Showing papers on "Quantum well published in 1981"
TL;DR: A variational calculation of hydrogenic impurity states in a quantum well has been performed in this article, where the binding energy of donor (acceptor) levels is calculated as a function of layer thickness and of the impurity position.
Abstract: A variational calculation of hydrogenic impurity states in a quantum well has been performed. The binding energy of donor (acceptor) levels is calculated as a function of layer thickness and of the impurity position. It is found that the ground impurity state degeneracy with respect to the impurity position is lifted, leading to the formation of some sort of an "impurity band." The density of states of this impurity band exhibits one or two peaks energetically located at the "band" extrema. This one-dimensional feature can be evidenced in the optical absorption associated with valence subband\ensuremath{\rightarrow}donor transitions, whereas acceptor\ensuremath{\rightarrow}conduction processes are almost featureless. In the case of conduction\ensuremath{\rightarrow}acceptor luminescence a smooth curve is obtained for degenerate electronic distribution, whereas nondegenerate electron\ensuremath{\rightarrow}trapped hole recombination spectra should again exhibit a double peak.
778 citations
TL;DR: In this paper, a systematic increase of the linewidth of luminescence, absorption and excitation spectra of undoped GaAs-Ga 1-x A l x As Multi-Quantum structures with decreasing layer thickness was reported.
327 citations
TL;DR: In this article, Raman measurements on a new type of superlattice consisting of $n$-and $p$-type doped GaAs layers grown by molecular-beam epitaxy confirm crucial predictions of theory.
Abstract: Luminescence and Raman measurements on a new type of superlattice consisting of $n$- and $p$-type doped GaAs layers grown by molecular-beam epitaxy confirm crucial predictions of theory. A strongly tunable energy gap is found in luminescence. Raman experiments provide the first observation of electronic subbands in purely space-charge-induced quantum wells. A combined analysis of the luminescence and Raman data yields excellent agreement with self-consistent subband calculations based only on the design parameters of the sample.
133 citations
TL;DR: In this article, the high-energy photpumped laser operation of AlxGa1−xAs−AlAs•AlAs−GaAs quantum-well heterostructures grown by metalorganic chemical vapor deposition (MO‐CVD) is described.
Abstract: The high‐energy (visible‐red) photpumped laser operation (6345 A at 77 K, 6785 A at 300 K) of AlxGa1−xAs‐AlAs‐GaAs quantum‐well heterostructures (QWH) grown by metalorganic chemical vapor deposition (MO‐CVD) is described. The QWH active regions are alloy‐free and consist of GaAs quantum wells and AlAs barrier layers. The effect of the AlAs barrier‐layer thickness on the energy banding of the confined‐carrier states and transitions is demonstrated. The laser operation of the coupled GaAs quantum wells is observed as high as 400–445 meV above the bulk‐GaAs band edge, which agrees with the calculated locations (Lz∼30 A) of the lowest (n = 1) electron, heavy‐hole, and light‐hole confined‐particle states or energy bands.
78 citations
TL;DR: In this paper, the fabrication procedure, electrical properties, optical-bean characteristics, spectral characteristics, and temperature dependence of emission wavelength and threshold of InGaAsP buried-heterostructure (BH) lasers emitting at 1.3 μm are described.
Abstract: The fabrication procedure, electrical properties, optical-bean characteristics, spectral characteristics, and temperature dependence of emission wavelength and threshold of InGaAsP buried-heterostructure (BH) lasers emitting at 1.3 μm are described. The dimensional requirements for fundamental-transverse mode operation have been determined. BH devices are characterized by low threshold currents, fundamental transverse mode operation, linear light output, and narrow spectral width. For 380 μm long devices threshold currents of 40 mA, slope efficiencies of 18 percent, forward resistance of 5 Ω, and T 0 values of 75 K have been attained.
66 citations
TL;DR: In this paper, a single longitudinal mode operation over twice the threshold current is obtained with high quantum efficiency by optimizing the coupling properties and configurational parameters of the DBR-ITG laser.
Abstract: Lasing characteristics of 1.5-1.6 \mu m GaInAsP/InP integrated twin-guide lasers with first-order distributed Bragg reflectors (DBR-ITG lasers) are given theoretically and experimentally. At this wavelength region the fiber loss is ultimately low, but the effect of the material dispersion is serious. It is theoretically found that single longitudinal mode operation over twice the threshold current is obtainable with high quantum efficiency by optimizing the coupling properties and configurational parameters of the DBR-ITG laser. The experimental results are also demonstrated. Single longitudinal mode operation of 1.5-1.6\mu m DBR-ITG lasers under high-speed direct modulation was achieved with a pulsewidth of 1.5 ns.
58 citations
TL;DR: In this paper, a simple analytical expression for the reflectivity of the cleaved facets of DH semiconductor lasers is compared with numerical results, and reasonable agreement is found. But the analytical result is conveniently written in terms of waveguide parameters and thus gives a valuable tool for analysis of DH lasers.
Abstract: A simple analytical expression for the reflectivity of the cleaved facets of DH semiconductor lasers is compared with numerical results, and reasonable agreement is found. The analytical result is conveniently written in terms of waveguide parameters and thus gives a valuable tool for analysis of DH lasers.
49 citations
TL;DR: In this paper, the authors summarized the work done on transversely excited (TE) waveguide lasers since the first proposal in 1973 and reported on the current state of the art, and described the development of waveguide designs and of techniques for discharge control which permit high-pressure operation and high output power densities.
Abstract: This paper summarizes the work done on transversely excited (TE) waveguide lasers since the first proposal in 1973 and reports on the current state of the art. We describe the development of waveguide designs and of techniques for discharge control which permit high-pressure operation and high output power densities to be obtained.
48 citations
TL;DR: In this article, it was shown that the new peaks correspond to the recombination of electrons in excited well states, n≳1, with holes in n = 1 states.
Abstract: When GaAs quantum wells are optically excited with intensities ≳10 kW/cm2 new peaks appear in the photoluminescence spectrum at low temperatures. The excitation spectra are used to demonstrate that the new peaks correspond to the recombination of electrons in excited well states, n≳1, with holes in n = 1 states. These parity‐forbidden transitions, Δn odd, derive their strength from three body interactions that occur at high excitation levels.
39 citations
TL;DR: In this paper, the authors describe the general growth of Ga1−xAlxAs by metalorganic chemical vapor deposition (MO-CVD) with specific application to quantum well heterostructure (QWH) transport structures.
34 citations
TL;DR: In this article, the photoluminescent and excitation spectra showed no evidence of clustering, in marked contrast to results on a similar structure grown by metal-organic chemical vapor deposition.
Abstract: A heterostructure, consisting of two GaAs quantum wells each of 40 A width separated by a 40‐A Al0.5Ga0.5As barrier, has been grown by molecular beam epitaxy and examined optically for Al‐Ga disorder (alloy clustering). The photoluminescent and excitation spectra showed no evidence of clustering, in marked contrast to results on a similar structure grown by metal‐organic chemical vapor deposition. Thus any clusters present must be less than 40 A in diameter. The spectra also support an island‐like interface with steps of ∼one monolayer in height and ≳300 A in lateral extent.
TL;DR: In this paper, an AlxGa1−xAs−AlAs•AlAs−GaAs•GaAs quantum-well heterostructure (QWH) was grown by metalorganic-chemical vapor deposition with an active region consisting of 13 AlAs barrier layers of size LB∼10 A and 12 GaAs quantum wells of size Lz∼50 A.
Abstract: Laser data (77 and 300 K) are presented on an AlxGa1−xAs‐AlAs‐GaAs quantum‐well heterostructure (QWH) grown by metalorganic‐chemical vapor deposition with an active region consisting of 13 AlAs barrier layers of size LB∼10 A and 12 GaAs quantum wells of size Lz∼50 A. This QWH, which is free of alloy disorder and clustering (Al‐Ga clusters) in the active region, emits on the confined particle transitions and not at the lower energies characteristic of QWH’s with AlxGa1−xAs barrier layers (and Al‐Ga clusters).
TL;DR: In this paper, singlemode operation and significant reduction in threshold has been observed in cleaved short-cavity (50-75 μm) stripe-geometry injection lasers with deposited metallic mirrors.
Abstract: Single-mode operation and significant reduction in threshold has been observed in cleaved short-cavity (50–75 μm) stripe-geometry injection lasers with deposited metallic mirrors.
TL;DR: In this paper, an X-ray diffraction technique was used to measure the well width of a GaAs superlattice with an accuracy of 10% and showed that the main carrier recombination process at room temperature is from the n = 1 electron quantum level to the n= 1 heavy hole level.
Abstract: AlAs/GaAs superlattices were grown by molecular beam epitaxy with a GaAs quantum well width Lz of 20–160 A. An X-ray diffraction technique is shown to be a practical and non-destructive method to measure Lz with in an accuracy of 10%. A photoluminescence measurement showed a sharply peaked structure (ΔE 50 meV) and indicated that the main carrier recombination process at room temperature is from the n=1 electron quantum level to the n=1 heavy hole level. Carrier concentration dependence of the photoluminescence energy differs from the usual Burstein-Moss shift. The highest emission energy obtained was 1.77 eV (7000 A).
TL;DR: In this paper, high temperature characteristics of stripe-geometry InGaAsP/InP double-heterostructure lasers with an emission wavelength of 1.3μm were presented.
Abstract: This paper presents high temperature characteristics of stripe-geometry InGaAsP/InP double-heterostructure lasers with an emission wavelength of 1.3μm. To evaluate how thermal characteristics such as heat dissipated power, thermal resistance, and temperature increase in the quaternary active region contribute to CW operation, and to derive conditions for stable operation at high temperatures, these thermal characteristics were analyzed for gain-guiding lasers and refractive index-guiding lasers as a function of stripe width and cavity length. Using proton bombarded lasers and self-aligned lasers, oscillation behavior was examined at above room temperature and compared with the analytical results.
TL;DR: In this article, the important experimental parameters affecting the mode locking of a variety of (GaAl)As injection lasers operating in an external optical cavity were described, and the experimental results appeared to imply that mode locking in injection lasers is related to laser defects and is very similar to passive mode-locking in dye lasers.
Abstract: This paper describes the important experimental parameters affecting the mode locking of a variety of (GaAl)As injection lasers operating in an external optical cavity We find that short detector limited pulses (less than 60 ps) and 100 percent modulation depth can only be obtained using lasers which exhibit either an anomalous narrow-band noise or self-pulsations Little or no mode locking is observed in lasers having the normal broad noise resonance The observed amplitude, pulsewidth, and frequency of the mode-locked pulses are correlated to the degree of self-pulsation and the external cavity length The experimental results obtained are in qualitative agreement with a model which uses the rate equations modified by either electron traps or saturable absorbers and a delayed feedback term Our results appear to imply that mode locking in injection lasers is related to laser defects and is very similar to passive mode locking in dye lasers
TL;DR: In this article, the low-threshold continuous room-temperature laser operation of a photopumped metalorganic chemical vapor deposition AlxGa1−x As−GaAs superlattice is described.
Abstract: The low‐threshold continuous room‐temperature laser operation of a photopumped metalorganic chemical vapor deposition AlxGa1−x As‐GaAs superlattice is described. The superlattice, a bare superlattice without cladding or confining layers, consists of 25 140‐A AlxGa1−x As (x∼0.3) coupling barriers doped to a level nd ∼7×1017/cm3 and 25 alternating undoped 140‐A GaAs quantum wells. Low‐temperature data (77 K) are presented indicating that the threshold for phonon‐assisted recombination occurs near the excitation level at which the excess carrier density approaches the built‐in carrier density ∼7×1017/cm3 of the superlattice.
TL;DR: In this article, the authors present measurements of the radiation field, the mode spectrum, and the power characteristic of narrow-stripe (5 μm) proton-bombarded DH GaAs-AlGaAs injection lasers.
Abstract: We present measurements of the radiation field, the mode spectrum, and the power characteristic of narrow-stripe (5 μm) proton-bombarded DH GaAs-AlGaAs injection lasers. We show that there is a correlation of these properties with the presence of self-oscillations. We conclude that lasers that display self-oscillations have a different lateral gain distribution from lasers that do not oscillate. With a simple three-by-three layer rectangular waveguide laser model we simulate the properties of the radiation field. We extend the model to include time-dependent carrier densities and a time-dependent number of photons in the mode. From the calculated response to fluctuations in current and spontaneous emission we explain the occurrence of self-oscillations and their dependence on the waveguide geometry.
TL;DR: In this article, the effects of alloy clustering in AlxGa1−xAs−GaAs quantum-well heterostructures (QWHs) grown by molecular-beam epitaxy (MBE) are investigated.
Abstract: The effects of alloy clustering in AlxGa1−xAs‐GaAs quantum‐well heterostructures (QWH’s) grown by molecular‐beam epitaxy (MBE) are investigated. Both low‐ and high‐level photoluminescence data on three of the best MBE QWH lasers are presented. These data indicate that while clustering in AlxGa1−xAs can depend on crystal growth conditions (temperature, stoichiometry, surface chemistry, contamination, etc.), it is to an appreciable extent intrinsic to the alloy. Clustering in AlxGa1−xAs can result from the random distribution of Al and Ga atoms regardless of the method of crystal growth. In addition, this work demonstrates cw 300‐K photopumped laser operation of MBE QWH’s, which would not be possible if the distributed and heterointerface defect densities (of unknown amount) were very high.
TL;DR: In this paper, the transient and noise characteristics of single and multiple-quantum-well heterostructure lasers grown by metalorganic-chemical vapor depostion have been investigated, and it has been shown that under dc excitation the quantum shot noise resonance is much less than that of standard double heterostructures of comparable stripe widths.
Abstract: The transient and noise characteristics of single and multiple‐quantum‐well heterostructure lasers grown by metalorganic‐chemical vapor depostion are investigated. In pulsed operation these lasers do not exhibit damped relaxation oscillations and under dc excitation the quantum shot noise resonance is much less than that of standard double heterostructure lasers of comparable stripe widths.
TL;DR: In this article, an estimate of the electron-phonon coupling coefficient for indirect optical transitions is presented, indicating enhanced coupling with increased phonon density and establishing a basis for stimulated phonon emission in QWH's.
TL;DR: The properties of diffused PbSnSe homojunction diode lasers based on the confinement of injected carriers and of light in the fundamental transverse laser mode are investigated both theoretically and experimentally.
Abstract: The properties of diffused PbSnSe homojunction diode lasers based on the confinement of injected carriers and of light in the fundamental transverse laser mode are investigated both theoretically and experimentally. The electrostatic potential profile near the graded junction is evaluated for the strongly forward biased case. Resulting injection and gain profiles are narrow and their widths increase with temperature. Free carrier dispersion leads to an optical confinement. From the threshold condition for the TEM 00 mode, the threshold current density is obtained, assuming a minority carrier lifetime of 2 ns. PbSnSe diode lasers were fabricated by diffusion of cadmium under different conditions. Experimental laser properties for different junction gradings are discussed in terms of the model. Threshold currents and output powers as a function of temperature, as well as maximum operating temperature and mode behavior, are consistent with the theoretical expectations.
TL;DR: In this article, a series of experiments have been conducted to determine the extent of longitudinal optical phonon contribution to quantum-well-heterostructure (QWH) laser opertion, and extensive data are presented on metalorganic chemical vapor deposited (MO-CVD) AlxGa1−x As-GaAs QWHs with active regions consisting of larger quantum wells, or in some cases bulk layers (Lz≳500 A), coupled to phonongenerating and reflecting arrays of coupled smaller quantum wells.
Abstract: A series of experiments have been conducted to determine the extent of longitudinal optical (LO) phonon contribution to quantum‐well‐heterostructure (QWH) laser opertion. Extensive data are presented on metalorganic chemical vapor deposited (MO‐CVD) AlxGa1−x As‐GaAs QWH’s with active regions consisting of larger quantum wells, or in some cases bulk layers (Lz≳500 A), coupled to phonon‐generating and ‐reflecting arrays of coupled smaller quantum wells. Because of the electronic and vibrational coupling of the single larger layer to the array, the spontaneous emission and laser emission from these structures differ from that of QWH’s containing either a single well or a multilayer of uniform well thickness. In fact, phonon sideband laser operation of the larger GaAs layer can be induced at h/w∼Eg‐h/wLO (undoped layers, nd−na≲1015 /cm3). An increase in either the thermal or nonthermal phonon occupation number is shown to cause phonon sideband laser operation in a QWH. A guide to the design of the multilayer...
TL;DR: In this paper, the authors show that quantum-well size changes δLz = δLB can be observed, via luminescence or laser spectral shifts, on all-binary, active region (AlAs•GaAs) QWHs or superlattices (SLs) with coupling barrier sizes LB <50 A.
Abstract: In AlxGa1−x As‐GaAs quantum‐well heterostructures (QWH’s) or superlattices (SL’s) with coupling barrier sizes LB <50 A, alloy clustering, owing simply to fluctuations in the random Al‐Ga arrangement, causes effective changes in quantum‐well size and, as a consequence, a decrease in energy and broadening of the confined‐particle states. Data are presented showing that actual quantum‐well size changes δLz = δLB can be observed, via luminescence or laser spectral shifts, on all‐binary, active‐region (AlAs‐GaAs) QWH’s or SL’s. The small spectral broadening and downward shift indicate a size change δLz = δLB as small as a monolayer for high‐energy, all‐binary QWH and SL structures grown by metal‐organic chemical vapor deposition. Narrow‐spectrum cw 300‐K laser operation has been realized at λ∼7500 A, and should be possible to λ≲6785 A.
TL;DR: In this paper, a design for a double-heterostructure diode laser with low threshold current (40-50 mA) and high differential quantum efficiency (50-65 percent) that operates stable single lowest order (TE 00 ) spatial mode to powers well in excess of 50 mW is presented.
Abstract: Light versus current ( L versus I ) characteristics are calculated for double-heterostructure diode lasers whose active regions decrease in thickness laterally from a maximum on axis. This variation produces lateral real refractive index waveguiding which in turn stabilizes the spatial mode such that the modal field becomes anastigmatic and the L versus I plot becomes linear. In addition to determining threshold current and differential quantum efficiency, we compute the TE 00 mode patterns, active region charge density distribution, and the power level P*_{1} at which spatial hole burning causes the TE 01 mode to begin lasing. The maximum power density at the facet for that power level P*_{1} is also obtained. All these characteristics are presented as functions of the various device parameters including carrier spontaneous recombination time, diffusion length, optical gain, unpumped band-to-band absorption, internal losses, antiguidance index, wavelength, cladding Al content, active region dimensions, current spreading resistance, facet reflectivity, laser length, and stripe width. Utilizing this information, a design is developed for a laser with low threshold current (40-50 mA) and high differential quantum efficiency (50-65 percent) that operates stable single lowest order (TE 00 ) spatial mode to powers well in excess of 50 mW.
TL;DR: In this paper, it was shown that a sufficiently heavily pumped quantum well laser, lead to the buildup of such a high phonon population that phonon assisted laser action by doubly stimulated emission of photons and phonons acquires a higher gain than unassisted laser action.
Abstract: The dissipation processes by which electrons and holes lose energy after being trapped in quantum wells might, in a sufficiently heavily pumped quantum well laser, lead to the buildup of such a high phonon population that phonon‐assisted laser action by doubly stimulated emission of photons and phonons acquires a higher gain than unassisted laser action. The resulting mode switching exhibits a pronounced hysteresis with pump rate, which should be a characteristic identifying feature of phonon‐assisted laser action.
TL;DR: In this paper, the authors performed high frequency (0.02-1.8 GHz) noise power measurements of both index-and gain-guided DH (AlGa)As injection lasers were carried out by means of single detector equipment.
Abstract: High-frequency (0.02-1.8 GHz) noise power measurements of both index- and gain-guided DH (AlGa)As injection lasers were carried out by means of single detector equipment. The index-guided structures include a new diffused index-guided type and some channeled substrate planar (CSP) structures, whereas the gain-guided lasers all have a stripe defined by proton bombardment, but they differ in the width of their stripe ( 2.5-10 \mu m) and the depth of the bombardment. From the measurements it was concluded ihat although, generally speaking, index-guided lasers show the lowest intensity noise level, the gain-guided lasers can approach this level, provided that their structure is optimized. The results of some of the various types of lasers studied are compared qualitatively with predictions of McCumber's theory.
TL;DR: In this paper, the variation of the threshold current density and its temperature dependence with acceptor concentration in GaInAsP/InP lasers emitting at 1.3 μm is described.
Abstract: The variation of the threshold current density and its temperature dependence with acceptor concentration in GaInAsP/InP lasers emitting at 1.3 μm is described. Mechanisms responsible for the dependence are identified. A model is developed to predict the effect of the above dependence on the CW operation range of these devices. The validity of the model is verified experimentally.
TL;DR: In this paper, photoluminescence data, at low and high excitation levels (pulsed and c.w., 300 and 77 K), are presented on Al x Ga 1− x As GaAs quantum-well heterostructures (QWH's) grown by molecular beam epitaxy (MBE).
TL;DR: In this article, self-sustained pulsations, superlinear emission, and negative-resistance behavior of 1.3μm InGaAsP stripe-geometry double-heterostrueture lasers are studied as a function of temperature and drive current.
Abstract: Self-sustained pulsations, superlinear emission, and negative-resistance behavior of several 1.3μm InGaAsP stripe-geometry double-heterostrueture lasers are studied as a function of temperature and drive current. The pulsations are observed in a certain current range above threshold. This current range increases with increasing temperature. Also, the maximum modulation, in general, increases with increasing temperature. All devices exhibiting superlinear emission were found to pulsate. The external differential quantum efficiency in the region of superlinear emission was found to increase with increasing temperature and the magnitude of the negative resistance decreased with increasing temperature. These phenomenon are predominantly observed in nitride-stripe or oxide-stripe lasers. Superlinear emission and negative-resistance behavior have not been observed in buried-waveguide lasers. The behavior of InGaAsP nitride-defined stripe lasers is found to be similar to that previously reported for proton-bombarded AlGaAs lasers.