Michael H. Leary

High temperature continuous-wave operation of 1.3- and 1.55-/spl mu/m VCSELs with InP/air-gap DBRs

We demonstrate novel electrically pumped 1.3- and 1.55-/spl mu/m vertical cavity surface emitting lasers (VCSELs) with two InP/air-gap distributed Bragg reflectors (DBRs). The active regions comprise conventional InGaAsP multiple quantum wells. A tunnel junction is placed between the active region and the top DBR to convert electrons into holes, thus minimizing the use of p-type material in the structure to reduce the free-carrier loss and achieve current confinement. The whole structure was grown in a single growth run by low-pressure metal-organic chemical vapor deposition (MOCVD). For both 1.3and 1.55-/spl mu/m emission wavelengths, air-gap DBR VCSELs exhibit room-temperature continuous wavelength (CW) threshold current density as low as 1.1 kA/cm/sup 2/, differential quantum efficiency greater than 30%, and CW operation up to 85/spl deg/C. The single-mode output power was 1.6 mW from a 1.3 /spl mu/m VCSEL with a 6.3-/spl mu/m aperture and 1.1 mW from a 1.55 /spl mu/m VCSEL with a 5.7-/spl mu/m aperture under room temperature CW operation.

High temperature continuous-wave operation of 1.3-1.55 /spl mu/m VCSELs with InP/air-gap DBRs

High temperature CW operation of electrically pumped 1.3-1.55 /spl mu/m MQW VCSELs using top and bottom InP/air-gap DBRs with record low threshold current density is demonstrated.

Al Contamination in InGaAsN Quantum Wells Grown by Metalorganic Chemical Vapor Deposition and 1.3 µm InGaAsN Vertical Cavity Surface Emitting Lasers

We obtained high-quality InGaAsN quantum wells (QWs) by metalorganic chemical vapor deposition (MOCVD). Our InGaAsN QWs showed low threshold current densities and high-temperature characteristics (550 A/cm2, 150 K at 1275 nm for 3QWs) in broad-area lasers. High output power (2.8 mW at 1280 nm) was also obtained from the room-temperature continuous operation of InGaAsN 3QW vertical cavity surface emitting lasers. We revealed the first solid evidence that unexpected Al incorporation (Al contamination) occurred in InGaAsN QWs continuously grown on GaAs/AlGaAs structures by MOCVD. Our results suggest that Al contamination leads to a rough surface and low photoluminescence intensity of the InGaAsN QWs. By minimizing Al contamination, high-quality InGaAsN QWs were obtained. Al contamination in InGaAsN QWs should be carefully considered in the MOCVD growth of InGaAsN-based devices.

Low-resistance tunnel junctions on GaAs substrates using GaInNAs

Using molecular-beam epitaxy, we have fabricated p-n tunnel junctions lattice matched to GaAs substrates that consist of highly C-doped Ga0.93In0.07As on the p side, and highly Si-doped Ga0.93In0.07N0.02As0.98 on the n side. The introduction of N on the n side of the tunnel junction: (1) lowers the conduction band edge while leaving the valence band edge unchanged, (2) allows the introduction of In to further lower the band gap while remaining lattice matched to GaAs, and (3) increases the maximum Si donor activation that can be achieved. All three of these effects increase the tunneling probability for carriers across the junction and decrease the specific resistance. We estimate the active C acceptors on the p side to be 1.5×1020 cm−3 and the active Si donors on the n side to be 1.8×1019 cm−3. Because of the mutual passivation effect between N and Si atoms, the Si doping level was increased to 1.0×1020 cm−3 to achieve this active net donor concentration. The specific resistance of test tunnel junctions ...

MOCVD growth of InGaAsN QWs and 1.3 /spl mu/m VCSELs

This paper demonstrates MOCVD growth of InGaAsN quantum wells and fabrication of vertical cavity surface emitting lasers (VCSELs). Results on the modulation and high temperature characteristics of 1.3 /spl mu/m-range InGaAsN vertical cavity surface emitting lasers (VCSELs) are also presented. Over 1 mW of single-mode output power is obtained at 80/spl deg/C. Clear eye opening at 2.5 Gb/s and 10 Gb/s are obtained up to 120/spl deg/C and 90/spl deg/C, respectively.

Long-wavelength VCSELs with InP/air-gap DBRs

We demonstrate novel electrically pumped 1300 nm and 1550 nm VCSELs with two InP/air-gap DBRs. The active regions comprise conventional InGaAsP multiple quantum wells. A tunnel junction is placed between the active region and top DBR to convert electrons into holes, thus minimizing the use of p-type material in the structure to reduce the free-carrier loss and achieve current confinement. The whole structure was grown in a single growth run by low pressure MOCVD. For both 1300 and 1550 nm emission wavelengths, air-gap DBR VCSELs exhibit roomtemperature, CW threshold current density as low as 1.1 kA/cm2, differential quantum efficiency greater than 30%, and CW operation up to 85°C. The single-mode output power was 1.6 mW from a 1300 nm VCSEL with a 6.3 μm aperture; and 1.1 mW from a 1550 nm VCSEL with a 5.7 μm aperture under room temperature CW operation

Al Gettering for InGaAsN in Metalorganic Chemical Vapor Deposition

We proposed and demonstrated an Al gettering process for high-quality InGaAsN quantum wells grown by metalorganic chemical vapor deposition. Ammonia flow prior to InGaAsN growth eliminates undesirable Al incorporation in the InGaAsN continuously grown on GaAs/AlGaAs layers. The InGaAsN quantum well without Al contamination showed a smooth surface and strong photoluminescence intensity. An InGaAsN vertical cavity surface-emitting laser structure grown in a single-step process using the Al gettering process showed continuous-wave operations with 2.7 mW of 1279 nm emission at room temperature.

Electrically pumped 1.3 /spl mu/m VCSELs with InP/air-gap DBRs

We demonstrate novel electrically pumped 1.3 p VCSELs with two InP/air-gap DBRs. The devices exhibit threshold current density as low as 1.3 kA/cm2 at room temperature with CW excitation, and lase up to 80°C.