W. T. Tsang

Molecular beam epitaxial growth of high‐purity AlGaAs

We report molecular beam epitaxial (MBE) growth of AlGaAs in the previously unexplored temperature range exceeding 800u2009°C for which excellent material can be achieved. Photoluminescence reveals bound excitonic linewidth as sharp as 3.6 meV, which is among the narrowest ever reported for material of equivalent Al mole fraction. In this temperature range carbon impurity concentrations are found to be dramatically reduced while temperature‐dependent data provide information from which an understanding of carbon incorporation during MBE growth emerges.

High-reliability 1.3-/spl mu/m InP-based uncooled lasers in nonhermetic packages

We report the first uncooled nonhermetic 1.3-/spl mu/m InP-based communication lasers that have reliability comparable to their hermetically packaged counterparts for possible applications in fiber in the loop and cable TV. The development of reliable nonhermetic semiconductor lasers would not only lead to the elimination of the costs specifically associated with hermetic packaging but also lead the way for possible revolutionary low-cost optoelectronic packaging technologies. We have used Fabry-Perot capped mesa buried-heterostructure (CMBH) uncooled lasers with both bulk and MQW active regions grown on n-type InP substrates by VPE and MOCVD. We find that the proper dielectric facet passivation is the key to obtain high reliability in a nonhermetic environment. The passivation protects the laser from the ambient and maintains the proper facet reflectivity to achieve desired laser characteristics. The SiO facet passivation formed by molecular beam deposition (MBD) has resulted in lasers with lifetimes well in excess of the reliability goal of 3,000 hours of operation at 85/spl deg/C/90% RH/30 mA aging condition. Based on extrapolations derived experimentally, we calculate a 15-year-average device hazard rate of <300 FITs (as against the desired 1,500 FITs) for the combination of thermal-and humidity-induced degradation at an ambient condition of 45/spl deg/C/50% RH. For comparison, the average hazard rate at 45/spl deg/C and 15 years of service is approximately 250 FITs for hermetic lasers of similar construction. A comparison of the thermal-only degradation (hermetic) to the thermal plus humidity-induced degradation (nonhermetic) indicates that the reliability of these nonhermetic lasers is controlled by thermal degradation only and not by moisture-induced degradation. In addition to device passivation for a nonhermetic environment, MBD-SiO maintains the optical, electrical, and mechanical properties needed for high-performance laser systems.

1.3 μm InGaAsP/InP multiquantum well buried heterostructure lasers grown by chemical‐beam epitaxy

High performance InGaAsP/InP multiquantum well (MQW) buried heterostructure lasers emitting around 1.3 μm were prepared for the first time by chemical‐beam epitaxy. At 20u2009°C, continuous‐wave (cw) threshold currents were 5–8 mA and quantum efficiencies were 0.35–0.45 mW/mA for 250 μm long lasers having one facet ∼85% reflective coated. At 80u2009°C, the cw threshold currents remained low, 23 mA, quantum efficiency stayed high, 0.22 mW/mA, and output power of ∼10 mW was achieved. cw power output as high as 125 mW was achieved with 750 μm long lasers having AR–HR (∼5%–85%) coatings. Lasers with bulk active were also studied for comparison. Though they also have excellent device performance, in general, they are somewhat inferior to MQW lasers.