Correction of the Concentration Profile of the Epitaxially Grown GaAs Thin Film Layers, Measured by Electrolytic Capacitance-Voltage Method Antal Ürmös, Ákos Nemcsics Óbuda University, Institute of Microelectronics and Technology, Tavaszmező utca 17, H-1084, Budapest, Hungary E-mails: urmos.antal @ phd.uni-obuda.hu and nemcsics.akos@kvk.uni-obuda.hu Abstract— In this work we are dealing with the solution of a concentration profile measurement problem in the epitaxially grown III/V type compound semiconductor layers. The III/V based materials have specific electronic and optical properties, so they have large significance in the semiconductor device production. At these materials, the epitaxial growth is the fundamental technological step. During this epitaxial process is possible to change the doping concentration in the grown layer. In most cases, the electrolytic capacitance-voltage (ECV) technique serves for the measurement of this concentration profile. This method combines the conventional capacitance-voltage (CV) measurement with the anodic oxidation, to avoid the electrical break-down at the junction. The disadvantage of this method is that the contact surface increases during the measurement, because of the dissolution of the material. This surface growth - in certain layer structure - causes error in the measurement. In present work, we give a computational solution for this problem by our software, which we have developed in Matlab™. This algorithm calculates and summarizes the wall capacitance and subtract from the measured data, in each step. We demonstrate the operation of the program on different sample data series. I. INTRODUCTION The new applications of semiconductors (for instance microwave and optical communications) directed the researchers attention to the family of III/V compound semiconductors (e.g. GaAs, InP etc.). Many favorable properties (e.g.: direct band transition, higher charge carrier mobility) allows us to make such electronic devices, which we cannot prepare from silicon or we can produce only with lower parameters. In the technology of III/V-based compound semiconductors, the epitaxial growth is one of the most important step. Usually, in the silicon-based device technology, the differently doped layers are made by process of diffusion. This method is not applicable in case of compound semiconductors, because of thermal decomposition. During the epitaxial growth is possible to change the doping concentration of the growing layer, so a proposed concentration profile can be created. However not only the dopant, but the components of the semiconductors are also changeable. Hereby, the heterostructures of these materials can be produced by this method as well. In the different semiconductor technologies, the various qualifying measurements have very important role. These studies give us a chance to verify, for instance how we realized the required dopant distribution layer. For this goal, in most cases we apply the CV measurement. The disadvantage of this method is an electrical break-down of the junction, when the critical field intensity is reached. This effect can be avoided by ECV measurement, which essence is, that the semiconductor is contacted with an electrolyte, what is operated like a quasi-Schottky diode [1]. The layer removal is achieved by anodic dissolution of the semiconductor. Nevertheless there is another problem, because the wall capacitance of the etched range falsifies the measured results. In this article we are looking for the solution of this problem using our software, which we have developed in Matlab™. This algorithm calculates and summarizes the wall capacitance in each step and subtract from the measured data. We demonstrate the operation of the program on different sample data series. In this work, we show the simulation results on a dataset, which contains 8000 measured sample data. II. DESCRIPTION OF THE MEASURING TECHNIQUE Because of the technological feedback, we need to verify the epitaxially grown layer. One of the most important parameter is the concentration profile. By this property, we can satisfy, whether the realization of the required dopant distribution is successful or not. The most widely used method to measure the dopant distribution is the CV measurement, because the depth distribution of the free charge carriers is dependent from the capacitance, which is strongly related to dopant profile. Unfortunately, the measurement depth is limited, because of the electrical break-down of the junction, when the critical electrical field intensity is reached. At first - in order to try to avoid this phenomenon – the researchers etched the layer after the measurement, and measured the CV characteristics again. The problem of this method, that the measured results are hardly and inaccurately matched to each other and this work is time-consuming. In 1973, Ambridge and his colleagues suggested another method. The technique is that the semiconductor is contacted with an electrolyte, which operates as a quasi- Schottky diode. This examination method is the ECV measurement. Compared to other methods, there is an CINTI 2012 • 13th IEEE International Symposium on Computational Intelligence and Informatics • 20–22 November, 2012 • Budapest, Hungary 137 978-1-4673-5206-2/12/$31.00 ©2012 IEEE