Strained InAsN/InGaAs/InP multiple quantum well structures grown by RF-plasma assisted GSMBE for mid-infrared lasers applications

The authors report the growth, structural and optical characteristics of strained 10-period InAs1-x/Nx/Ga0.47As multiple quantum well (MQW) structures on InP substrates grown by gas-source molecular beam epitaxy. Atomic nitrogen was generated using a RF-plasma cell. Double crystal X-ray diffractometer (DXRD) measurements indicated that adding N to the InAs layer reduced the net compressive strain of the MQW. The highest nitrogen composition obtained in this study was 19.5%. It was also found that the incorporation of nitrogen resulted in red-shifted photoluminescence (PL) emission energy of the QWs. However, increased nitrogen composition broadened the DXRD linewidth and degraded PL intensity. The very broad PL linewidth might be related to alloy inhomogeneity. Finally, ridge waveguide lasers with different periods (n = 2 - 8) of InAs0.97N0.03/InGaAs QWs as the gain medium were fabricated. A device with four QWs gave the best performance and demonstrated pulsed oscillation up to 260K at an emission wavelength of 2.38 μm with a threshold current density of 3.6 kA/cm2. This indicates the potential of InAsN as a material for mid-infrared applications.