Electrical modelling of ohmic contacts formation on metal-n-GaAs systems

Abstract

The contaet resistance and quality can be determined by various methods. A common disadvantage of these methods is to investigate the contact after its formation occasionally by meaus of a special measuring sample. In the present work a new method for the in situ investigation of the metal--semiconductor contact is proposed. This method was used for the control of the teehnology of the metal--semiconductor ohmic contacts for high power Gunn diodes. A numerical analysis for the GaAs-AuGeeu t system was ,nade based on the electrical modelling of the eontact formation. ]. IntroductionThe investigation of metal--semiconductor eontaets is a very important task from both the practical and theoretical point of view. The modern, often eompound-semiconductor based, semiconductor devices operating with high eurrent densities raise new demands for both the properties of contaet and contacting technology.One important feature of contacts is their resistivity, and for its measurement several methods have been designed to match the given basic material, layer structure (bulk crystal of a multi-layer epitaxial structure on eondueting of semi-insulating substrate) and measurement aecuracy.Contact assessing methods usabIe in technologieal research should comply with the following requirements:1. It is to be carried out on the device of specimen to be measured, i.e. no separate test piece should be needed.2. Its realization should be simple and rapid. 3. The accuracy of measurement should be high. 4. Measurement data should permit to draw conclusions on the effeet of factors influencing coutact properties. The determination of contaet resistance eonaists, in fact, in separating the resistance of the bulk (which may be of homogeneous of layered structure) and contact resistance from the total resistanee measured.

Mass spectrometric study of semiconductor layer structures

“…According to the method described in [4] a low measuring current was applied to the specimen and the potential drop was recorded during the annealing. This vohage is proportional to the momentary resistance of the sample in the 20--200 ~ temperature range as it was shown in [5]. Some characteristic R(T) and Y(T) curves are presented in the Figures.…”