New current injection 1.5-μm wavelength GaxAlyIn1−x−yAs/InP double-heterostructure laser grown by molecular beam epitaxy

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Abstract
We have prepared and characterized for the first time a new current injection double‐heterostructure (DH) laser with GaxAlyIn1−x−y As as the active layer and InP as the cladding layers operating at 1.5‐μm wavelength. In this new heterostructure, there is only one group V element involved in every layer. This eases the precise control of lattice matching during molecular beam epitaxial (MBE) growth. At the same time, it eliminates the use of Al0.48In0.52 As, which is of lower quality than InP when grown by MBE, as the cladding layers. Broad‐area Fabry–Perot diodes of 380×200 μm have a threshold current density of ∼3.2 kA/cm2 for active layer thickness of 0.25 μm. In the temperature range ∼15–50 °C, the threshold temperature dependence coefficient T0 is typically ∼40 K. Above ∼50 °C, T0 decreases to ∼25–35 K. The present laser also represents the first current injection DH laser emitting at 1.5 μm ever prepared by MBE. In the present experiment, As2 instead of As4 was also used for the first time in growing the GaxAlyIn1−x−y As layers by MBE in order to improve their quality. This becomes particularly important as the substrate growth temperatures employed are relatively low, ≲625 °C.