Evidence of Quantum Confined Stark Effect Due to Doping Profile in InAsP/InP Quantum Well Structures and its Modification by Ion Bombardment

We investigate the effects of the doping profile on the photo-luminescence (PL) and cathodo-luminescence (CL) of InAsP/InP quantum well (QW) structures grown on InP. A strong difference between the PL and CL of undoped and doped samples is observed. This is attributed to the quantum confined Stark effect (QSCE) and to the escape of photo-generated charge carriers out of the QWs by tunneling. These effects were probed by measuring the CL on biased samples. In addition, by exposing the samples to the ion flux in a plasma etching reactor (with a gas mixture containing chlorine), we observed for the doped sample a very strong change of the spectral shape of the PL. This change is discussed assuming that some ions penetrate the QW structure, thus compensating the initial electric field due to the doping profile.