Manganese-related luminescence in GaInAs/AlInAs multiple quantum wells grown on InP by molecular beam epitaxy

Two Mn-related luminescence peaks have been observed in a series of nominally undoped Ga_0.47In_0.53As/Al_0.48In_0.52As multiple quantum wells (MQW) grown lattice-matched on InP substrates by molecular beam epitaxy. These two peaks correspond to on-center and on-edge impurity states, respectively. The origin of the Mn impurities is outdiffusion from the Fe-doped semiinsulating InP substrate into the epitaxial layer. The binding energy of Mn acceptors, determined to be 53±3 meV in bulk-like Ga_0.47In_0.53As, increases to 80±5 meV for the on-center Mn state in a 58 Å MQW. The strong well-width dependence of the binding energy is explained in terms of the unique behavior of the Mn impurity in III–V semiconductors. The Mn in Ga_0.47In_0.53As and Ga_0.47In_0.53As/Al_0.48In_0.52As MQWs behaves predominantly as a deep impurity.On leave from: A. F. Ioffe Physicotechnical Institute, Leningrad, USSR     

Dependence of current-voltage characteristics of pseudomorphic AlAs/In0.53a0.47s/InAs resonant tunneling diodes on quantum well widths

This paper studies the dependence of I-V characteristics on quantum well widths in AlAs/In_0.53Ga_0.47As and AlAs/In_0.53Ga_0.47As/InAs resonant tunneling structures grown on InP substrates. It shows that the peak and the valley current density in the negative differential resistance region are closely related with quantum well width. The measured peak current density, valley current densities and peak-to-valley current ratio of resonant tunneling diodes are continually decreasing with increasing well width.     

Experimental confirmation by galvanomagnetic methods of a complex transport model in In0.53Ga0.47As layers deposited by MBE on SI-InP

At low temperatures In_0.53Ga_0.47As samples show an increase of carrier concentration, which can be explained in terms of a two carriers transport model. This type of problem exists since the beginning of the semiconductor era, dating back to monocrystalline germanium.We propose that in all the investigated layers, there are X atoms or charged dislocations in the region of the first monolayers, which are built in during epitaxial growth. The layers were intentionally undoped. They form an impurity band in which low mobility carriers dominate over the localised electron scattering due to the s-d exchange interaction. These carriers do not freeze out at liquid helium temperature and give rise to two transport media for electrons; a conduction band at higher temperatures and an impurity band at lower temperatures. The electron which fall down onto the previously ionised X atoms, then move by thermally activated hopping. We show that the two carriers model for In_0.53Ga_0.47As epitaxial layers are confirmed by the carrier concentration-temperature, carrier concentration-magnetic field, resistivity-magnetic field behaviour, and also by YKA theory also. The differences between the two transport models are so distinctive that observed phenomena may exist. This paper presents experimental results, which constitute comprehensive evidence for the complicated structure of the semiconductor epitaxial layers on the sample of n-type In_0.53Ga_0.47As/InP layer with n=2.2×10¹⁵/cm³.     

Particular nanowire superlattice as a spin filter

A nanowire superlattice of InAs and GaAs layers with In_0.47Ga_0.53As as the impure layers is proposed. The oft-neglected k³ Dresselhaus spin-orbit coupling causes the spin polarization of the electron but often can produce a limited spin polarization. In this nanowire superlattice, Dresselhaus term produce complete spin filtering by optimizing the distance between the In_0.47Ga_0.53As layers and the Indium (In) in the impure layers. The proposed structure is an optimized nanowire superlattice that can efficiently filter any component of electron spins according to its energy. In fact, this nanowire superlattice is an energy dependent spin filter structure.     

Ion-irradiated In0.53Ga0.47As photoconductive antennas for THz generation and detection at 1.55 μm wavelength

We present a detailed study of the photoconductive antennas made from heavy-ion-irradiated In_0.53Ga_0.47As material. The optical and transport properties of ion-irradiated In_0.53Ga_0.47As material are characterized. The terahertz waveforms emitted and detected by ion-irradiated In_0.53Ga_0.47As photoconductive antennas excited by 1.55 μm wavelength femtosecond laser pulses are reported and the effect of the carrier lifetime on the terahertz signal characteristics emitted by such devices is analysed. The performances of ion-irradiated In_0.53Ga_0.47As photoconductive antennas excited by 1.55 μm and also by 0.8 μm wavelength femtosecond laser pulses are compared to those of similar low-temperature-grown GaAs photoconductive antennas. To cite this article: J. Mangeney, P. Crozat, C. R. Physique 9 (2008).     

Type-I and type-II Wannier-Stark effect in InGaAs/InGaAs superlattices

The formation of minibands is demonstrated in photocurrent experiments on shallow In_0.53Ga_0.47As/In_0.40Ga_0.60 As superlattices grown by low-pressure metal-organic vapor-phase epitaxy. Field-dependent variations of the spectral shape are attributed to Wanner-Stark localization. Both type-I transitions between electrons and heavy holes and type-II transitions involving light holes confined in the In_0.40Ga_0.60 As layers are observed and distinguished by their characteristic field dependence.     

Study of single event effect for the InP-based HEMT with In0.53Ga0.47As/In0.3Ga0.7As/In0.7Ga0.3As composite channel

In this study, the single event effects in In_0.53Ga_0.47As/In_0.3Ga_0.7As/In_0.7Ga_0.3As composite channel InP-based HEMT are investigated using TCAD simulation for the first time. Due to the higher conduction band difference between bottom In_0.7Ga_0.3As channel and InAlAs buffer, the electrons in the buffer layer induced by ions strike cannot enter the channel, led to reduce the peak concentration in the composite channel and significantly weakened the drain current for composite channel device. Meanwhile, higher barrier height under the gate for composite channel InP-based HEMT is formed after particle strike, and further attenuate the drain current. Therefore, the single event effects can be effectively reduced by designing channel structure. In addition, drain voltage and incident position also show significant impact drain current. With the increase in the drain voltage, the drain current increase and the most sensitive incident position is the gate electrode for the device.     

Structural and electronic properties of group III Rich In0.53Ga0.47As(001)

The structural and electronic properties of group III rich In_0.53Ga_0.47As(001) have been studied using scanning tunneling microscopy/spectroscopy (STM/STS). At room temperature (300 K), STM images show that the In_0.53Ga_0.47As(001)–(4 × 2) reconstruction is comprised of undimerized In/Ga atoms in the top layer. Quantitative comparison of the In_0.53Ga_0.47As(001)–(4 × 2) and InAs(001)–(4 × 2) shows the reconstructions are almost identical, but In_0.53Ga_0.47As(001)–(4 × 2) has at least a 4× higher surface defect density even on the best samples. At low temperature (77 K), STM images show that the most probable In_0.53Ga_0.47As(001) reconstruction is comprised of one In/Ga dimer and two undimerized In/Ga atoms in the top layer in a double (4 × 2) unit cell. Density functional theory (DFT) simulations at elevated temperature are consistent with the experimentally observed 300 K structure being a thermal superposition of three structures. DFT molecular dynamics (MD) show the row dimer formation and breaking is facilitated by the very large motions of tricoodinated row edge As atoms and z motion of In/Ga row atoms induced changes in As–In/Ga–As bond angles at elevated temperature. STS results show there is a surface dipole or the pinning states near the valence band (VB) for 300 K In_0.53Ga_0.47As(001)–(4 × 2) surface consistent with DFT calculations. DFT calculations of the band-decomposed charge density indicate that the strained unbuckled trough dimers being responsible for the surface pinning.     

InP-based InGaAs/InAlGaAs digital alloy quantum well laser structure at 2 μm

The structural and optical characteristics of InP-based compressively strained InGaAs quantum wells have been significantly improved by using gas source molecular beam epitaxy grown InAs/In 0.53 Ga 0.47 As digital alloy triangular well layers and tensile In 0.53 Ga 0.47 As/InAlGaAs digital alloy barrier layers.The x-ray diffraction and transmission electron microscope characterisations indicate that the digital alloy structures present favourable lattice quality.Photoluminescence (PL) and electroluminescence (EL) measurements show that the use of digital alloy barriers offers better optical characteristics than that of conventional random alloy barriers.A significantly improved PL signal of around 2.1 μm at 300 K and an EL signal of around 1.95 μm at 100 K have been obtained.     

Numerical study of strained InGaAs quantum well lasers emitting at 2.33 μm using the eight-band model

We investigate the band structure of a compressively strained In(Ga)As/In 0.53 Ga 0.47 As quantum well (QW) on an InP substrate using the eight-band k · p theory.Aiming at the emission wavelength around 2.33 μm,we discuss the influences of temperature,strain and well width on the band structure and on the emission wavelength of the QW.The wavelength increases with the increase of temperature,strain and well width.Furthermore,we design an InAs /In 0.53 Ga 0.47 As QW with a well width of 4.1 nm emitting at 2.33 μm by optimizing the strain and the well width.     

Time-resolved,hot-electron conductivity measurement using an electro-optic sampling technique

A picosecond electro-optical sampling technique has, for the first time, been used for measuring the high-electrical-field instabilities in a semiconductor. Current-voltage-characteristics and the high-field domain nucleation time for n-type In_0.53 Ga_0.47 As samples have been measured with a time resolution better than 10 ps and compared with existing theoretical calculations.     

Engineering of AlON interlayer in Al2O3/AlON/In0.53Ga0.47As gate stacks by thermal atomic layer deposition

The presence of an AlN interfacial layer in high-k/In_0.53Ga_0.47As gate stacks improves the interfacial properties and enhances the electrical performance of devices. However, pure AlN is rarely grown by atomic layer deposition (ALD) because of the low reactivity of NH₃ toward the common Al-precursor and the predisposition to oxidation of the grown AlN layer. Although a plasma-enhanced ALD technique significantly suppresses the oxygen content in the grown AlN layer, the deterioration of the interface properties by plasma-damage is a critical issue. In this work, an AlON interlayer was engineered by optimizing the NH₃ feeding time in thermal ALD to improve the interface quality in Al₂O₃/AlON/In_0.53Ga_0.47As capacitors. It was determined that a mere increase in the NH₃ feeding time during the ALD of the AlON film resulted in a higher nitrogen incorporation into the AlON interlayer, leading to a reduction in the interface trap density. Furthermore, the out-diffusion of elements from the In_0.53Ga_0.47As layer was effectively suppressed by increasing the NH₃ feeding time. This work demonstrates that simple process optimization can improve the interface quality in high-k/In_0.53Ga_0.47As gate stacks without the use of any plasma-activated nitrogen source.     

Electromodulation spectroscopy of In0.53Ga0.47As/In0.53Ga0.23Al0.24As quantum wells

In_0.53Ga_0.47As/In_0.53Ga_0.23Al_0.24As quantum wells (QWs) of various widths have been grown by molecular beam epitaxy on the InP substrate and investigated by electromodulation spectroscopy, i.e. photoreflectance (PR) and contactless electroreflectance (CER). The optical transitions related to the QW barrier and the QW ground and excited states have been clearly observed in PR and CER spectra. The experimental QW transition energies have been compared with theoretical predictions based on an effective mass formalism model. A good agreement between experimental data and theoretical calculations has been observed when the conduction band offset for the In_0.53Ga_0.47As/In_0.53Ga_0.23Al_0.24As interface equals 60%. In addition, it has been concluded that the conduction band offset for the In_0.53Ga_0.23Al_0.24As/InP interface is close to zero. The obtained results show that InGa(Al)As alloys are very promising materials in the band gap engineering for structures grown on InP substrate.     

Analysis and evaluation of uniformity of SWIR InGaAs FPA—Part I: Material issues

The nonuniformity caused by fluctuations of indium composition, thickness and doping concentration of epitaxial absorption layer of InGaAs focal plane arrays (FPAs) is estimated theoretically with the incorporation of practical status. By the measurements on epitaxy wafers of 2 in. size, the fluctuation of indium composition is observed to be less than ±0.2% and ±1% for lattice matched In_0.53Ga_0.47As and wavelength extended In_0.80Ga_0.20As photodetector structures respectively, while the thickness and doping fluctuations are assumed to be the same. Results show that the response nonuniformity caused by fluctuation of indium composition is dependent on the target wavelength and can be neglected with a minor composition fluctuation if the cutoff wavelength is well set. The total response nonuniformity induced by the effects of thickness and doping fluctuations, which dominates the FPA performance for large signal applications, is estimated to be less than ±0.1% and ±0.5% for In_0.53Ga_0.47As and In_0.80Ga_0.20As FPAs smaller than 1 in. in maximum side length. Neglecting the effects of defects, the total detectivity nonuniformity caused by these fluctuations is about ±2% for In_0.53Ga_0.47As FPA and will reach up to about ±19% for In_0.80Ga_0.20As FPA, where the dark current nonuniformity due to the fluctuation of composition plays the most critical role.     

Improvement of photoluminescence and electroluminescence characteristics of MBE-grown In0.53Ga0.47As/In0.53(Ga0.6Al0.4)0.47As quantum well laser structure with InGaAlAs digital alloys by thermal annealing

We investigated the effect of rapid thermal annealing (RTA) on the photoluminescence (PL) and electroluminescence of the In_0.53Ga_0.47As/In_0.53(Ga_0.6Al_0.4)_0.47As multiple quantum well (MQW) laser structure with InGaAlAs barrier layers provided by the digital-alloy technique. The SiO₂- (Si₃N₄-) capped samples followed by the RTA exhibited a significant improvement of PL intensity without any appreciable shifts in PL peak energy for settings of up to 750 °C (800 °C) for 45 s. This improvement is attributed to the annealing of nonradiative defects in InAlAs layers of digital-alloy InGaAlAs and partially those near the heterointerfaces of the digital-alloy layers. The InGaAs/InGaAlAs MQW laser diodes fabricated on the samples annealed at 850 °C show a hugely improved lasing performance. Received: 2 September 2002 / Accepted: 3 September 2002 / Published online: 17 December 2002 RID="*" ID="*"Corresponding author. Fax: +82-62/970-2204, E-mail: ytlee@kjist.ac.kr     

XPS data for sputter-cleaned In0.53Ga0.47As,GaAs, and InAs surfaces

Core level binding energies and Auger parameters were determined for In, Ga, and As in the three compounds In_0.53Ga_0.47As, GaAs, and InAs. The surfaces were cleaned by 1.5 keV Ar ion bombardment. Under this condition the radiation-induced defects are small. In the case of GaAs the Ga and As3d levels become comparable with available data for chemically cleaned surfaces. The high Ga deficiency of chemically cleaned In_0.53Ga_0.47As surfaces could not be observed. Sputter cleaned surfaces seem to be closer to the bulk composition.     

低温InGaAs/InAlAs多量子阱的分子束外延生长与表征

采用气源分子束外延(GSMBE)生长了低温InGaAs材料,研究了生长温度及As压对InGaAs材料性质的影响,得到优化的生长条件为:生长温度为300 ℃、As压为77.3 kPa。通过Be掺杂,并采用In0.52Al0.48As/In0.53Ga0.47As多量子阱结构,将材料的方块电阻提高到1.632106 /Sq,载流子数密度降低至1.0581014 cm-3。X射线衍射结果表明:InGaAs多量子阱材料具有较高的晶体质量。这种Be掺杂InGaAs多量子阱材料缺陷密度大且电阻率高,是制作太赫兹光电导天线较理想的基质材料。收稿日期:; 修订日期:     

Spectrum analysis of interband optical transmissions and quantitative model of eigen-energies and absorptions in In0.53Ga0.47As/In0.52Al0.48As multi-quantum well structures

Interband transmission spectra were measured for three In_0.53Ga_0.47As/In_0.52Al_10.48As multi-quantum well specimens having different carrier concentrations by modulation-doping. Spectral shapes of transmissions were clear steplike structures but exciton peaks of first order transitions were masked with the carrier concentrations. The spectral shapes changed hardly between 100 and 310 K. Using our parameters of quantum wells, calculated eigen-energies for three specimens agreed with experiments and absorption coefficients reproduced experimental transmission spectra at any temperature.     

赝形InxGa1-xAs/In0.52Al0.48As异质结构中二维电子气的回旋共振光谱研究

采用回旋共振光谱方法，同时获得了具有较高电子气浓度的赝形In_0.80Ga_0.20As/In_0.53Ga_0.47As/In_0.52Al_0.48AsHEMT结构中最低两个子能带的费密面附近电子有效质量、 散射时间和迁移率.观察到该系统中能带非抛物性和波函数穿透所导致的电子回旋有效质量的显著增大效应，以及合金无序势和电离杂质散射所引起的电子散射时间和迁移率明显的子带依赖性. 关键词：     

Optical studies of In0.53Ga0.47As

We present luminescence data obtained as a function of temperature and excitation in In_0.53Ga_0.47As and In_0.7Ga_0.3As_0.63P_0.37. We assign the different lines and correlate the luminescence results with transmission measurements.