1.3 µm vertical microcavities with InAs/InGaAs quantum dots and devices based on them

Various structures with optical microcavities and active layers based on InGaAs/GaAs quantum dots MBE-grown on GaAs substrates were studied theoretically and experimentally. LEDs for the 1.3 μm spectral range with narrow spectral characteristics and low light beam divergence were fabricated. Vertical lasing at 1.3 μm was obtained in a structure with oxidized AlO/GaAs mirrors under injection pumping. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 7, 2001, pp. 889–895. Original Russian Text Copyright ? 2001 by Sakharov, Krestnikov, Maleev, Kovsh, Zhukov, Tsatsul’nikov, Ustinov, Ledentsov, Bimberg, Lott, Alferov.     

InGaAs/InP heterostructures with strained quantum wells and quantum dots (λ=1.5–1.9 µm)

Strongly strained In_xGa_1−x As/In_0.53Ga_0.47As/InP heterostructures with indium content x=0.69−1.0 in the active region were investigated experimentally and theoretically. Two types of structures were obtained by vapor-phase epitaxy from metalorganic compounds: 1) with isolated compression-strained quantum wells and 2) with self-organized nanosize InAs clusters (quantum dots). The temperature dependence of the quantum radiation efficiency of samples with quantum wells in the temperature range 77–265 K is characterized by T ₀=43 K. One reason for the low value of T ₀ is electron delocalization in the active region. The maximum radiation wavelength obtained in structures with quantum dots is 1.9 μm at 77 K. Fiz. Tekh. Poluprovodn. 33, 1105–1107 (September 1999)     

Transport properties of InGaAs/GaAs Heterostructures with δ-doped quantum wells

The lateral transport of electrons in single- and double-well pseudomorphic GaAs/n-InGaAs/GaAs heterostructures with quantum wells 50–100 meV deep and impurity δ-layers in the wells, with concentrations in the range 10¹¹ < N _s < 10¹² cm⁻², has been investigated. Single-well structures with a doped well at the center exhibit a nonmonotonic temperature dependence of the Hall coefficient and an increase in low-temperature electron mobility with an increase in the impurity concentration. The results obtained indicate that the impurity-band electron states play an important role in the conductivity of these structures. Involvement of the impurity band also allows to explain adequately the characteristics of the conductivity of double-well structures; in contrast to single-well structures, band bending caused by asymmetric doping is of great importance. The numerical calculations of conductivity within the model under consideration confirm these suggestions.     

Optical properties of metamorphic GaAs/InAlGaAs/InGaAs heterostructures with InAs/InGaAs quantum wells,emitting light in the 1250–1400-nm spectral range

It is demonstrated that metamorphic GaAs/InAlGaAs/InGaAs heterostructures with InAs/InGaAs quantum wells, which emit light in the 1250–1400 nm spectral range, can be fabricated by molecular-beam epitaxy. The structural and optical properties of the heterostructures are studied by X-ray diffraction analysis, transmission electron microscopy, and the photoluminescence method. Comparative analysis of the integrated photoluminescence intensity of the heterostructures and a reference sample confirm the high efficiency of radiative recombination in the heterostructures. It is confirmed by transmission electron microscopy that dislocations do not penetrate into the active region of the metamorphic heterostructures, where the radiative recombination of carriers occurs.     

Comparison of different concepts of InAs quantum dot growth on GaAs for 1.3-μm-range lasers

The DWELL (dots-in-a-well), DUWELL (dots-under-the-well), and GC-SRL (gradient-composition-strain-reducing-layer) concepts of InAs quantum dot epitaxial growth under identical conditions have been compared. The laser structures are designed for operation near 1.3 ??m. An improved procedure is proposed for estimating the InAs growth rate. The dependence of the photoluminescence peak??s spectral position and intensity on the structure type and epitaxy conditions has been studied. A 10-stack DUWELL ridge waveguide laser diode with ground-state lasing at room temperature has been demonstrated.     

Arrays of 128×128 photodetectors based on HgCdTe layers and multilayer heterostructures with GaAs/AlGaAs quantum wells

A technology has been elaborated and photodetector modules based on Hg_1−x Cd_xTe/GaAs heterostructures and GaAs/AlGaAs multiquantum-well structures grown by molecular-beam epitaxy were fabricated for the 3–5 and 8–12 μm spectral ranges. The photosensitive HgCdTe layers were grown on the GaAs substrates with the intermediate buffer layer of CdZnTe. To decrease the surface effect on the recombination processes, the graded-gap Hg_1−x Cd_xTe layers with x increasing towards the surface were grown. A silicon multiplexer was designed and fabricated by CMOS/CCD technology with a frame rate of 50 Hz. The hybrid microassembly of the photodetector array and the multiplexer was produced by group cold welding on indium columns while monitoring the connection process. The fabricated 128×128 modules based on HgCdTe layers with the cutoff wavelengths 6 and 8.7 μm had a temperature resolution of 0.02 K and 0.032 K, respectively, at a temperature of 78 K and a frame rate of 50 Hz. The photosensitive GaAs/AlGaAs multilayer quantum well structures were fabricated by MBE. It is shown that the technology developed allows 128×128 multielement photodetector arrays (λ_peak=8 μm) to be produced with a temperature resolution of 0.021 K and 0.06 K at operating temperatures of 54 K and 65 K, respectively. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 9, 2001, pp. 1159–1166. Original Russian Text Copyright ? 2001 by Ovsyuk, Sidorov, Vasil’ev, Shashkin.     

Effect of thermal annealing on the photoluminescence of structures with InGaAs/GaAs quantum wells and a low-temperature GaAs layer δ-doped with Mn

The effects of isochronal thermal annealing (at 325–725°C) on the radiative properties of InGaAs/GaAs nanoheterostructures containing a low-temperature GaAs layer δ-doped with Mn grown by laser deposition are studied. A decrease in the photoluminescence intensity and increase in the ground transition energy are observed upon thermal impact for quantum wells located near the low-temperature GaAs layer. The distribution of Mn atoms in the initial and annealed structures is obtained by secondary-ion mass spectrometry. A qualitative model of the observed effects of thermal annealing on the radiative properties of the structures is discussed; this model takes into account two main processes: diffusion of point defects (primarily gallium vacancies) from the GaAs coating layer deep into the structure and Mn diffusion in both directions by the dissociation mechanism. Magnetization studies show that, as a result of thermal annealing, an increase in the proportion of the ferromagnetic phase at room temperature (presumably, MnAs clusters) in the low-temperature GaAs coating layer takes place.     

A spatially single-mode laser for a range of 1.25–1.28 μm on the basis of InAs quantum dots on a GaAs substrate

Spatially single-mode lasing in the wavelength range of 1.25–1.28 μm was accomplished in injection lasers on GaAs substrates. The peak output power is 110 mW at room temperature, and the differential quantum efficiency amounts to 37%. The active region of the laser is formed by an array of self-organizing InAs quantum dots. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 34, No. 1, 2000, pp. 117–120. Original Russian Text Copyright ? 2000 by Mikhrin, Zhukov, Kovsh, Maleev, Ustinov, Shernyakov, Kayander, Kondrat’eva, Livshits, Tarasov, Maksimov, Tsatsul’nikov, Ledentsov, Kop’ev, Bimberg, Alferov.     

Dilute nitrides and 1.3 μm GaInNAs quantum well lasers on GaAs

We present epitaxial growth of GaInNAs on GaAs by molecular beam epitaxy (MBE) using analog, digital and N irradiation methods. It is possible to realize GaInNAs quantum wells (QWs) with a maximum substitutional N concentration up to 6% and a strong light emission up to 1.71 μm at 300 K. High quality 1.3 μm GaInNAs multiple QW edge emitting laser diodes have been demonstrated. The threshold current density (for a cavity of 100×1000 μm²) is 300, 300, 400 and 940 A/cm² for single, double, triple and quadruple QW lasers, respectively. The maximum 3 dB bandwidth reaches 17 GHz and high-speed transmission at 10 Gb/s up to 110 °C under a constant voltage has been demonstrated.     

GaAsSb/GaAs strained structures with quantum wells for lasers with emission wavelength near 1.3 μm

Optimum conditions for the growth of the GaAs_{1 − x} Sb _x /GaAs heterostructures by the method of molecular-bean epitaxy are determined; it is shown that effective long-wavelength photoluminescence at T = 300 K can be obtained at wavelengths as long as λ = 1.3 μm by increasing the antimony incorporation. As the excitation power is increased, the appearance of a short-wavelength line (in addition to a shift of a photoluminescence maximum to shorter wavelengths characteristic of the type II heterojunctions) related to direct optical transitions in the real space takes place; this relation is confirmed by the results of studying the photoluminescence spectra with subpicosecond and nanosecond time resolution in the case of pulsed excitation.     

InGaAs/GaAs structures with quantum dots in vertical optical cavities for wavelengths near 1.3 µm

Semiconductor heterostructures with vertical optical cavities with active regions, based on arrays of InAs quantum dots inserted in an external InGaAs quantum well, have been obtained by molecular-beam epitaxy on GaAs substrates. The dependences of the reflection and photoluminescence spectra on the structural characteristics of the active region and optical cavities have been investigated. The proposed heterostructures are potentially suitable for optoelectronic devices at wavelengths near 1.3 μm. Fiz. Tekh. Poluprovodn. 33, 629–633 (May 1999)     

Optical properties of InGaAs/InGaAlAs quantum wells for the 1520–1580 nm spectral range

The optical properties of elastically strained semiconductor heterostructures with InGaAs/InGaAlAs quantum wells (QWs), intended for use in the formation of the active region of lasers emitting in the spectral range 1520–1580 nm, are studied. Active regions with varied lattice mismatch between the InGaAs QWs and the InP substrate are fabricated by molecular beam epitaxy. The maximum lattice mismatch for the InGaAs QWs is +2%. The optical properties of the elastically strained InGaAlAs/InGaAs/InP heterostructures are studied by the photoluminescence method in the temperature range from 20 to 140°C at various power densities of the excitation laser. Investigation of the optical properties of InGaAlAs/InGaAs/InP experimental samples confirms the feasibility of using the developed elastically strained heterostructures for the fabrication of active regions for laser diodes with high temperature stability.     

Laser (λ = 809 nm) power converter based on GaAs

Laser-power converters with a wavelength of λ = 809 nm are fabricated on the basis of single-junction AlGaAs/GaAs heterostructures grown by the method of liquid-phase epitaxy (LPE). Photovoltaic modules with an operating voltage of 4 V for converting radiation of various densities are developed and tested. Two approaches—without the use of optical concentrating systems and with the use of Fresnel lenses are investigated. A monochromatic conversion efficiency exceeding 44% is attained with a photovoltaic module based on 64 laser-radiation converters 0.04 cm² in area and a concentrating system made of a quartz-lens matrix.     

Influence of defect formation as a result of incorporation of a Mn δ layer on the photosensitiviy spectrum of InGaAs/GaAs quantum wells

The influence of defect formation upon the deposition of a Mn δ layer and a GaAs coating layer (with the use of laser evaporation) on the photosensitivity spectra of heterostructures with InGaAs/GaAs quantum wells located in the near-surface region has been studied.     

GaAs-based 1.3 µm InGaAs quantum dot lasers: A status report

We review the present status of InGaAs quantum dot lasers on GaAs sub-strates emitting near and at 1.3 μm. Such lasers are shown to be extremely promising for cost-efficient commercial applications in optical fiber communication. Threshold current densities a low as ∼20 Acm⁻² per QD sheet are achieved. Room temperature continuous wave operation at 2.7 W for broad stripe devices is demonstrated. The maximum differential efficiency amounts to 57%. Moreover, single lateral mode continuous wave operation with a maximum output power of 110 mW is realized. Prospects for 1.3 μm GaAs-based vertical cavity surface emitting lasers are given. We also show that the longest wavelength of QD GaAs-based light emitting devices can be potentially extended to 1.7 μm.     

III–V compound materials and lasers on silicon

Silicon-based photonic integration has attracted the interest of semiconductor scientists because it has high luminous efficiency and electron mobility. Breakthroughs have been made in silicon-based integrated lasers over the past few decades. Here we review three main methods of integration of III–V materials on Si, namely direct growth, bonding, and selective-area hetero-epitaxy. The III–V materials we introduced mainly include materials such as GaAs and InP. The lasers are mainly lasers of related communication bands. We also introduced the advantages and challenges of the three methods.     

Ⅲ–Ⅴ compound materials and lasers on silicon

Silicon-based photonic integration has attracted the interest of semiconductor scientists because it has high luminous efficiency and electron mobility.Breakthroughs have been made in silicon-based integrated lasers over the past few decades.Here we review three main methods of integration ofⅢ–Ⅴ materials on Si,namely direct growth,bonding,and selectivearea hetero-epitaxy.TheⅢ–Ⅴmaterials we introduced mainly include materials such as GaAs and InP.The lasers are mainly lasers of related communication bands.We also introduced the advantages and challenges of the three methods.     

Continuous-wave disk WGM lasers (λ = 3.0 μm) based on InAs/InAsSbP heterostructures

Semiconductors - IR semiconductor WGM lasers operating in the continuous-wave (CW) mode at a wavelength of 3.04 μm have been fabricated by metal-organic vapor-phase epitaxy on the basis of...     

1.3 μm GaAs-based quantum well and quantum dot lasers: Comparative analysis

New generation of long-wavelength (1.3 μm) GaAs based lasers is discussed. The modal gain, threshold current, quantum efficiency characteristics and temperature stability of lasers based on InGaAsn quantum wells and InAs/InGaAs quantum dots are compared.     

Impurity states in a spherical GaAs–Ga1-x AlxAs quantum dots: Effects of hydrostatic pressure

We calculated the binding energies of shallow donors and acceptors in a spherical GaAs–Ga${}_{1-x}$Al${}_x$As quantum dot under isotropic hydrostatic pressure for both a finite and an infinitely high barrier. We use a variational approach within the effective mass approximation. The binding energy is computed as a function of hydrostatic pressure, the dot sizes and the impurity position. The results show that the impurity binding energy increases with the pressure for any position of the impurity. We have also found that the binding energy depends on the location of the impurity and the pressure effects are less pronounced for impurities on the edge.