. Moreover, the shape of the grating is rectangle, rather than sinusoidal by holography.The test results show good characteristics of the electrical and spectral output. The results of this study indicate that NIL has high potential for the manufacture of DFB LDs.