Intermixing diffusion coefficients and residual damage in InGaAs/InP heterostructures of varying composition and strain

Abstract

Quantum Well Intermixing (QWI) methods applied to InGaAsP/InP Quantum Well (QW) structures are the subjects of intense research efforts in view of their potential for low-cost fabrication of photonic integrated circuits in the telecommunication wavelength ranges of 1.3-1.6 mu m. In this work, two methods of QWI are investigated: ion implantation QWI and grow-in-defect QWI. Both methods aim at the use of area selective creation of defects in the sample to promote material interdiffusion during a rapid thermal annealing (RTA) process. The applicability of each QWI methods is investigated and it depend on two main factors: 1. Our ability to predict the shifts obtained given controlled experimental conditions for a wide class of materials. 2. The optical quality of the layer after QWI. In the first part of the work, absorption measurements are compared with QWI simulations to quantify the relative interdiffusion length of group-V and group-III atoms (k =deltaV/deltaIII). Values of k = 4 are obtained for lattice-matched (LM) and tensile strain QW intermixed with grown-in-defect QWI, while a value of k = infinity is found for a LM QW sample intermixed via ion implantation QWI. This information is important to establish predictive models of bandgap shifts. In the second part of the work, carrier lifetimes in as-grown and intermixed samples are measured at varying temperatures. Lifetimes measured in intermixed samples are found to be more sensitive to changes in temperature, suggesting the presence of non-radiative defects