XPS study of InP/InGaAs/InGaAsP microstructures irradiated with ArF laser in air and deionized water Neng Liu 1 , Khalid Moumanis 1 , Sonia Blais 2 , Jan J. Dubowski 1 * 1 Laboratory for Quantum Semiconductors and Photon-based BioNanotechnology, Department of Electrical and Computer Engineering, Université de Sherbrooke, Québec, Canada J1K 2R1 2 Centre de caractérisation des matériaux, Université de Sherbrooke, Québec, Canada J1K 2R1 *URL: http://www.dubowski.ca ABSTRACT Excimer lasers, due to their compatibility with a large-scale industrial production, are attractive tools for precise processing of photonic and microelectronic materials. In this article, we discuss the effect of ArF excimer laser defect formation on the surface of InP/InGaAs/InGaAsP quantum well (QW) microstructures irradiated in air and deionized (DI) water environments. Structural defects on surfaces of such QW materials have been known to induce vacancy diffusion towards the QW region and lead to the so called quantum well intermixing (QWI) effect during the rapid thermal annealing step. Excimer lasers have been used to create surface defects on InP/InGaAs/InGaAsP microstructure and induce QWI during high temperature annealing. Chemical composition of the QW microstructures irradiated with ArF laser in air and DI water is studied with X-ray photoelectron spectroscopy to investigate both the formation and role of the surface defects in the laser-induced QWI process. Keywords: InP/InGaAs/InGaAsP quantum well microstructures, ArF excimer laser radiation, quantum well intermixing, X-ray photoelectron spectroscopy 1. INTRODUCTION InP based quantum well (QW) microstructures, such as InP/InGaAs/InGaAsP, are important materials for photonic devices operating in the near-infrared region of an electromagnetic spectrum. A semiconductor wafer with as-grown QW microstructure, typically, represents same-bandgap material. Functioning of active photonic devices, such as arrays of multi-color lasers and modulators, however, requires different bandgap materials. The most frequently used approach allowing fabrication of multi-bandgap wafers is based on an epitaxial growth/re-growth technique, although the fabrication of such wafers at an attractive cost has remained a challenging task. Post-growth processing that employs so- called quantum well intermixing (QWI) has been investigated to address this issue. 1, 2 Defect-driven QWI has remained a challenging task, mainly due to the difficulties in controlling the nature, concentration and location of defects induced by ion implantation 3 , impurity doping 4 or dielectric layer (SiO 2 /Si 3 N 4 ) coating. 5 The application of excimers for that purpose brings advantages related to the strong optical absorption of these lasers, e.g., ArF at 193 nm, KrF at 248 nm and XeCl at 308 nm, in InP and GaAs – materials that have been employed for capping most of the III-V QW microstructures. For instance, the strong absorption of InP, reaching about 10 6 cm -1 the UV spectral region 6 , allows creating defects confined to the near surface, typically less than 10 nm deep. Excimer lasers have already been applied in manufacturing processes of semiconductor devices 7 , thus they are suitable for a relatively large-scale production. An early study of excimer lasers used for selected area defect formation have revealed feasibility of this approach for QWI and selected-area bandgap engineering. 8, 9,10 The full quantitative description of the process, however, has been missing. The progress in that context is important as the properties of future photonic devices, made from the laser processed material, are expected to depend on the nature of laser-induced defects and microstructural properties of laser modified surface, similarly, e.g., to the dependence of the performance of metal-semiconductor contacts on the properties of semiconductor surfaces. 11 Irradiation of InP surface with an ArF laser (Ȝ=193 nm) in an air environment leads to the increase, in proportion to the number of laser pulses, of both the indium (In)/phosphorus (P) atomic ratio and thickness of the laser induced oxide layer. 9 This results in an increased concentration of P vacancies and In interstitials that will diffuse towards the QW Synthesis and Photonics of Nanoscale Materials IX, edited by Frank Träger, Jan J. Dubowski, David B. Geohegan, Proc. of SPIE Vol. 8245, 82450E · © 2012 SPIE · CCC code: 0277-786X/12/$18 · doi: 10.1117/12.913082 Proc. of SPIE Vol. 8245 82450E-1 Downloaded from SPIE Digital Library on 07 Jun 2012 to 132.210.72.142. Terms of Use: http://spiedl.org/terms