MOVPE growth of InGaAs/GaAsP-MQWs for high-power laser diodes studied by reflectance anisotropy spectroscopy (original) (raw)
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MOCVD growth of strained multiple quantum well structure for 1.3 μm InAsP/InP laser diodes
Solid-State Electronics, 1999
In this article, we describe the growth and characterization for 1.3 mm InAsP/InP strained multiple quantum well (SMQW) laser diodes (LDs) with separate con®nement heterostructure grown at 5808C by metalorganic chemical vapor deposition. The grown strained single quantum well (SSQW) stack and strained multiple quantum well (SMQW) structures are characterized using double-crystal X-ray diraction and photoluminescence (PL) to con®rm the structural and optical qualities for practical device applications. The InAsP/InP SSQW stack grown at 5808C appears to be extremely abrupt, uniform, free of mis®t dislocations and narrow PL half width. Although the InAsP/ InP SMQWs grown at 5808C maintain its structural integrity throughout the deposition sequence, the slightly broader PL half width for InAsP/InP SMQW structure is attributed to the dislocations resulted from a large net strain. Laser emission can be achieved by using the InAsP/InP SMQWs and the lasing wavelength is in a good agreement with our designed structure. The experimental data of broad-area and ridge waveguide LDs are described in detail. #
High-Performance Strain-Compensated InGaAs–GaAsP–GaAs ( = 1:17 m) Quantum-Well Diode Lasers
This letter reports studies on highly strained and strain-compensated InGaAs quantum-well (QW) active diode lasers on GaAs substrates, fabricated by low-temperature (550 C) metal-organic chemical vapor deposition (MOCVD) growth. Strain compensation of the (compressively strained) InGaAs QW is investigated by using either InGaP (tensile-strained) cladding layer or GaAsP (tensile-strained) barrier layers. High-performance = 1 165 m laser emission is achieved from InGaAs-GaAsP strain-compensated QW laser structures, with threshold current densities of 65 A/cm 2 for 1500-m-cavity devices and transparency current densities of 50 A/cm 2 . The use of GaAsP-barrier layers are also shown to significantly improve the internal quantum efficiency of the highly strained InGaAs-active laser structure. As a result, external differential quantum efficiencies of 56% are achieved for 500-m-cavity length diode lasers.
Applied Physics Letters, 1996
We have studied the effects of substrate misorientation on the growth of strained-layer In 0.18 Ga 0.82 As quantum well laser structures with InGaAsP confinement layers and In 0.5 Ga 0.5 P cladding layers lattice matched to a GaAs substrate. Low-temperature photoluminescence ͑PL͒ and atomic force microscopy ͑AFM͒ provide evidence of a strong substrate-orientation dependence of the interface structure. The surface morphology of the InGaAs quantum well is found to be determined primarily by the underlying InGaAsP confinement layer. Structures grown on exact-͑100͒ oriented substrates exhibit three-dimensional island surface morphology, whereas growths on ͑100͒ substrates oriented 2°towards ͓110͔ exhibit high surface roughness, possibly due to step bunching. These observations correlate well with previously reported device performance from strained quantum well laser diodes in the InGaAs/InGaAsP/InGaP material system, and can serve as a tool to optimize device performance.
Impact of growth rate on the quality of ZNS-MQW InGaAsP/InP laser structures grown by LP-MOVPE
Journal of Electronic Materials, 2000
We investigated the influence of the growth rate on the quality of zero-netstrained InGaAsP/InGaAsP/InP multiquantum well structures for 1.55 µm emission grown by low pressure metalorganic vapor phase epitaxy. The samples consisted of fixed compressive strained wells (ε = +1%) and tensile strained barriers (ε = -0.5%) grown with different quaternary bandgap wavelengths (λ B = 1.1-1.4 µm). Using higher growth rates, we obtained for the first time high quality zero net strained multi quantum well structures, regardless having constant group V composition in the well and barriers. The samples were analyzed by x-ray diffraction, photoluminescence and atomic force microscopy techniques. The amplitude of surface modulation roughness along [011] direction decreased from 20 nm to 0.53 nm with increasing growth rate and/or quaternary compositions grown outside the miscibility gap. A new deep PL broad emission band strongly correlated with the onset of wavy layer growth is also reported. Broad area and ridge waveguide lasers with 10 wells exhibited low losses (34 cm -1 ) and low threshold current densities at infinite cavity length (1020 A·cm -2 and 1190 A·cm -2 , respectively).
Solid-State Electronics, 2002
In this article, we report the influence of InGaP barrier layer on the performance of 1.3 lm InAsP/InP/InGaP straincompensated multiquantum-well (SCMQW) laser diodes (LDs) grown by metalorganic chemical vapor deposition. Sharp satellite peaks with narrow width in double-crystal X-ray diffraction measurements and abrupt interface in secondary ion mass spectrometry analyses are observed, indicating that a good epitaxial-layer quality can be obtained through the use of strain-compensation coupled by InGaP barrier layers. By increasing InGaP barrier thickness to above 6 nm, a redshift of the photoluminescence peak is observed in the (1 0 0)-oriented strained layers. It is probably attributed to redistribution across the samples of the huge built-in electric field induced by the piezoelectric effect. The threshold current of InAsP/InP/InGaP SCMQW ridge-waveguide LDs decreases from 78.8 to 33.8 mA through the employ of tensile-strained InGaP barrier layer and the lasing wavelength is 1.307 lm under 44 mA. In addition, the experimental data of broad-area LDs for the InAsP/InP strained multiquantum-well and InAsP/InP/InGaP SCMQW structures are compared in detail. Ó
IEEE Journal of Quantum Electronics, 1999
In this paper, we study both experimentally and theoretically how the change of the p-doping profile, particularly the p-i junction placement, affects the output characteristics of 1.3-m InGaAsP-InP multiple-quantum-well (MQW) lasers. The relationship between the p-doping profile before and after regrowth is established, and the subsequent impact of changes in the p-i junction placement on the device output characteristics, is demonstrated. Device characteristics are simulated including carrier transport, capture of carriers into the quantum wells, the quantum mechanical calculation of the properties of the wells, and the solution for the optical mode and its population selfconsistently as a function of diode bias. The simulations predict and the experiments confirm that an optimum p-i junction placement simultaneously maximizes external efficiency and minimizes threshold current. Tuning of the base epitaxial growth Zn profile allows one to fabricate MQW devices with a threshold current of approximately 80 A/cm 2 per well for devices with nine QW's at room temperature or lasers with a characteristic temperature T 0 = 70 K within the temperature range of 20 C-80 C.
Brazilian Journal of Physics, 1999
Zero-Net-Strained ZNS InGaAsP InGaAsP InP Multi Quantum Wells MQW structures grown by L o w Pressure Metalorganic Vapor Phase Epitaxy for 1.55m laser applications were investigated using atomic force microscopy, photoluminescence spectroscopy and X-ray di raction. The morphology exhibits a strong anisotropic and modulated behavior. The photoluminescence spectrum shows a broad emission band below the fundamental quantum well transition. The results indicate a strong in uence of the growth rate, growth temperature and barrier composition on the surface morphology, and on the optical and structural properties of the ZNS structures. Ridge wave-guide ZNS-MQW laser structures grown at optimized conditions exhibited excellent electro-optic characteristics with low threshold current and high e ciency.
The growth of InGaAsP by CBE for SCH quantum well lasers operating at 1.55 and 1.4 μm
Journal of Crystal Growth, 1992
InGaAsP has been grown by CBE at compositions of 1.1, 1.2 and 1.4~sm for the development of MQW-SCH lasers. The observed incorporation coefficients for TMI and TEG show strong temperature sensitivity while the phosphorus and arsenic incorporation behavior is Constant over the substrate temperature range explored. 530 to 580°Csctpoint. For higher substrate temperatures the growth rate increases with the largest growth rates occurring for the 1.4 jcm quaternary. Low temperature photoluminescenee indicates the possibility of compositional grading or clustering for the 1.1 /sm material and also for the 1.2~ni material grown at the lowest substrate temperature. The final laser structure was grown with the loP cladding regions grown at 580°Cwith the inner cladding and active regions grown at 555°C. Using this approach we have successfully grown MQW-SCH lasers with the composition of the active In~Ga1 As ranging from x = 0.33 tox = 0.73. Threshold current densities as low as 689 A/cm 2 have been measured fir an 800~m~90~sm broad area device with x = 0.68.
Laser diodes with highly strained InGaAs MQWs and very narrow vertical far fields
physica status solidi (c), 2006
The effect of variation of the number of highly strained InGaAs quantum wells embedded in GaAs layers on the crystal quality of the epitaxial layers and AlGaAs/GaAs laser diodes was investigated. With four quantum wells and very thick waveguide layers, reasonable efficient laser diodes emitting above 1100 nm with a narrow vertical far field (FWHM = 15 °) were obtained. Broad area laser diodes with 200 µm stripe width and an optimised doping profile emit nearly 20 W cw output power.
Applied Physics Letters, 1995
3 W cw output power has been obtained from aluminum-free, strained-layer double-quantum well ͑DQW͒ InGaAs/InGaAsP/InGaP uncoated, 100-m-wide stripe diode lasers ͑ϭ0.945 m͒ grown by low-pressure MOCVD on exact ͑100͒ GaAs substrates. The combination of high-band-gap ͑1.62 eV͒ InGaAsP confinement layers and the DQW structure provides relatively weak temperature dependence for both the threshold current I th as well as the external differential quantum efficiency d . Furthermore, the series electrical resistance for 100 mϫ600 m stripe-contact devices is as low as 0.12 ⍀. As a result, the power conversion efficiency reaches a maximum of 40% at 8 ϫI th , and decreases to only 33% at the maximum power ͑i.e., 3 W͒ at 28ϫI th . Low-temperature ͑12 K͒ photoluminescence measurements of InGaAs/InGaAsP quantum-well structures exhibit narrow linewidths ͑Ͻ10 meV͒ for material grown on exact ͑100͒ GaAs substrates, while growths on misoriented substrates exhibit linewidth broadening, as a result of ''step bunching.'' Laser structures grown on misoriented substrates exhibit increased temperature sensitivity of both I th and d , compared with structures grown on exact ͑100͒ substrates.