Yoshihiko Ikenaga

1.4 µm GaInNAs/GaAs Quantum Well Laser Grown by Chemical Beam Epitaxy

We have achieved room-temperature pulsed operation of 1.4-µm-wavelength GaInNAs/GaAs double quantum well (DQW) lasers with increased nitrogen composition up to 1.7% grown by chemical beam epitaxy (CBE). A threshold current density of 8.9 kA/cm2 was obtained, and the characteristic temperature (T0) from 10 to 40°C was 94 K.

Nitrogen Composition and Growth Temperature Dependence of Growth Characteristics for Self-Assembled GaInNAs/GaAs Quantum Dots by Chemical Beam Epitaxy

A GaInNAs/GaAs quantum dot (QD) system is anticipated as a novel material to extend the emission wavelength of GaAs-based lasers. We have studied GaInNAs QDs by chemical beam epitaxy (CBE). The growth temperature and nitrogen composition dependence on the size and density of GaInNAs QDs were investigated. The growth characteristics of GaInNAs QDs were quite different from those of GaInAs QDs. It was found that the GaInNAs QDs showed a small change in size and the density through the temperature range from 500°C to 540°C, although the size increased and the density decreased for GaInAs QDs with increasing growth temperature. The density of about 9×1010 cm-2 was obtained for GaInNAs QDs at 540°C. This value is three times larger than that of GaInAs QDs grown at 530°C. These results indicate a marked change in the migration length of adatoms due to the nitrogen introduction. The nitrogen introduction effect on QD formation may be advantageous for improving the gain characteristics of long-wavelength QD lasers.

Composition Dependence of Thermal Annealing Effect on 1.3 µm GaInNAs/GaAs Quantum Well Lasers Grown by Chemical Beam Epitaxy

The thermal annealing process is effective to improve the optical quality of GaInNAs/GaAs quantum wells (QWs). However, a blue shift of the emission peak wavelength occurs during the annealing and it is strongly related to the annealing condition and the composition of GaInNAs/GaAs QWs. In this study, we investigated the dependences of both the annealing condition and the composition on the lasing characteristics of 1.3 µm GaInNAs/GaAs QW lasers.

1.3 /spl mu/m-GaInNAsSb based material and its application to VCSELs

1.3 /spl mu/m-range GaInNAsSb material and its application to VCSELs were investigated. GaInNAsSb active layer that include the small amount of Sb can be easily grown in 2 dimensional manner as compared with GaInNAs due to the suppression of the formation of 3-dimensional growth in MBE growth. We obtained the lowest Jth per well (150A/cm/sup 2//well) as for the edge-emission type lasers due to the high quality of GaInNAsSb-QW. Using this material for the active media, we accomplished the first CW operation of 1.3 /spl mu/m-range GaInNAsSb VCSELs.

CBE growth of GaInNAs quantum wells and dots for long-wavelength lasers

The GaInNAs is an attractive material for long wavelength lasers on a GaAs substrate and the GaInNAs vertical cavity surface emitting laser (VCSEL) is a viable candidate for low cost and high performance lasers of 1.3micrometers wavelength networks due to excellent temperature characteristics and manufacturing capability of VCSELs. We have successfully grown GaInNAs quantum wells by chemical beam epitaxy and investigated the growth condition toward better crystal quality by employing a radical nitrogen source and thermla annealing. Lasing characteristics of CBE grown 1.2 micrometers GaInNAs lasers are a threshold current density of less than 1kA/cm2, and high temperature operation up to 170 degrees C with an excellent slope efficiency change below -0.004dB/K. A characteristic temperature of 270K is also demonstrated. GaInNAs quantum dots were also investigated for the further progress of GaInNAs lasers. The growth of self-organized Qds and a lasing operation at 77K was demonstrated.

Growth temperature and nitrogen composition dependence of growth characteristics of GaInNAs/GaAs quantum dots by chemical beam epitaxy

The self-assembled In(Ga)As quantum dot (QD) laser have been realized for the long wavelength emission and improvement of laser characteristics. However, In(Ga)As QD lasers still have some problems, such as an increase of threshold at high temperature, and low gain. These problems are due to difficulty in control of the size and the density, which are related to the wavelength and the threshold. The GaInNAs system has been developed as the QW for elongating the emission wavelength. The introduction of the nitrogen (N) into In(Ga)As QDs is an attractive choice because of the possibility of independent control of the wavelength and dot density. In this study, we have investigated the growth characteristics of GaInNAs QDs by CBE in detail.

Formation of GaInNAs/GaAs densely packed quantum dots by chemical beam epitaxy

The GaInNAs/GaAs quantum dot (QD) system is expected to extend the emission wavelength of GaAs-based lasers. We successfully formed GaInNAs QDs by chemical beam epitaxy (CBE). The growth temperature dependence of the size and density of GaInNAs QDs was quite different from GaInAs QDs. It was found that the size of GaInAs QDs increased and density decreased with increasing growth temperature from 500/spl deg/C to 540/spl deg/C. On the other hand, GaInNAs QDs showed a small change of size and density. A density of about 9/spl times/10/sup 10/ cm/sup -2/ was obtained for GaInNAs QDs at 540/spl deg/C which is three times larger than that of GaInAs QDs. Thus, nitrogen introduction into the QDs provides a novel control technique of dot size and density.