Chia-Pin Sung

1.3-/spl mu/m InAs-InGaAs quantum-dot vertical-cavity surface-emitting laser with fully doped DBRs grown by MBE

We report InAs-InGaAs quantum-dot vertical-cavity surface-emitting lasers (VCSELs) grown by molecular beam epitaxy with fully doped n- and p-doped AlGaAs distributed Bragg reflectors and including an AlAs layer to form a current and waveguiding aperture. The metal contacts are deposited on a topmost p/sup +/-GaAs contact layer and on the bottom surface of the n/sup +/-GaAs substrate. This conventional selectively oxidized top-emitting device configuration avoids the added complexity of fabricating intracavity or coplanar ohmic contacts. The VCSELs operate continuous-wave at room temperature with peak output powers of 0.33 mW and differential slope efficiencies up to 0.23 W/A. The peak lasing wavelengths are near 1.275 /spl mu/m, with a sidemode suppression ratio of 28 dB.

Characteristics of MOCVD- and MBE-grown InGa(N)As VCSELs

We report our results on InGaNAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) in the 1.3 ?m range. The epitaxial structures were grown on (1?0?0) GaAs substrates by metalorganic chemical vapour deposition (MOCVD) or molecular beam epitaxy (MBE). The nitrogen composition of the InGa(N)As/GaAs quantum-well (QW) active region is 0?0.02. The long-wavelength (up to 1.3 ?m) room-temperature continuous-wave (RT CW) lasing operation was achieved for MBE- and MOCVD-grown VCSELs. For MOCVD-grown devices with n- and p-doped distributed Bragg reflectors (DBRs), a maximum optical output power of 0.74 mW was measured for In0.36Ga0.64N0.006As0.994/GaAs VCSELs. A very low Jth of 2.55 kA cm?2 was obtained for the InGaNAs/GaAs VCSELs. The MBE-grown devices were made with an intracavity structure. Top-emitting multi-mode 1.3 ?m In0.35Ga0.65N0.02As0.98/GaAs VCSELs with 1 mW output power have been achieved under RT CW operation. A Jth of 1.52 kA cm?2 has been obtained for the MBE-grown In0.35Ga0.65N0.02As0.98/GaAs VCSELs, which is the lowest threshold current density reported. The emission characteristics of the InGaNAs/GaAs VCSELs were measured and analysed.

Mode Control of Vertical-Cavity Surface-Emitting Lasers by Germanium Coating

We have successfully developed a selective surface coating technique to control the modal behavior of the ion-implanted vertical-cavity surface-emitting laser (VCSEL). With selective deposition of a germanium coating by the lift-off process, we could spatially control the threshold gain condition of the VCSEL to support the single transverse mode. The threshold current is 7 mA and single transverse mode operation is maintained up to 1 mW. The method is simple and nondestructive compared with other techniques.

Improvement of high-speed oxide-confined vertical-cavity surface-emitting lasers

High-speed vertical-cavity surface-emitting lasers that could be modulated up to 10 Giga-bit-per-second (Gbps) were accomplished by using additional proton implantation to reduce the parasitic capacitance. The eye diagram of the implanted device shows a noticeable improvement when compared with those devices without implantation. In contrast to previous reports, moreover, the output power-current-voltage (L-I-V) characteristics of the fabricated devices in this study show excellent consistency between before and after implantation. The high-temperature lifetime of devices fabricated with a similar process has already exceeded 8100 h up to the present day.

Low-Threshold-Current-Density, Long-Wavelength, Highly Strained InGaAs Laser Grown by Metalorganic Chemical Vapor Deposition

A long-emission-wavelength laser with multiple InGaAs/GaAs quantum wells without a strain-compensated barrier was grown by metalorganic chemical vapor deposition (MOCVD). InGaAs quantum well (QW) broad-area laser diodes with an emission wavelength of up to 1214 nm were realized. A measured room-temperature threshold current density of only 173 A/cm2 for a 2-mm-cavity device and a transparency current density of 66 A/cm2 were obtained. The internal quantum efficiency and laser cavity loss were 67% and 6 cm-1, respectively.

A new process to improve the performance of 850 nm wavelength GaAs VCSELs

Abstract In this article, we propose a new process method to improve the light output power of GaAs vertical-cavity surface-emitting lasers (VCSELs). The VCSELs with filling Al metal into the ring trench will exhibit a higher quantum efficiency and have a light output power of 1.45 times higher than those without filling Al. In addition, the trench filled with Al metal can benefit in the bonding process and behavior as a mirror to reduce the output power loss. These VCSELs show good output characteristics and high-temperature operation.

Characteristics of InGa(N)As VCSELs for fiber optic applications

We report our results on InGaNAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) for fiber-optic applications in the 1.3 μm range. The epitaxial structures were grown on (100) GaAs substrates by MBE or MOCVD. The nitrogen composition of the InGaNAs/GaAs quantum-well (QW) active region is 0 to 0.02. Long-wavelength (up to 1.3 μm) room-temperature continuous-wave (RT CW) lasing operation was achieved for MBE and MOCVD-grown VCELs. For MOCVD-grown devices with n- and p-doped distributed Bragg reflectors (DBRs), a maximum optical output power of 0.74 mW was measured for In0.36Ga0.64N0.006As0.994/GaAs VCSELs. The MBE-grown devices were made with intracavity structure. Top-emitting multi-mode 1.3 μm In0.35Ga0.65N0.02As0.98/GaAs VCSELs with 1mW output power have been achieved under RT CW operation. Emission characteristics of InGaNAs/GaAs VCSELs were measured and analyzed.

Effect of electrostatic discharge on power output and reliability of 850 nm vertical-cavity surface-emitting lasers

In this article, we investigate the influence of electrostatic discharge (ESD) stress voltage on the device performance of 850 nm vertical-cavity surface-emitting lasers (VCSELs). The ESD effect induces dark-region defects, which act as nonradiative recombination centers in the active layer and increase the leakage current and degrade the light output power. Without ESD stress voltage, the VCSELs exhibit multiple transverse mode. However, the devices exhibit a weak but single fundamental mode with smaller beam divergence by increasing the stress voltage up to 2.6 kV. In addition, the VCSELs have serious degradation in light output power and a lifetime of less than 5 h at stress voltage beyond the ESD threshold voltage of 1.2 kV.

The effect of indium tin oxide as an ohmic contact for the 850 nm GaAs oxide-confined VCSELs

Abstract In this article, we report the effect of indium tin oxide (ITO) as a p-type ohmic contact for the 850 nm GaAs oxide-confined vertical-cavity surface-emitting lasers (VCSELs). The VCSELs with ITO contact have a threshold current of 0.96 mA, a full-width-at-half-maximum angle of beam divergence of 27° and an ellipticity of 103.8% for the far-field pattern at a 10-mA driving current, which are the same as those of the conventional VCSELs with Au/Zn/Au or Ti/Pt/Au ohmic contacts. In addition, the VCSELs with ITO contact exhibit a light output power of 1.27 times in magnitude higher than those of the conventional VCSELs.

Effect of Annealing on Low-Threshold-Current Large-Wavelength InGaAs Quantum Well Vertical-Cavity Laser

An emission wavelength record emission wavelength of 1245 nm in double InGaAs/GaAs quantum wells without a strain-compensated barrier is obtained by metalorganic chemical vapor deposition (MOCVD). The effect of annealing on highly strained InGaAs quantum wells is analyzed using phtoluminanescence spectra. By comparing devices p-type distributed Bragg reflector (p-DBR) growth temperatures, the preliminary results indicate that a device with a low p-DBR growth temperature of 670°C exhibits a low threshold current and a high light output power. A threshold current of 6.7 mA in an InGaAs vertical-cavity surface emitting laser (VCSEL) in CW operation is realized with an emission spectrum up to 1.26 µm.