K. Hiramoto

High-power highly-reliable operation of 0.98-/spl mu/m InGaAs-InGaP strain-compensated single-quantum-well lasers with tensile-strained InGaAsP barriers

We compared 0.98-/spl mu/m lasers with a strain-compensated active layer consisting of a compressive InGaAs well and tensile-strained InGaAsP barriers with identical lasers that have a conventional active layer with GaAs barriers. It was shown that the lasers with InGaAsP barriers have better temperature characteristics due to the larger energy gap difference between a well and barriers. Because of the high characteristic temperature, 200-mW operation was obtained with the InGaAsP-barrier laser even at 90/spl deg/C without any significant deterioration. We also showed that the operation of the lasers with a strain-compensated active layer was highly reliable. The degradation rate of these lasers was four times smaller than that of the lasers with GaAs barriers due to the better crystal quality in their active laser. The estimated lifetime at 25/spl deg/C for the lasers with a strain-compensated active layer was more than 170000 hours. >

Multistep formation and lateral variation in the In composition in InGaAs layers grown by metalorganic vapor phase epitaxy on (001) vicinal GaAs substrates

Abstract In this paper, we investigate the substrate misorientation effect on In 0.2 Ga 0.8 As/GaAs strained quantum wells grown on vicinal GaAs substrates by metalorganic vapor phase epitaxy (MOVPE). Using cross-sectional transmission electron microscopy (TEM), stepbunching in an InGaAs layer is observed. In addition, based on energy-dispersive X-ray (EDX) analysis, we report for the first time lateral variations in the In composition in an InGaAs layer grown on a vicinal substrate. It is found that this variation in In composition and variations in the thickness cause photoluminescence (PL) spectrum broadening. The dependence of PL properties on the growth conditions and on surface misorientation direction is also examined. Experimentals results are explained by discussing the diffusion length of Group III atoms and their tendency to attach to step sites. TEM analysis confirms that the critical layer thickness of an InGaAs layer decreases on a vicinal substrate due to the formation of stepbunches.

High-power and highly reliable operation of Al-Free InGaAs-InGaAsP 0.98-/spl mu/m lasers with a window structure fabricated by Si ion implantation

We have fabricated Al-free InGaAs-InGaAsP-GaAs strained quantum-well 0.98-/spl mu/m lasers with a window structure. The window structure was obtained by Si ion-implantation-induced QW intermixing. The photoluminescence and photocurrent measurements show that an implantation energy of 100 keV and a dose of 1E13 cm/sup -2/ are enough for the fabrication of the window structure in our laser structure. The threshold current of the fabricated 0.98-/spl mu/m lasers with a window structure is 20 mA and a stable lateral mode is obtained up to 300 mW, and these results suggest that there is no scattering loss or absorption due to the introduction of a window structure. The reliability of the lasers is greatly improved by the introduction of the window structure: they exhibited stable operation for more than 1000 h at 240-mW output power at 50/spl deg/C. And this results gives us an estimated lifetime of more than 200 000 h at 25/spl deg/C.

Enhanced optical crystal quality of strain-compensated InGaAs/InGaAsP quantum-well structures on GaAs substrates by the introduction of intermediate-strain layers

To improve the crystal quality of heterointerfaces in InGaAs/InGaAsP strain-compensated quantum-well structures on [001] GaAs substrates, we added layers with intermediate levels of strain between the well and barriers. Photoluminescence measurements confirmed that the crystal quality of the heterointerfaces was improved by adding these intermediate layers. The greatest improvement was attained with an intermediate layer thickness of 4 monolayers and a strain at about the midpoint between that of QWs and barriers. The mean time to failure of fabricated 0.98-/spl mu/m laser diodes (LDs) with such intermediate-strain layers was found to be about five times longer than that of LDs without the intermediate-strain layer.

Reduced lattice distortion in and near strain-compensated InGaAs/InGaAsP multiple-quantum well structures grown by metal-organic vapor phase epitaxy on GaAs substrates

We have investigated strain-compensated InGaAs/InGaAsP multiple-quantum well (MQW) structures grown by metal-organic vapor phase epitaxy on [001] GaAs substrates, by using photoluminescence (PL) measurements and transmission electron microscopy (TEM). It was found that the lattice distortion in and near the MQW structures caused by compressive strain in InGaAs wells was reduced far below the levels of ordinary InGaAs/GaAs MQW structures when tensile-strain InGaAsP barriers were introduced. Furthermore we have fabricated 0.98-/spl mu/m laser diodes (LDs) with the strain-compensated QW active layer, and found that the mean time to failure of such LDs is expected to be three to four times longer than that of LDs with ordinary GaAs barriers.