大功率低功耗快速软恢复SiGeC功率开关二极管

为满足电力电子电路对功率开关二极管高频化的发展要求，提出了一种大功率低功耗快速软恢复p⁺(SiGeC)-n^--n⁺异质结二极管.与常规的Si p-i-n二极管相比，在正向电流密度不超过1000 A/cm²情况下，p⁺(SiGeC)-n^--n⁺二极管的正向压降减少了约1/5，有效降低了器件的通态功耗；反向恢复时间缩短了一半多，反向峰值电流降低了约25%，软 关键词： 快速软恢复 大功率低功耗 SiGeC/Si异质结功率二极管     

Optimization of optical characteristics of In0.29Ga0.71As0.99N0.01/GaAs straddled nano-heterostructure

Designing of a nanoscale Quantum Well (QW) heterostructure with a well thickness of ～60?Å is critical for many applications and remains a challenge. This paper has a detailed study directed towards designing of In_0.29Ga_0.71As_0.99N_0.01/GaAs straddled nanoscale-heterostructure having a single QW of thickness ～60?Å and optimization of optical and lasing characteristics such as optical and mode gain, differential gain, gain compression, anti-guiding factor, transparency wavelength, relaxation oscillation frequency (ROF), optical power and their mutual variation behavior. The outcomes of the simulation study imply that for the carrier concentration of ～2?×?10¹⁸cm^?3 the optical gain of the nano-heterostructure is of 2100?cm^?1 at the wavelength is of 1.30?μm. Though the obtained gain is almost half of the gain of InGaAlAs/InP heterostructure, but from the wavelength point of view the InGaAsN/GaAs nano-heterostructure is also more desirable because the 1.30?μm wavelength is attractive due to negligible dispersion in the silica based optical fiber. Hence, the InGaAsN/GaAs nano-heterostructure can be very valuable in optical fiber based communication systems.     

High frequency characterisation of double drift region InP and GaAs diodes

Computer studies have been made on the high frequency characteristics of symmetrically doped flat profile double drift region (DDR) InP and GaAs impatts in the mm-wave (60–100 GHz) frequency band. The spatial distribution of high frequency negative resistance and reactance in the depletion layer of DDR devices and their admittance properties have been investigated. The results indicate that DDR InP impatts should have higher drift zone voltage drop, higher negative resistance and higher negative conductance compared to their GaAs counterparts designed for the same range of mm-wave frequencies. Furthermore, the negative resistance peak is larger in magnitude for InP impatts compared to that for GaAs impatts. It is thus observed that DDR InP impatts should be superior to their GaAs counterparts as regards mm-wave power generation with high conversion efficiency.     

硼注入砷化镓的电子阻止本领

由文献上R_p的实验数据,用相对校正法和我们编制的LSS方程数值求解程序,算得B⁺→GaAs的电子阻止本领为NS_e(E)=12.4E^0.605,以及B⁺→GaAs的射程统计参数R_p,△R_p和R⊥。 关键词：     

EPR measurements on chromium doped GaAs,GaP and InP

EPR measurements have been made on chromium doped GaAs samples at 4.2 K. An n-type sample doped with chromium and silicon was irradiated with 2 MeV electrons to lower the Fermi level. No resonance from substitutional Cr⁺ (3d⁵) was detected, although the Cr_s²⁺ spectrum was observed. The generally accepted assignment of a spectrum to Cr_s⁺ for photoexcited samples must therefore be revised. An isotropic resonance with g = 2 is observed in p-type chromium doped GaAs, GaP and InP but it is still not clear whether this is due to Cr_s⁴⁺ or interstitial Cr_i⁺ (3d⁵).     

Dopant diffusion and segregation in semiconductor heterostructures: Part III, diffusion of Si into GaAs

We have mentioned previously that in the third part of the present series of papers, a variety of n-doping associated phenomena will be treated. Instead, we have decided that this paper, in which the subject treated is diffusion of Si into GaAs, shall be the third paper of the series. This choice is arrived at because this subject is a most relevent heterostructure problem, and also because of space and timing considerations. The main n-type dopant Si in GaAs is amphoteric which may be incorporated as shallow donor species Si_Ga ⁺ and as shallow acceptor species Si_As ^-. The solubility of Si_As ^- is much lower than that of Si_Ga ⁺ except at very high Si concentration levels. Hence, a severe electrical self-compensation occurs at very high Si concentrations. In this study we have modeled the Si distribution process in GaAs by assuming that the diffusing species is Si_Ga ⁺ which will convert into Si_As ^- in accordance with their solubilities and that the point defect species governing the diffusion of Si_Ga ⁺ are triply-negatively-charged Ga vacancies V_Ga ^3-. The outstanding features of the Si indiffusion profiles near the Si/GaAs interface have been quantitatively explained for the first time. Deposited on the GaAs crystal surface, the Si source material is a polycrystalline Si layer which may be undoped or n⁺-doped using As or P. Without the use of an As vapor phase in the ambient, the As- and P-doped source materials effectively render the GaAs crystals into an As-rich composition, which leads to a much more efficient Si indiffusion process than for the case of using undoped source materials which maintains the GaAs crystals in a relatively As-poor condition. The source material and the GaAs crystal together form a heterostructure with its junction influencing the electron distribution in the region, which, in turn, affects the Si indiffusion process prominently. Received: 19 April 1999 / Accepted: 3 May 1999 / Published online: 4 August 1999     

无定形靶中离子注入的R,Rp,△Rp的理论计算

本文在Thomas-Fermi势能基础上,导出了全射程R的解析解:R=2/a[E^1/2-A₁(arctg(2E^1/2-f)/△^1/2+arctg f/△^1/2)+B₁ln((E^1/2-f)²)/(E-fE^1/2+d) ·d/f²],其中A₁,B₁,f,d和△均为与离子及靶的质量、原子序数有关的常数。结合导出的η=R/(R_p)(R_p指投影射程)比值的双曲线函数关系 η=F(μ)[A₂(μ)+(B₂(μ))/(ε^1/2+C)],和ω=R_p/△R_p(△R_p指投影射程的标准偏差)比值的线性关系ω=A₃(μ)ε^1/21/2+B₃(μ),可简便而又准确地计算R,△R_p,R_p.这里F(μ),A₂(μ),B₂(μ), B₃(μ)和A₃(μ)为μ的代数函数,μ为离子与靶的质量比,C是经验常数.并对η等关系式的物理意义作了讨论。上述公式的计算结果与Gibbons的数值解结果及有关实验结果作了比较,表明可用于元素半导体如Si、二元化合物如GaAs以及三元化合物如SiO₂等;既对较轻离子适用,也对重离子适用,具有一定的普适范围。     

Noise characteristics of a superlattice avalanche photodiode

The noise generated due to randomness of multiplication process in the avalanche region of an Al _x Ga_1–x As/GaAs quantum well p⁺-i-n⁺ structure has been studied. The paper presents a quantitative evaluation of the noise performance of the superlattice APD which has not been done so far. Further, useful design data for low noise structure is given.     

Studies on the prospects of GaInAs and GaInAsP for double-drift region heterostructure IMPATTs

Double heterojunctions having the material combinations InP/GaInAs/InP, GaAs/GaInAs/GaAs and InP/GaInAsP/InP have been studied to assess their potential for double-drift region (DDR) IMPATT diodes. An accurate and realistic computer simulation program has been framed and used for the dc and high-frequency analysis of the DDRs. The analysis is carried out both in IMPATT (IMPact Avalanche Transit Time) and MITATT (MIxed Tunnelling Avalanche Transit Time) modes. Our results indicate that the GaAs/GaInAs/GaAs DDR would provide the best mm-wave performance up to sufficiently high frequencies. Further, the performance of the DDR diodes is observed to deteriorate at high frequency of operation due to phase distortion introduced by tunnel injected current, which is found to be the least in the case of GaAs/GaInAs/GaAs DDR leading to the best performance of this DDR amongst the three.     

磷化铟中离子注入硅的双性行为研究

本文研究了热靶条件下注Si⁺的磷化铟材料的电学特性和低温光致荧光特性,发现Si⁺单注入样品的薄层载流子浓度随注入剂量的增加而趋于饱和,共P⁺注入后薄层载流子浓度大大增加,低温光致荧光谱研究表明,注Si⁺的磷化铟中存在Si_p-V_p络合物缺陷,共P⁺注入能抑制其形成,表明Si⁺注入磷化铟中呈双性行为,还对Si⁺+P 关键词：     

Formation of the buffer layer of silicon suboxides SiOx in the Si/SiO2 low-dimensional heterosystem after Si+ ion implantation: Si L2, 3 X-ray emission spectra

Nanosized heterostructures n-Si/SiO₂ with different thicknesses of the oxide film (20, 500 nm) after implantation by Si⁺ ions with energies of 12 and 150 keV have been investigated using Si L _{2, 3} X-ray emission spectroscopy (the Si 3d3s → Si 2p _{1/2, 3/2} electronic transition). The ion-beam modification of the interface has been revealed and studied for the heterostructure with a silicon dioxide thickness of 20 nm. An analysis of the Si L _{2, 3} X-ray emission spectra has demonstrated that the Si⁺ ion implantation leads to the self-ordering of the structure of the initially amorphous SiO₂ film 20 nm thick due to the effect of high doses. A mechanism of ion-beam modification of the insulator-semiconductor interface has been proposed. No substantial transformation of the atomic and electronic structures of the heterostructure with a silicon dioxide thickness of 500 nm has been revealed after the ion implantation.     

Device linearity improvement and current enhancement utilizing high-to-low doping-channel FETs

We report device linearity improvement and current enhancement in both a heterostructure FET (HFET) and a camel-gate FET (CAMFET) using InGaAs/GaAs high-low and GaAs high-medium-low doped channels, respectively. In an HFET, a low doped GaAs layer was employed to build an excellent Schottky contact. In a GaAs CAMFET, a low doped layer together withn⁺andp⁺layers formed a high-performance majority camel-diode gate. Both exhibit high effective potential barriers of >1.0 V and gate-to-drain breakdown voltages of >20.0 V (atI_g=1.0 mA mm⁻¹). A thin, high doped channel was used to enhance current drivability and to improve the transconductance linearity. A 2×100 μm²HFET had a peak transconductance of 230 mS mm⁻¹and a current density greater than 800 mA mm⁻¹. The device had a transconductance of more than 80 percent of the peak value over a wide drain current range of 200 to 800 mA mm⁻¹. A 1.5×100 μm²CAMFET had a peak transconductance of 220 mS mm⁻¹and a current density greater than 800 mA mm⁻¹. Similarly, the device had a transconductance of more than 80 percent of the peak value over a wide drain current range of 160 to 800 mA mm⁻¹. The improvement of device linearity and the enhancement of current density suggest that high-to-low doped-channel devices for both an HFET and a CAMFET are suitable for high-power large signal circuit applications.     

SEM and XPS studies of nanohole arrays on InP(1 0 0) surfaces created by coupling AAO templates and low energy Ar ion sputtering

The aim of the present study is to demonstrate the feasibility to form well-ordered nanoholes on InP(1 0 0) surfaces by low Ar⁺ ion sputtering process in UHV conditions from anodized aluminum oxide (AAO) templates. This process is a promising approach in creating ordered arrays of surface nanostructures with controllable size and morphology. To follow the Ar⁺ ion sputtering effects on the AAO/InP surfaces, X-ray photoelectron spectroscopy (XPS) was used to determine the different surface species. In_4d and P_2p core level spectra were recorded on different InP(1 0 0) surfaces after ions bombardment. XPS results showed the presence of metallic indium on both smooth InP(1 0 0) and AAO/InP(1 0 0) surfaces. Finally, we showed that this experiment led to the formation of metallic In dropplets about 10 nm in diameter on nanoholes patterned InP surface while the as-received InP(1 0 0) surface generated metallic In about 60 nm in diameter.     

Enhancement of DD-reaction yields from the Ti/TiO2:Dx heterostructure by H+ and N+ ion beams using the GELIS setup

The results on DD-reaction yield enhancement from the Ti/TiO₂:D_x heterostructure by H⁺ and N⁺ ion beams in the energy range of 10–25 keV are presented. Neutron and proton fluxes weremeasured using a neutron detector based onHe-3 counters and a CR-39 plastic track detector. Measurements showed significant DD-reaction yield enhancement effects. The screening potential for this heterostructure under these experimental conditions was determined as U _e = 796 eV.     

Tunneling resonances in structures with a two-step barrier

Electron transport through an asymmetric heterostructure with a two-step barrier N⁺GaAs/N⁻GaAs/Al_0.4Ga_0.6As/Al_0.03Ga_0.97As/N⁻GaAs/N⁺GaAs was investigated. Features due to resonance tunneling both through a size-quantization level in a triangular quantum well, induced by an external electric field in the region of the bottom step of the barrier (Al_0.03Ga_0.97As layer), and through virtual levels in two quantum pseudowells of different width are observed in the tunneling current. The virtual levels form above the bottom step or above one of the spacers (N⁻GaAs layer) as a result of interference of electrons, in the first case on account of reflection from the Al_0.4Ga_0.6As barrier and a potential jump at the Al_0.03Ga_0.97As/N⁻GaAs interface and in the second case — from the Al_0.4Ga_0.6As barrier and the potential gradient at the N⁻GaAs/N⁺GaAs junction, reflection from which is likewise coherent. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 10, 814–819 (25 May 1998)     

Global predictions of T2 symmetric deep level wavefunctions in semiconductors

Numerical results of T₂ symmetric SP₃ bonded deep level wavefunctions due to short range defect potentials in Si, Ge, GaAs and InP are presented. The general features of defect wavefunctions are insensitive to either the band structure of the host of defect energy level. The total occupation probability of wavefunction located on 0 . 1 . 2 shells around the defect center is about 60–85%. This part of wavefunction may be expressed in several simple symmetric combinations of SP³ hybrid orbitals. The rest part of the wavefunction extends diversely over a wide range of space.     

正偏离Bragg定律的二元化合物靶中离子射程参数研究

研究了正偏离Bragg定律,即计算S_e(E)值高于实测S_e(E)的二元系化合物靶的离子射程特性。文中应用“regular”观点引入了“双原子模型”,在二元化合物靶的射程计算中,不仅考虑相同“原子对”对离子的阻止本领S₁₁(E),S₂₂(E),而且考虑不同“原子对”对离子的阻止本领S₁₂(E),S₂₁(E)。文中还应用Berthelot关系,使S₁₂(E)=S₂₁(E)=(S₁₁(E)·S₂₂(E))^1/2,则二元系靶的阻止本领及总的射程为NS(E)=1/2[(N₁S₁₁(E))^1/2+(N₂S₂₂(E)^1/2)]², R=4/a[x-A₁(arctg(2x+f)/△^1/2-arctg(f/△^1/2))-B₁(ln(x+g)²/g²·e/(x²+fx+e)) -b/2 ln(x²+fx+e/e)。这里X=E^1/2,E为离子注入能量,所有其它常数是与离子和靶的质量、原子序数有关的常数。结合文献[1]提出的R与R_p,R_p与△R_p的关系式,可计算得正偏离系统的投影射程R_p及其偏差量△R_p。并对各关系式的物理意义作了阐明。 关键词：     

Thermal expansion coefficient of GaAs and InP

The temperature dependence of the thermal expansion for GaAs and InP is investigated theoretically using the experimental pressure derivatives of elastic stiffness constants and phonon frequencies. The linear correlation between the transverse acoustical mode Grüneisen parameter γ^X_TA and the metallic transion pressure P_t obtained by Weinstein is not satisfied for GaAs and InP, but the observed thermal expansion of GaAs is well reproduced. In addition, the linear expansion coefficient of InP is predicted theoretically as a function of temperature. Then, the phonon dispersion curves of GaAs and InP at their covalent-metallic transition pressures are quantitatively shown.     

Optically induced gate voltage spectroscopy in a GaAs/AlGaAs heterostructure

We report on measurements of optically induced gate voltage spectroscopy in a GaAs/AlGaAs heterostructure with a high mobility 2-dimensional electron gas (2DEG) in a thin (55 nm) GaAs layer. The optically induced gate voltage between the front gate and the 2DEG is sensitive to excess electron concentrations below 10⁷ cm⁻². In the gate voltage spectrum we observe a peak below the bandgap energy of GaAs, which is not observed in the photocurrent, luminescence or excitation spectra. Due to the extremely high sensitivity of this technique we attribute this below bandgap signal to very weak absorption lines below the GaAs bandgap energy by impurity bands or defect absorption. The fall-off of the below bandgap signal varies as exp (hω/E₀), where E₀ is an indicative for the quality of the heterostructure.     

Studies on the high-frequency properties of 〈111〉, 〈110〉 and 〈100〉 oriented GaAs IMPATT diodes

High-frequency analysis has been carried out to predict the rf performance of 111, 110 and 100 oriented p ⁺ nn ⁺, n ⁺ pp ⁺ (single drift region) and n ⁺ npp ⁺ (double drift region) GaAs IMPATT diodes for opertion at 35 and 60 GHz. The microwave performance is observed to be highly sensitive to crystal orientation in case of p ⁺ nn ⁺ and n ⁺ npp ⁺ diodes whereas orientation of the substrate has negligible effect on n ⁺ pp ⁺ avalanche diodes. The calculation shows that 111 oriented GaAs IMPATT diode would provide the largest magnitude of negative resistance and negative conductance for both SDR p ⁺ nn ⁺ and DDR n ⁺ npp ⁺ diodes which indicates that high microwave power with high conversion efficiency can be realised from these 111 oriented GaAs devices. This result can be explained from the experimental data of electron and hole ionization rates for different orientations in GaAs.