Preparation and Chemical Functionalization of InAs/GaAs Quantum Dot Structures

Back in the seventies, only a few years after the invention of low-loss optical sensors, it became apparent that optical devices can not only reliably transmit data, but also provide remarkable sensing capabilities. These sensing capabilities combined with unique properties, such as total dielectric design, complete immunity to electromagnetic interference, small size, capability for distributed sensing, safety and good bio-compatibility attracted significant attention in both industry and academia. The rapid development of sensors based on semiconductor materials over the past two decades has been brought about in part by the application of integrated circuit technologies to fabricating precision micro-structures and devices, and by the great need for sensors that can provide the necessary performance requirements that many of today's electronic systems demand. Currently molecular sensing is being represented by traditional semiconductors (p-type, n-type), where the area/volume proportions of the material have determined values. Those values influence the structure stability, the absorption and the emission properties of the sensor device. In this communication we present our preliminary results on the preparation and characterization (AFM and XPS) of InAs Quantum Dot deposited on GaAs substrates1 and on their superficial functionalization with synthetic molecular receptors belonging to the class of calixarenes.2 The well-known recognition properties of the latter compounds together with the photosensing abilities of the InAs/GaAs QDs may indeed lead to the development of potential chemosensors (see Figure 1) which offer a better integration in the sensor circuit and an improvement of sensing properties. These novel devices will bring highly desirable properties such as: high structure stability, large area/volume proportion and an emission in a range of 1-5 ?m which is ideal for fibre optics transmission of information in the sensing.