Jeng-Ya Yeh

Low-threshold 1317-nm InGaAsN quantum-well lasers with GaAsN barriers

Very low threshold-current-density InGaAsN quantum-well lasers with GaAsN barriers, grown using metalorganic chemical vapor deposition, have been realized with a room-temperature emission wavelength of 1317 nm. The GaAsN barriers are employed to extend the wavelength, to strain compensate the quantum well, and to improve the hole confinement inside the quantum well. RT threshold current densities of only 210–270 A/cm2 are measured for InGaAsN quantum-well lasers (Lcav=1000–2000 μm) with an emission wavelength of 1317 nm.

Experimental evidence of carrier leakage in InGaAsN quantum-well lasers

Carrier leakage processes are shown experimentally as one of the factors contributing to the temperature sensitivity of InGaAsN quantum well lasers. The utilization of the direct barriers of GaAs0.85P0.15 instead of GaAs, surrounding the InGaAsN quantum-well (QW)-active region, leads to significant suppression of carrier leakage at elevated temperatures of 90–100 °C. Threshold current densities of only 390 and 440 A/cm2 was achieved for InGaAsN QW lasers (Lcav=2000 μm) with GaAs0.85P0.15-direct barriers at temperature of 80 and 90 °C, respectively.

High-performance 1200-nm InGaAs and 1300-nm InGaAsN quantum-well lasers by metalorganic chemical vapor deposition

In this paper, we present the characteristics of high-performance strain-compensated MOCVD-grown 1200-nm InGaAs and 1300-nm InGaAsN quantum-well (QW) lasers using AsH/sub 3/ and U-Dimethylhydrazine as the group V precursors. The design of the InGaAsN QW active region utilizes an In-content of approximately 40%, which requires only approximately 0.5% N-content to realize emission wavelengths up to 1315-nm. Threshold current densities of only 65-90 A/cm/sup 2/ were realized for InGaAs QW lasers, with emission wavelength of 1170-1233 nm. Room-temperature threshold and transparency current densities of 210 and 75-80 A/cm/sup 2/, respectively, have been realized for InGaAsN QW lasers with emission wavelength of 1300-nm. Despite the utilization of the highly-strained InGaAsN QW, double-QW lasers have been realized with excellent lasing performance.

Extremely low threshold-current-density InGaAs quantum-well lasers with emission wavelength of 1215–1233 nm

Extremely low threshold-current-density In0.4Ga0.6As quantum-well (QW) lasers have been realized in the 1215–1233 nm wavelength regime. The measured room-temperature threshold current density of the InGaAs QW lasers with a cavity length of 1000 μm is only 90 A/cm2 at an emission wavelength of 1233 nm.

Physics and characteristics of high performance 1200 nm InGaAs and 1300–1400 nm InGaAsN quantum well lasers obtained by metal–organic chemical vapour deposition

Here we present the physics and device characteristics of high performance strain-compensated MOCVD-grown 1200 nm InGaAs and 1300–1400 nm InGaAsN quantum well (QW) lasers. Utilizing the GaAsP barriers surrounding the highly strained InGaAsN QW active regions, high performance QW lasers have been realized from 1170 nm up to 1400 nm wavelength regions. The design of the InGaAsN QW active region utilizes an In content of approximately 40%, which requires only approximately 0.5–1% N content to realize emission wavelengths up to 1300–1410 nm. Threshold current densities of only 65–90 A cm−2 were realized for InGaAs QW lasers, with emission wavelengths of 1170–1233 nm. Room temperature threshold and transparency current densities of 210 and 75–80 A cm−2, respectively, have been realized for 1300 nm InGaAsN QW lasers. Despite the utilization of the highly strained InGaAsN QW, multiple-QW lasers have been realized with excellent lasing performance. Methods for extending the lasing emission wavelength up to 1400 nm with InGaAsN QW lasers are also presented. Theoretical analysis and experiments also show suppression of thermionic carrier leakages in InGaAsN QW systems leading to high performance lasers operating at high temperature.

Nitrogen incorporation effects on gain properties of GaInNAs lasers: Experiment and theory

Gain properties of GaInNAs lasers with different nitrogen concentrations in the quantum wells are investigated experimentally and theoretically. Whereas nitrogen incorporation induces appreciable modifications in the spectral extension and the carrier density dependence of the gain, it is found that the linewidth enhancement factor is reduced by inclusion of nitrogen, but basically unaffected by different nitrogen content due to the balancing between gain and index changes.

Effect of nitrogen on gain and efficiency in InGaAsN quantum-well lasers

We compare the gain and radiative efficiency characteristics of an InGaAsN and an InGaAs laser structure where the devices are identical except for the nitrogen content and emission wavelength. We find that the inclusion of nitrogen has little impact on the gain spectra except for the required shift to longer wavelength and that the intrinsic gain-radiative current characteristics may be slightly better for the nitrogen-containing materials. The radiative efficency is reduced by a factor of 4 in the samples containing nitrogen due to increased nonradiative recombination.

Long wavelength emission of InGaAsN∕GaAsSb type II “W” quantum wells

Low temperature (30K) long wavelength photoluminescence emission (λ=1400–1600nm) from metalorganic chemical vapor deposition grown InGaAsN–GaAsSb type II “W” quantum wells (QWs), on GaAs substrates has been demonstrated. Thin layers (2–3nm) and high antimony-content (30%) GaAsSb were utilized in this study for realizing satisfactory wave function overlap and long wavelength emission. Tensile strained GaAsP barriers effectively improve the material structural and luminescence properties of the compressive strained active region. Room temperature photoluminescence data show that the type-II QW design is a promising candidate for realizing long wavelength GaAs-based diode lasers beyond 1500nm.

Temperature-sensitivity analysis of 1360-nm dilute-nitride quantum-well lasers

The N-content of an InGaAsN quantum-well (QW) laser is found to dramatically affect the temperature sensitivity of the current injection efficiency (/spl eta//sub inj/) and material gain parameter (g/sub oJ/). The increased temperature sensitivity of /spl eta//sub inj/ and g/sub oJ/ of InGaAsN QW lasers with increasing N-content leads to a significant increase in their temperature sensitivity of threshold current and external differential quantum efficiency. Increasing the N-content of the InGaAsN QW potentially results in a reduction of the heavy hole confinement, which may account for the increased temperature sensitivity of the current injection efficiency.

MOCVD-Grown Dilute Nitride Type II Quantum Wells

Dilute nitride Ga(In)NAs/GaAsSb ldquoWrdquo type II quantum wells on GaAs substrates have been grown by metal-organic chemical vapor deposition (MOCVD). Design studies underscore the importance of nitrogen incorporation to extend the emission wavelength into the 1.5 mum region as well as increase the electron confinement, given the material strain relaxation limitations. These studies also indicate that the Sb content of the GaAs1-xSbx hole well is required to be greater than x ~ 0.2, to provide adequate hole confinement (i.e., DeltaEnu > 150 meV). Photoluminescence (PL) and electroluminescence (EL) studies are used to characterize the optical transitions and compare with a ten-band \bm k.p simulation. We find that the lowest energy type II transition observed is in good agreement with theory. Preliminary results are presented on diode lasers with two- and three-stage ldquoWrdquo-active regions that exhibit emission that is blue-shifted from the PL, due to charge separation and carrier band-filling of higher energy transitions. Further structure optimization, including multiple-stage (eight to ten W-stages) active regions is required to lower the threshold carrier density and minimize carrier band-filling and built-in electric field effects resulting from charge separation. Dilute nitride materials, such as GaAs1- y-z Sby Nz /InP, are also under development offering potential for wavelength extension into the mid-IR employing InP substrates.