K.C. Yew

High-temperature operation of self-assembled GaInNAs/GaAsN quantum-dot lasers grown by solid-source molecular-beam epitaxy

Self-assembled GaInNAs∕GaAsN single layer quantum-dot (QD) lasers grown using solid-source molecular-beam epitaxy have been fabricated and characterized. Temperature-dependent measurements have been carried out on the GaInNAs QD lasers. The lowest obtained threshold current density in this work is ∼1.05kA∕cm2 from a GaInNAs QD laser (50×1700μm2) at 10°C. High-temperature operation up to 65°C was also demonstrated from an unbonded GaInNAs QD laser (50×1060μm2), with high characteristic temperature of 79.4K in the temperature range of 10–60°C.

Self-assembled GaInNAs/GaAsN quantum dot lasers: solid source molecular beam epitaxy growth and high-temperature operation

Self-assembled GaInNAs quantum dots (QDs) were grown on GaAs (001) substrate using solid-source molecular-beam epitaxy (SSMBE) equipped with a radio-frequency nitrogen plasma source. The GaInNAs QD growth characteristics were extensively investigated using atomic-force microscopy (AFM), photoluminescence (PL), and transmission electron microscopy (TEM) measurements. Self-assembled GaInNAs/GaAsN single layer QD lasers grown using SSMBE have been fabricated and characterized. The laser worked under continuous wave (CW) operation at room temperature (RT) with emission wavelength of 1175.86 nm. Temperature-dependent measurements have been carried out on the GaInNAs QD lasers. The lowest obtained threshold current density in this work is ∼1.05 kA/cm2from a GaInNAs QD laser (50 × 1,700 µm2) at 10 °C. High-temperature operation up to 65 °C was demonstrated from an unbonded GaInNAs QD laser (50 × 1,060 µm2), with high characteristic temperature of 79.4 K in the temperature range of 10–60 °C.

Studies of In and N composition effects on the optical properties and surface morphology of GaInNAs quantum dots grown by rf-plasma assisted MBE

Self-assembled GaInNAs quantum dots (QD) were fabricated on GaAs [001] substrate by solid source molecular beam epitaxy (SSMBE) equipped with a RF nitrogen plasma source. The surface morphology was investigated using atomic-force microscopy (AFM), and the photoluminescence (PL) of the QDs was measured at low temperature (5 K). Through these measurements, the effect of indium and nitrogen compositions on the island density, island size, and optical properties were studied. The experiment was carried out with indium and nitrogen composition ranges of 30%-70% and 0.4%-0.8%, respectively. Using high indium composition, an island density of 1/spl times/1/sup 01/1/cm/sup 2/ was obtained in a single layer of GaInNAs QDs. The AFM results showed that the island size of the QDs is in the range of 20-40 nm with an average height of 5-16 nm and the highest island density of 1/spl times/10/sup 11//cm/sup 2/ has been achieved. Low temperature (5 K) photoluminescence (PL) wavelength of 1.10 /spl mu/m to 1.54 /spl mu/m was detected from these samples.

Characteristics of self-assembled GaInNAs/GaAsN quantum dot lasers grown by solid source molecular beam epitaxy

GalnNAs quantum dot lasers, grown using solid source molecular beam epitaxy, have been fabricated. The laser worked under continuous wave operation at room temperature. The lasers were also studied under pulsed operation with different temperature.

Room temperature cw lasing from GaInNAs quantum dots by solid source molecular beam epitaxy

We reported the growth and characterization of GaInNAs self-organized quantum dots grown by solid source molecular beam epitaxy equipped with RF nitrogen plasma source. High-density dots (/spl sim/10/sup 10/cm/sup 2/) are formed and dot size dependences on deposition amount and In composition in GaInNAs are observed by atomic force microscopy. Photoluminescence results show that increased deposition thickness caused larger dot height and then redshift of spectrum peak. Oxide-stripe laser with GaInNAs quantum dot active layer was fabricated and RT cw lasing at /spl sim/1.2 /spl mu/m is observed.

Photoluminescence behaviour of GaInNAs quantum wells annealed at high temperature

The photoluminescence (PL) characteristics of GaInNAs quantum wells (QWs) after high temperature post-growth annealing were studied. The QWs were grown using a radio frequency (RF) nitrogen plasma source in conjunction with a solid source molecular beam epitaxy (SSMBE) system. It is found that annealing at high temperature (840/spl deg/C) and long duration (10 min) results in significant improvement in the PL characteristics of the GaInNAs QWs. The PL intensity of the GaInNAs QW could improve by as much as 30 times after annealing, and its full-width-at-half-maximum (FWHM) reduces from 63.1 meV to a small value of 16.3 meV after annealing. There are two blueshift regions in the wavelength shift vs. nitrogen composition curve that shows the GaInNAs PL blueshift after annealing as a function of nitrogen composition. For as-grown GaInNAs QWs with a low nitrogen composition of less than /spl sim/1% (Region A), increasing indium composition from 22% to 30% during growth results in an increase of PL blueshift (after annealing) from 72 nm to 87 nm. On the other hand, for the as-grown GaInNAs QWs having higher nitrogen compositions of /spl sim/1% to /spl sim/3% (Region B), indium compositions (within the range of 19.5% and 25%) was found to have insignificant effect on the PL blueshift. In fact, the PL blueshift (as a result of annealing) increases rapidly from 72 nm to /spl sim/200 nm. The dominant mechanisms that give rise to the blueshift of the PL peak wavelength in GaInNAs QWs are proposed based on the PL, X-ray diffraction (XRD) and reflection high electron energy diffraction (RHEED) observations. The investigation has important implications for the growth of GaInNAs-based laser emitting at 1.31 /spl mu/m wavelength.

Ga(In)AsN growth by plasma-assisted molecular beam epitaxy towards 1.3 /spl mu/m and 1.55 /spl mu/m [lasers]

Ga(In)AsN is grown by molecular beam epitaxy using either a direct nitrogen beam or dispersive nitrogen radicals generated by a radio-frequency activated nitrogen source. The nitrogen incorporation shows a linear dependence on the RF power in a dispersive growth mode, contrasted to a saturated behavior in a direct growth mode. An additional indium flux causes a decrease in the nitrogen composition, an effect resulting from the increase in the growth rate. Quality Ga(In)AsN quantum wells were grown at 460/spl deg/C, with a photoluminescence emission close to 1.6 /spl mu/m. Also reported is a PL result amongst the best, as compared with the literature.