In0.53Ga0.47AS/In0.52Al0.48As量子阱中的正磁电阻效应

在低温强磁场条件下,对In0.53 Ga0.47 As/In0.52AI0.48As量子阱中的二维电子气进行了磁输运测试.在低磁场范围内观察到正磁电阻效应,在高磁场下这一正磁电阻趋于饱和,分析表明这一现象与二维电子气中的电子占据两个子带有关.在考虑了两个子带之间的散射效应后,通过分析低磁场下的正磁电阻,得到了每个子带电子的迁移率,结果表明第二子带电子的迁移率高于第一子带电子的迁移率.进一步分析表明,这主要是由两个子带之间的散射引起的.     

The electronic structure of modulation-doped In0.53Ga0.47As/n-In0.52Al0.48As heterostructure

Summary The subband structure of modulation-doped InGaAs/InAlAs heterostructures is calculated in a variational self-consistent manner. The dependence on various device parameters is examined. The many-body exchange correlation effects are taken into account.     

Nonparabolic tendency of electron effective mass estimated by confined states in In0.53Ga0.47As/In0.52Al0.48As multi-quantum-well structures

We observed that a series of peaks, which were clearly extracted from a photocurrent difference spectrum, corresponded to interband optical transitions of an In_0.53Ga_0.47As /In_0.52Al_0.48As multi-quantum wells structure. The nonparabolic tendency of the electron effective mass was suggested from eigenenergies of conduction subbands. The effective mass estimated in a direction normal to the InGaAs quantum well plane was heavier than the effective mass of the bulk band edge and was 0.07 m₀at the top of a quantum potential well.     

In0.53 Ga0.47As/In0.52Al0.48As量子阱中双子带占据的二维电子气的输运特性

研究了不同沟道厚度的In0.53 Ga0.47As/In0.52Al0.48As量子阱中双子带占据的二维电子气的输运特性.在考虑了两个子带电子之间的磁致子带间散射效应后,通过分析Shubnikov-de Haas振荡一阶微分的快速傅里叶变换结果,获得了每个子带电子的浓度、输运散射时间、量子散射时间以及子带之间的散射时间.结果表明,对于所研究的样品,第一子带电子受到的小角散射更强,这与第一子带电子受到了更强的电离杂质散射有关.     

两个子带占据的In0.53Ga0.47As/In0.52Al0.48As量子阱中填充因子的变化规律

研究了低温(1.5K)和强磁场(0-13T)条件下,InP基In0.53Ga0.47As/In0.52Al0.48As量子阱中电子占据两个子带时填充因子随磁场的变化规律.结果表明,在电子自旋分裂能远小于朗道能级展宽的情况下,如果两个子带分裂能是朗道分裂能的整数倍时,即⊿E21=κ*ωc(其中κ为整数),填充因子为偶数;当两个子带分裂能为朗道分裂能的半奇数倍时,即⊿E21=(2κ 1*ω/2,填充因子出现奇数.     

Observation of confined states in anIn0.53Ga0.47As/In0.52Al0.48Asmulti-quantum wells structure by quantum confined Stark effects

Photocurrent spectra in an In_0.53Ga_0.47As /In_0.52Al_0.48As multi-quantum wells structure containing 9.4 nm wide wells were measured at room temperature in electric fields. The exciton peaks of ground-state transitions shifted fairly in 167 kV cm ^− 1as the quantum confined Stark effect. Stark shifts were calculated by using the Runge–Kutta method using the effective mass equation with our experimental band parameters. Our parameters are the hole effective masses and valence band offset derived from saturation of a highest eigen energy, electron effective mass depending on energies and the conduction band offset derived from observed quantum number. It was possible to sufficiently use our experimental band parameters for the calculation of the Stark shift in the electric field.     

Magnetotransport in modulation-doped In0.53Ga0.47As/In0.52Al0.48As heterojunctions: in-plane effective mass,quantum and transport mobilities of 2D electrons

Shubnikov–de Haas (SdH) and Hall effect measurements, performed in the temperature range between 3.3 and 20 K and at magnetic fields up to 2.3 T, have been used to investigate the electronic transport properties of lattice-matched In_0.53Ga_0.47As/In_0.52Al_0.48As heterojunctions. The spacer layer thickness (t_S) in modulation-doped samples was in the range between 0 and 400 Å. SdH oscillations indicate that two subbands are already occupied for all samples except for that witht_S =  400 Å. The carrier density in each subband, Fermi energy and subband separation have been determined from the periods of the SdH oscillations. The in-plane effective mass (m ^* ) and the quantum lifetime (τ_q) of 2D electrons in each subband have been obtained from the temperature and magnetic field dependences of the amplitude of SdH oscillations, respectively. The 2D carrier density (N₁) in the first subband decreases rapidly with increasing spacer thickness, while that (N₂) in the second subband, which is much smaller thanN₁ , decreases slightly with increasing spacer thickness from 0 to 200 Å. The in-plane effective mass of 2D electrons is similar to that of electrons in bulk In_0.53Ga_0.47As and show no dependence on spacer thickness. The quantum mobility of 2D electrons is essentially independent of the thickness of the spacer layer in the range between 0 and 200 Å. It is, however, markedly higher for the samples with a 400 Å thick spacer layer. The quantum mobility of 2D electrons is substantially smaller than the transport mobility which is obtained from the Hall effect measurements at low magnetic fields. The transport mobility of 2D electrons in the first subband is substantially higher than that of electrons in the second subband for all samples with double subband occupancy. The results obtained for transport-to-quantum lifetime ratios suggest that the scattering of electrons in the first subband is, on average, forward displaced in momentum space, while the electrons in the second subband undergo mainly large-angle scattering.     

Intraband Dynamics and Terahertz Emission in Biased GaAs/In0.53Ga0.47As Semiconductor Superlattices

Using an excitonic basis, we investigate the intraband polarization, optical absorption spectra, and terahertz emission of semiconductor superlattice with the density matrix theory. The excitonic Bloch oscillation is driven by the dc and ac electric fields. The slow variation in the intraband polarization depends on the ac electric field frequency. The intraband polarization increases when the ac electric field frequency is below the Bloch frequency. When the ac electric field frequency is above the Bloch frequency, the intraband polarization downwards and its intensity decreases. The satellite structures in the optical absorption spectra are presented. Due to excitonic dynamic localization, the emission lines of terahertz shift in different ac electric field and dc electric field.     

Intraband Dynamics and Terahertz Emission in Biased GaAs/In0.53Ga0.47As Semiconductor Superlattices

Using an excitonic basis, we investigate the intraband polarization, opticalabsorption spectra, and terahertz emission of semiconductor superlattice withthe density matrix theory. The excitonic Bloch oscillation is driven by the dcand ac electric fields. The slow variation in the intraband polarizationdepends on the ac electric field frequency. The intraband polarizationincreases when the ac electric field frequency is below the Bloch frequency.When the ac electric field frequency is above the Bloch frequency, theintraband polarization downwards and its intensity decreases. The satellitestructures in the optical absorption spectra are presented. Due to excitonicdynamic localization, the emission lines of terahertz shift in different acelectric field and dc electric field.     

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     

Modulated cyclotron resonance in multi-quantum well structure of In0.53Ga0.47As/InP induced by interband and exciton excitation

We report for the first time the modulated cyclotron resonance of electrons in the lattice-matched multi-quantum well structures of In_0.53Ga_0.47As/InP induced by monochromatic light beam of excitation. The resonant enhancement and modulation of the cyclotron resonance of electron due to interband and exciton excitation in the structures have been observed experimentally, which shows the possible prospect of the method for the observation of cyclotron resonances in semiconductors.October 26, 1993     

Theory of electronic and optical properties for different shapes of InAs/In0.52Al0.48As quantum wires

In this work, we propose an efficient method to investigate optical properties as well as their dependence on geometrical parameters in InAs/InAlAs quantum wires. The used method is based on the coordinate transformation and the finite difference method. It provides sufficient accuracy, stability and flexibility with respect to the size and shape of the quantum wire. The electron and hole energy levels as well as their corresponding wave functions are investigated for different shape of quantum wires. The optical transition energies, the emission wavelengths and the oscillator strengths are also studied.     

双δ掺杂In0.65Ga0.35As/In0.52Al0.48As赝型高迁移率晶体管材料子带电子特性研究

研究了基于InP基的In0.65Ga0.35As/In0.52Al0.48As赝型高迁移率晶体管材料中纵向磁电阻的Shubnikov-deHaas(SdH)振荡效应和霍耳效应,通过对纵向磁电阻SdH振荡的快速傅里叶变换分析,获得了各子带电子的浓度,并因此求得了各子带能级相对于费米能级的位置.联立求解Schrdinger方程和Poisson方程,自洽计算了样品的导带形状、载流子浓度分布以及各子带能级和费米能级位置.理论计算和实验结果很好符合.实验和理论计算均表明,势垒层的掺杂电子几乎全部转移到了量子阱中,转移率在95%以上.     

Temperature dependence of relaxation times in electron focusing and antidot structures made from In0.53Ga0.47As/InP heterojunctions

The magnetoresistance of antidot lattices and the magnetic field dependence of the three-terminal resistance of transverse electron focusing (TEF) devices is studied in a 2DEG in the lattice-matched In_0.53Ga_0.47As/InP heterojunction system, as a function of temperature. Ballistic effects are observed in both types of mesoscopic devices at temperatures exceeding 100 K, and are considerably more robust than Shubnikov–de Haas (SdH) oscillations. Two effects influence the decay in the amplitude of the magnetoresistance peaks in the antidot structures, and of the focusing peaks in the TEF devices: the thermal smearing of the Fermi surface, and the increase in the electron scattering time with increasing temperature due to the increase in electron–phonon scattering. We deduce the temperature dependencies of the scattering times for the different geometries.Copright 1998 Academic Press