Hydrogen effect on 670-nm AlGaInP visible laser during high temperature operation (original) (raw)
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Hydrogen effect on 670-nm AlGaInP visible laser during high temperature
Characteristic changes of single-mode 670-nm strained multiquantum-well (S-MQW) AlGaInP visible lasers during accelerated aging test are investigated. After a short-term continuous operation of 3mW at 50 C, the threshold current and slope efficiency are improved by 8.5% and 24%, espectively. In order to find out the origin of characteristic changes, photoluminescence and secondary ion mass spectrometry (SIMS) measurement were carried out. SIMS measurement revealed that atomic hydrogen, which had been formed as a zinc-hydrogen complex in the p-type InGaInP cladding layer, were dissociated and drifted into the active region of the laser structure during high temperature operation. These result in increase of the hole concentration of the p-AIGaInP layer, which enhances the heterobarrier height between the p-cladding layer and the active region. In addition, the dissociated atomic hydrogen drifted into the active region by bias voltage passivates the defects in that region, which is proved by low temperature photoluminescence measurement showing that the defect-related peaks are disappeared.
A 670nm AIGalnP/GalnP strained multi-quantum well laser diode with a high characteristic temperature (To) has been achieved by optimization of quantum well structures and the metal-organic chemical vapour deposition process. The hole concentration of 5 x 1017 cm -3 in the p-AIGalnP cladding layer on a (100) 5 ~ off GaAs substrate has been obtained with very small ratio, 0.35, of mole flow rate of zinc source to the group III sources ([DEZn]/[III]) of 0.35. The threshold current and maximum temperature for continuous wave operation of lasers with cavity length of 300 #m have been measured as 45 mA and 80~ respectively. The characteristic temperature (To) of the lasers has been measured as high as 153 K. The laser without facet protections could operate for more than 1000 h at 50~ and 5 mW.
Effect of annealing InGaP/InAlGaP laser structure at 950°C on laser characteristics
Journal of Nanophotonics, 2016
We achieved considerable laser diode (LD) improvement after annealing InGaP/ InAlGaP laser structure at 950°C for a total annealing time of 2 min. The photoluminescence intensity is increased by 10 folds and full-wave at half-maximum is reduced from ∼30 to 20 nm. The measured LDs exhibited significantly reduced threshold current (I th ), from 2 to 1.5 A for a 1-mm long LD, improved internal efficiency (η i ), from 63% to 68%, and increased internal losses α i , from 14.3 to 18.6 cm −1 . Our work suggests that the use of strain-induced quantum well intermixing is a viable solution for high-efficiency AlGaInP devices at shorter wavelengths. The advent of laser-based solid-state lighting (SSL) and visible-light communications (VLC) highlighted the importance of the current findings, which are aimed at improving color quality and photodetector received power in SSL and VLC, respectively, via annealed red LDs. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Canadian Journal of Physics, 2016
We report on the temperature-dependent spectral shifts in low power 670 nm AlGaInP multiple quantum well red laser diodes due to band gap narrowing at room temperatures (5–45 °C). The spectral shift mechanism is explored with a threshold current density of 11.41 kA/cm2 and a good characteristic temperature of 114 K. The photoluminescence peak intensity shifts towards higher wavelengths and the full width at half maximum increases with increase in temperature from 5 to 45 °C. We use a Hamiltonian system considering the effective mass approximation to formulate the carrier concentrations. The band gap narrowing value determined by a simple formula amounts to 59.15 meV and displays N1/3 dependence at higher densities. The carrier density dependence conveys that the redshift of the spectral emission is due to band gap narrowing.
Optik - International Journal for Light and Electron Optics, 2016
Spectral changes due to carrier induced band gap shrinkage for 675 nm AlGaInP multiple quantum well (MQW) laser diodes are studied at room temperatures (10-40) • C. The intensity peak shifted toward the lower energy and the full width at half maximum (FWHM) increases with the increase in temperature from 10 • C to 40 • C. The density of states effective mass approximation is employed to calculate the carrier concentrations. The bandgap shrinkage value amounts to 47.70 meV and shows N 1/3 dependence for higher concentrations. Through this it is observed that higher wavelength shifting of the spectral emission is due to the carrier induced band gap shrinkage. The spectral wavelength shift is interrogated with a low threshold current density of 6.28 kA/cm 2 .
Performance improvement of 650nm band AlGaInP laser diodes with optimal diffusion barriers
Materials Science and Engineering: B, 2006
GaInP/AlGaInP multiple quantum-well (MQW) laser diodes with diffusion barriers for Zn, grown by metal organic chemical vapor deposition (MOCVD), were fabricated and characterized. To determine the optimal conditions for the diffusion barriers, we investigated Zn diffusion in the GaInP/(Al 0.5 Ga 0.5 ) 0.5 In 0.5 P MQW layers against three undoped (Al 0.7 Ga 0.3 ) 0.5 In 0.5 P diffusion barriers with thicknesses of 0, 90, and 130 nm, respectively, by secondary ion mass spectroscopy (SIMS). Compared to the reference AlGaInP laser diode without a diffusion barrier, the AlGaInP ridge laser with a 130 nm thick diffusion barrier on the top of the MQW layer had a threshold current that was greatly reduced from 110 to 75 mA and the characteristic temperature T o that was increased from 113 to 144 K in the temperature range from 25 to 50 • C. This report presents quantitative information on the effect of Zn diffusion on laser performance.
Optical Materials, 2016
The temperature dependent spectral shifts in 658 nm AlGaInP multiple quantum well (MQW) red laser diodes due to band gap narrowing at room temperatures (5 Ce45 C) is reported. The density of states effective mass approximation and the conduction band effective mass approximation are employed to formulate the carrier concentrations. The spectral shift mechanism is explored with a threshold current density of 42.28 kA/cm 2 and a good characteristic temperature of 149 K. The photoluminescence (PL) peak intensity shifts towards the higher wavelength(red shift) and the full width at half maximum (FWHM) increases with the increase in temperature. The band gap narrowing value determined by a simple formula amounts to 67.4 meV and displays N 1/3 dependence at higher densities. The carrier density dependence conveys that the red shift of the spectral emission is due to band gap narrowing.
Low-threshold laterally oxidized GaInP-AlGaInP quantum-well laser diodes
IEEE Photonics Technology Letters, 1998
Low-threshold, high-efficiency edge-emitting visible AlGaInP-GaInP laser diodes using a buried AlAs native oxides for carrier and optical confinement are described. The lasers incorporate a thin AlAs layer in the upper cladding region, which when laterally wet oxidized, forms a narrow aperture. The lasers operate with room temperature, continuous-wave (CW) threshold currents of 11 mA with external differential quantum efficiency of 34% per facet for an uncoated 300-m-long 3.5-m-wide device. As-fabricated lasers exhibited modest performance under CW operation. Post-fabrication annealing was shown to dramatically improve the device characteristics.
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).