Showing papers on "Quantum well published in 1983"
TL;DR: In this paper, a single quantum well of GaAs has been observed, and the current singularity and negative resistance region are dramatically improved over previous results, and detecting and mixing have been carried out at frequencies as high as 2.5 THz.
Abstract: Resonant tunneling through a single quantum well of GaAs has been observed. The current singularity and negative resistance region are dramatically improved over previous results, and detecting and mixing have been carried out at frequencies as high as 2.5 THz. Resonant tunneling features are visible in the conductance‐voltage curve at room temperature and become quite pronounced in the I‐V curves at low temperature. The high‐frequency results, measured with far IR lasers, prove that the charge transport is faster than about 10−13 s. It may now be possible to construct practical nonlinear devices using quantum wells at millimeter and submillimeter wavelengths.
900 citations
TL;DR: In this paper, the ground state and four excited states of a hydrogenic impurity in quantum well structures are calculated using a variational approach using a single slab of GaAs sandwiched between two semi-infinite slabs of Ga1−xAlxAs.
239 citations
TL;DR: In this paper, the spontaneous lifetime of electrons and holes within the quantum well decreases with well thickness, from 1 ns for ε = 14$ nm to 350 ps for δ = 5$ nm, due to enhanced recombination due to localization of the carriers.
Abstract: Picosecond luminescence experiments on $\mathrm{GaAs}/{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ quantum well structures reveal a significant influence of localization on the transition probabilities of photoexcited carriers. The spontaneous lifetime of electrons and holes within the quantum well decreases with well thickness ${L}_{z}$ from 1 ns for ${L}_{z}=14$ nm to 350 ps for ${L}_{z}=5$ nm because of the enhanced recombination due to localization of the carriers.
182 citations
TL;DR: In this article, the binding energy of excitons in a semiconductor (e.g., GaAs) quantum well to each other and to neutral donors is calculated variationally using the six-parameter wave function of Brinkman, Rice and Bell.
Abstract: The binding energy of excitons in a semiconductor (e.g., GaAs) quantum well to each other and to neutral donors is calculated variationally using the six-parameter wave function of Brinkman, Rice, and Bell. The biexciton results for wells of various thicknesses agree closely with some of the data previously assigned to the biexciton. The biexciton binding relative to the exciton binding in the two-dimensional limit is about 3-4 times larger than in the three-dimensional case, but otherwise varies in a similar way with the mass ratio. It is found that the biexciton and bound exciton closely obey Haynes's rule.
173 citations
TL;DR: In this article, a simple model for the linewidth enhancement factor α and its frequency dependence in semiconductor lasers is presented, which is in reasonable agreement with the experimental results.
Abstract: A simple model for the linewidth enhancement factor α and its frequency dependence in semiconductor lasers is presented. Calculations based on this model are in reasonable agreement with experimental results.
155 citations
TL;DR: In this paper, a new type of infrared photodetector using free electron absorption in a heavily doped GaAs/GaAlAs quantum well structure has been demonstrated, and preliminary results indicate a strong response in the near infrared with a responsivity conservatively estimated at 200 A/W.
Abstract: A new type of infrared photodetector using free electron absorption in a heavily doped GaAs/GaAlAs quantum well structure has been demonstrated. Preliminary results indicate a strong response in the near infrared with a responsivity conservatively estimated at 200 A/W. The structure can potentially be tailored during fabrication for use in several infrared bands of interest, including the 3 to 5 micron band and the 8 to 10 micron band.
145 citations
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15 Aug 1983
TL;DR: In this article, a model for mass transport of two-dimensional surface profiles for which a Cartesian coordinate system can be conveniently used has been developed for the fabrication of microoptical structures.
Abstract: : A model has been developed for mass transport of two-dimensional surface profiles for which a Cartesian coordinate system can be conveniently used. Simple analytical solutions have been obtained that provide valuable insights for the fabrication of microoptical structures. A mode of laser operation has been discovered that allows a single Nd:YAG laser with an intracavity nonlinear crystal to stably generate light at the 589-nm sum frequency of the 1064- and 1320-nm outputs. The dynamics of this new mode of operation has been investigated experimentally. The frequency response of the microchip laser to pump-power modulation has been derived in closed form. It is shown that pump-power modulation is a viable technique to change the output frequency of microchip lasers. Strained InGaAs/A1GaAs quantum-well diode lasers have been fabricated on Si substrates for the first time, with the objective of improving laser reliability by incorporating in the active layer to inhibit the propagation of dark-line defects. One graded-index separate-confinement heterostructure single-quantum-well laser with an In0.05Ga0.95As active layer has operated CW for 56.5 h, a record lifetime for GaAs-based diode lasers on Si. Thin films of polysilyne have been patterned by exposure with 193-nm radiation followed by selective etching of the unexposed areas in a HBr plasma. Patterns with 0.2microns resolution and high aspect ratio were obtained when this dry development process was applied to bilayers consisting of polysilyne on an organic planarizing layer.
121 citations
TL;DR: In this paper, the cooling rate of the electron hole plasma in these two dimensional structures is approximately the same as for bulk GaAs at comparable photo-excitation density, and the authors investigated the dynamics of hot carrier relaxation, exciton screening and subband level renormalization in GaAs.
102 citations
TL;DR: In this article, the first observation of DFWM in room-temperature GaAs/GaAlAs multiple quantum well structures near the exciton resonances near the heavy hole was reported.
Abstract: We report the first observation of forward degenerate four‐wave mixing (DFWM) in room‐temperature GaAs/GaAlAs multiple quantum well structures near the exciton resonances. In a sample 1.26 μm thick with sixty‐five 96‐A GaAs quantum wells we observe ∼10−4 diffraction efficiency with ∼30 W/cm2 average intensity from a mode‐locked laser. We measure nonlinear absorption and DFWM spectra, and also a change in refractive index, per carrier pair/cm3, of neh∼2×10−19 cm3 just below the heavy hole exciton peak. With 20‐ns carrier lifetime this corresponds to an effective nonlinear coefficient for cw beams of ‖n2‖≂2×10−4 cm2/W. This is appreciably larger than previous estimates and encouraging for room‐temperature all‐optical devices.
94 citations
TL;DR: In this paper, the Wannier excitons in quantum wells for the ground and excited states were compared, with careful attention to a variety of spatial extensions of these excitions in directions parallel and perpendicular to the well interface.
Abstract: Variational calculations are presented for Wannier excitons in quantum wells for the ground ($1s$) and the excited ($2s$ and $2p$) states, with careful attention to a variety of spatial extensions of these excitons in directions parallel and perpendicular to the well interface. The results are shown to be valid throughout the entire well thickness, corresponding in the thin and the thick limits to two- and three-dimensional situations, respectively.
93 citations
TL;DR: In this paper, the authors discussed the possible intrinsic limitation on the temperature dependence of threshold current of long wavelength InGaAsP quantum well lasers caused by Auger recombination and intervalence band absorption.
Abstract: We discuss the possible intrinsic limitation on the temperature dependence of threshold current of long wavelength InGaAsP quantum well lasers caused by Auger recombination and intervalence band absorption. A model calculation of the various band‐to‐band Auger rates are presented. We find that the Auger rates increase with decreasing band gap and also with increasing temperature as in the case of bulk semiconductors. The temperature dependence and the band‐gap dependence arises from the energy and momentum conservation (in the direction normal to the well) that the four particle states involved must satisfy. The estimated Auger coefficient is large enough to be important in single quantum well lasers. However, the Auger effect should be much smaller in a multiquantum well laser than for a single quantum well laser. This is because the carrier density at threshold is smaller (by a factor of 3 to 4) for multiquantum well lasers than for single quantum well lasers. The increased intervalence band absorption ...
TL;DR: In this article, the conduction and the valence band edges of one semiconductor are shifted upward relative to those of the other to exhibit adjacent dual quantum wells for electrons and holes on the two sides of the interface.
Abstract: Heterojunctions in which both the conduction and the valence band edges of one semiconductor are shifted upward relative to those of the other, can exhibit adjacent dual quantum wells for electrons and holes on the two sides of the interface. Tunneling-assisted radiative recombination between the wells should be an efficient, bias-tunable source of radiation at below-gap quantum energies. Several semiconductor combinations that exhibit the proper lineup are available.
TL;DR: In this paper, the growth of multiquantum well and single quantum well Ga0.47In0.53As•InP structures by low pressure metalorganic chemical vapor deposition is described.
Abstract: We describe the growth of multiquantum well and single quantum well Ga0.47In0.53As‐InP structures by low pressure metalorganic chemical vapor deposition. The multiwell structure consists of 25‐, 50‐, 100‐, and 200‐A quantum wells (Ga0.47In0.53As layers) separated by 500‐A barriers (InP layers). Auger measurements indicate the presence of four distinct wells with abrupt boundaries. Photoluminescence measurements are consistent with the existence of four wells; however, deviations are noted between experimentally determined and theoretically predicted recombination energies. An analogous situation exists for the single (50 and 100 A) quantum well structures. Possible explanations, including variation of well composition, variation of well thickness, and participation of impurities in the recombination process are suggested.
TL;DR: In this paper, thermal annealing was used to modify the wavelength of a photopumped, low threshold AlxGa1−xAs quantum well heterostructure (QWH) laser from ∼8200 to ∼7300 A with a threshold change from 150 to 1700 W/cm2.
Abstract: Data are presented showing that thermal annealing (875–‐900 °C) can be used to modify the wavelength of a photopumped, low threshold AlxGa1−xAs quantum well heterostructure (QWH) laser from ∼8200 to ∼7300 A with a threshold change from 150 to 1700 W/cm2. The energy levels of the annealed single quantum well crystal are approximated by fitting a modified Poschl–Teller potential to the band‐edge profile as modified by layer (Al–Ga) interdiffusion. The layer (Al–Ga) interdiffusion coefficient (at 875 °C) is found to be smaller, by a factor of 3–4, than previously reported. We suggest that this is due to the high quality, i.e., low defect density, of the ultralow threshold QWH crystals of this work.
TL;DR: In this article, a continuous (cw) 300-k laser operation of a 66-period lower energy GaAs•InxGa1−xAs (x∼0.25) and a 128-period GaAs−InxPx•GaAs (∼ 0.2) superlattice (SL) was demonstrated.
Abstract: Continuous (cw) 300‐K laser operation of a 66‐period lower energy GaAs‐InxGa1−xAs (x∼0.2) strained superlattice (SL) and a higher energy 128‐period GaAs1−xPx‐GaAs (x∼0.25) strained SL is demonstrated. The strained SL’s are grown by organometallic vapor phase epitaxy (OMVPE) or metalorganic chemical vapor deposition (MOCVD) with higher gap quaternary confining layers and LB ∼75 A barriers and Lz ∼75 A quantum wells. These SL’s are unstable during high level excitation, failing in 2–20 min when operated cw at 300 K as photopumped lasers.
TL;DR: In this paper, the authors calculate the mobility of carriers in a quantum well structure when they are scattered by ionized impurities in the size-quantum limit (SQL) where the carriers are assumed to populate only the lowest quantized energy level.
Abstract: We calculate the mobility of carriers in a quantum well structure when they are scattered by ionized impurities in the size‐quantum limit (SQL) where the carriers are assumed to populate only the lowest quantized energy level. It is found that the probability of scattering due to ionized impurities decreases with the well thickness in contrast to the case of acoustic phonon scattering where the scattering probability is enhanced under the conditions of the SQL. The temperature and thickness dependence of the mobility depends critically on the screening of the Coulomb potential due to the presence of the ionized impurities.
TL;DR: In this article, a two-electron transition model was proposed for GaSb well structures with diameters less than 45 A. The authors showed that the photon energy with well width indicates strong nonparabolicity effects; it is in good agreement with Bastard's simple model of quantum wells in nonparabolous semiconductors.
Abstract: Multiquantum well structures of GaSb wells down to 12‐A width, separated by 120‐A AlSb barriers, were grown by molecular beam epitaxy, and their low‐temperature photoluminescence was studied. Even though GaSb should become an indirect‐gap semiconductor for well widths below about 90 A, the direct‐gap luminescence persists to the narrowest wells. The shift of photon energy with well width indicates strong nonparabolicity effects; it is in good agreement with Bastard’s simple model of quantum wells in nonparabolic semiconductors. For wells less than 45 A wide, the direct‐gap luminescence is accompanied by a strong and very broad lower‐energy luminescence peak, which appears to be related to electron accumulation in the X valleys, but the exact mechanism for which is not clear. A two‐electron transition model is proposed.
TL;DR: In this paper, the Auger recombination effect on the threshold current of the InGaAsP quantum well (QW) laser is studied theoretically, and all possible transitions between the quantized subbands of two-dimensional carriers are taken into account in evaluating the radiative process with the k-selection rule and the augmentation process.
Abstract: The Auger recombination effect on the threshold current of the InGaAsP quantum well (QW) laser is studied theoretically. All possible transitions between the quantized subbands of two-dimensional carriers are taken into account in evaluating the radiative process with the k -selection rule and the Auger process. The calculated threshold current agrees well with the reported experimental results for 1.07 μm InGaAsP QW lasers. The Auger component of the threshold current and its temperature dependence strongly depend on the QW structure, resulting in the necessity for an elaborate QW structure design, although both cannot be optimized at the same time. A design procedure is elucidated for a structure which gives the lowest threshold current density for the 1.07, 1.3, and 1.55 μm InGaAsP QW lasers.
TL;DR: In this article, the optical gain characteristics of quantum well heterostructure lasers are investigated in a broad range from a weakly quantized system to a strongly quantized one utilizing the band-to-band model with k selection rule, the detailed band structure of the QH heterostructures, and degenerate statistics.
Abstract: Optical gain characteristics of quantum well heterostructure lasers are investigated in a broad range from a weakly quantized system to a strongly quantized one utilizing the band-to-band model with k selection rule, the detailed band structure of the quantum well heterostructures, and degenerate statistics. The results are compared to the experimentally observed threshold current densities in graded barrier single quantum well lasers. It is found that the threshold current densities of these quantum well lasers are well explained by the theoretical results in the range of well width from 75 to 300 A. The lowest threshold current density observed is 245 A/cm2in a heavily doped 100 A single quantum well laser with a 150μm stripe width and 550μm length.
TL;DR: In this article, a large variety of strained-layer quantum-well heterostructures (QWHs) and super-lattices (SLs) were grown by metalorganic chemical vapor deposition.
Abstract: Stimulated emission data are presented on a large variety of strained‐layer quantum‐well heterostructures (QWH’s) and superlattices (SL’s) grown by metalorganic chemical vapor deposition (MOCVD). These structures consist of barrier‐well combinations of thickness LB,Lz ≲150 A made from GaAs‐InGaAs, GaAsP‐GaAs, and GaAsP‐InGaAs. Also employed are higher band‐gap confining layers of InxAlyGa1‐x‐yAs, AlyGa1−yAs1−xPx, and AlxGa1−xAs. All of the heterostructures are grown on a GaAs substrate with and, in some cases, without a graded layer. The strain range between 0.2 to 12.5×10−3 is examined. Photopumped, these heterostructures operate as continuous (cw) 300 K lasers, with thresholds of 1.6–7.5×103 W/cm2, for periods of time between 0.5 to >35 min. Under high‐level excitation, the equivalent of Jeq∼103 A/cm2, laser operation fails or is quenched by networks of dislocations (with 〈110〉 Burger’s vectors) that are generated within the strained‐layer region of the QWH’s or SL’s. These dislocation networks, which a...
TL;DR: In this article, the effect of varying the buffer layer of the SQW on the photoluminescence intensity of a 65-A single quantum well was studied. But the effect was not studied.
Abstract: Ga0.47In0.53As/Al0.48In0.52As single quantum wells grown by molecular beam epitaxy have exhibited photoluminescence emission from 9668 A to the 1.55‐μm bulk emission at 4 K. The emission at 9668 A is 0.474 eV above the band gap of GaInAs. The single quantum well (SQW) is 15 A wide which is the narrowest SQW reported in any III‐V compound. The effect of varying the buffer layer of the SQW on the photoluminescence intensity of a 65‐A single quantum well is studied.
TL;DR: In this paper, the authors measured the gain and the carrier lifetime at threshold in shallow proton stripe AlGaAs multiquantum well lasers with several different active layer structures and found that the carrier density at threshold for the MMQW laser is about a factor of 4 lower than that for a single quantum well laser.
Abstract: We have measured the gain and the carrier lifetime at threshold in shallow proton stripe AlGaAs multiquantum well lasers with several different active layer structures. The lasers studied had active layers with two wells, four wells, six wells, and the modified multiquantum well. The net gain G is found to vary almost linearly with the injection current I for all the laser structures studied. The slope dG/dI is largest for the modified multiquantum well (MMQW) laser which is consistent with the observed lowest threshold current of these devices. We find that the carrier density at threshold for the MMQW laser is about a factor of 4 lower than that for a single quantum well laser. Thus, the effect of a nonradiative mechanism (e.g., Auger effect) which varies superlinearly with the injected carrier density is considerably reduced in MMQW lasers compared to that in single quantum well (SQW) lasers or the conventional double heterostructure lasers. The reduced threshold carrier density of the MMQW lasers has important implications for high temperature performance of lasers fabricated from the InGaAsP/InP material systems which are believed to have nonradiative mechanisms that vary superlinearly with carrier density, particularly for those laser structures for which the high temperature operation is not limited by leakage current.
TL;DR: In this article, transient capacitance measurements on double heterojunctions with a large quantum well active region (L z ∼800 A) were reported, and it was suggested that the thin GaAs layer acts as a "giant" artificial deep level.
Abstract: We report transient capacitancemeasurements on Al x Ga1−x As–GaAs–Al x Ga1 −x As (x∼0.35) double heterojunctions with a large quantum well active region (L z ∼800 A). It is suggested that the thin GaAs layer acts as a ‘‘giant’’ artificial deep level. It follows then that the band edge discontinuity ΔE c determines the electron emission rates (from the thin layer), thus making it possible for ΔE c to be determined by transient capacitancemeasurements.
Patent•
19 Sep 1983TL;DR: An integrated quantum well laser structure which has a plurality of quantum well lasers for providing plurality of light beams each having a different wavelength for use in wavelength division multiplexing was proposed in this article.
Abstract: An integrated quantum well laser structure which has a plurality of quantum well lasers for providing a plurality of light beams each having a different wavelength for use in wavelength division multiplexing.
TL;DR: In this paper, the optical waveguide absorption characteristics of MBE grown GaAs-AlGaAs doubleheterostructure wafers are studied by measuring edge luminescence under photoexcitation.
Abstract: Optical waveguide absorption characteristics of MBE grown GaAs–AlGaAs MQW doubleheterostructure wafers are studied by measuring edge luminescence under photoexcitation, and are compared with those of conventional GaAs DH wafers. The edge luminescence spectra show a double peak structure which is well explained by waveguide self-absorption, rather than by L0-phonon participation as has been suggested by other workers. The optical absorption loss of the unexcited MQW waveguide at its lasing wavelength is found to be much smaller than that for the conventional DH waveguide.
TL;DR: In this paper, the free carrier and intervalence band absorption in quantum-well structures has been investigated and potential application of the enhanced absorptions to near-infrared photodetectors is discussed.
TL;DR: In this article, an expression for the Auger recombination rate is derived for a particular process which is the quantum well equivalent of the so-called CCCH process with the carriers involved remaining in the lowest electron and hole subbands.
Abstract: The authors consider the problem of Auger recombination of electrons and holes in quantum well heterostructure. An expression for the Auger recombination rate is derived for a particular process which is the quantum well equivalent of the so-called CCCH process with the carriers involved remaining in the lowest electron and hole sub-bands. The recombining carriers are assumed to obey Boltzmann statistics. This restricted calculation is regarded as a useful preliminary to the study of the complete range of Auger processes in the quantum well, and the use of a Fermi-Dirac statistics.
TL;DR: In this paper, the properties of a GaAs/AlGaAs quantum well (QW) laser diode were studied under strong magnetic fields up to 30 Tesla and the spontaneous emission spectrum was found to shift toward the higher photon energy, following the shift \hbarωc/2 of the lowest Landau level.
Abstract: Characteristics of a GaAs/AlGaAs quantum well (QW) laser diode are studied for the first time under strong magnetic fields up to 30 Tesla. When field normal to QW plane is increased, the spontaneous emission spectrum is found to shift toward the higher photon energy, following the shift \hbarωc/2 of the lowest Landau level in the region of strong magnetic fields. Moreover, the emission spectrum is shown to be very little affected when magnetic fields are applied parallel to the QW plane. These results give evidence of light emission from a fully-quantized zero-dimensional carrier system in GaAs QW structures with strong magnetic fields normal to the QW plane.
TL;DR: In this article, the effects of a longitudinal electric field on the intrinsic and extrinsic photoluminescence of Be−doped GaAs−AlxGa1−xAs multiquantum well samples grown by molecular beam epitaxy have been investigated.
Abstract: Some effects of a longitudinal electric field on the intrinsic and extrinsic photoluminescence of Be‐doped GaAs‐AlxGa1−xAs multiquantum well samples grown by molecular beam epitaxy have been investigated. The principal sample exhibits four photoluminescence peaks whose relative intensities are observed to change in a very nonuniform manner with forward bias. As the forward bias is reduced (i.e., electric field increased) luminescence is shifted progressively from the free n=1 heavy hole exciton peak to the n=1 heavy hole exciton bound to Be0 peak to an n=1 confined electron‐Be0 peak. Changes in the integrated photoluminescence by more than two orders of magnitude are observed over the bias region studied. Shifts in the energy positions of the various peaks with bias are at most of the order of 1 meV.