Control of the interface roughness in highly strained InxGa1-xAs/In0.52Al0.48As heterostructures

InGaAs/InAlAs heterostructures lattice mismatched to InP have emerged as an important system for microoptoelectronic applications, thanks to the large band gap of InAlAs and the high conduction band discontinuity at the interface. Moreover, a high carrier confinement and a small effective mass of the electrons in the InGaAs layer make this system very suitable for high speed devices. However, to achieve the theoretical performances of the devices, high quality layers and abrupt interfaces are required. The interface roughness can be very sensitive to the growth conditions. This is specially true for molecular beam epitaxy (MBE) growth of compressively strained In-rich In_xGa _1-xAs layers. Such layers may develop some surface roughness followed by the appearance of three dimensional (3D) islands when the epilayer thickness and the strain increase. In this work we show that structural properties of quantum well interfaces can be characterized by photoluminescence (PL) spectroscopy, leading to important informations about the surface roughness and the growth mode