The dissertation for the candidate of technical sciences degree (comparable to the Academic Degree of Doctor of Philosophy) on specialty 05.27.06 - Technology, equipment and production of electronic technique. - Engineering Institute of Zaporizhzhya National University, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, 2019.
The dissertation is devoted to the development of a technology for reproducible manufacturing ohmic and injection barrier transitions based on the silver to gallium arsenide of n-type conductivity.
The influence of various factors on the quality of ohmic and injection barrier transitions to gallium arsenide is analyzed. It is established that the physical model of the real metal-semiconductor contact (MSC) is more complicated comparing to the ideal MSC models. A model, which describes the transport processes between metal electrons, boundary states, and free semiconductor carriers has got further developed. This model can take into account any physical mechanism of charge transfer in the metal-semiconductor structure by appropriate selection of kinetic coefficients in transfer processes.
It is shown that the existing silver-arsenide gallium ohmic and injection barrier transitions producing technologies have a number of disadvantages, including the contact parameters reproducibility lack. The investigation of the metal deposition conditions and heat treatment regimes influence on the electrophysical parameters of metal-GaAs silver-containing contacts is highlighted in an independent scientific problem whose solution can lead to a significant representations refinement of processes in metal-GaAs contacts and will allow to improve the technical characteristics and parameters of microwave GaAs devices with the Schottky barriers in particular, devices with inter-valued electronic transitions (IET-devices). Thus, the study of patterns, the development and optimization of technological regimes for the reproducible manufacturing silver-GaAs based ohmic and injection barrier transitions with optimal performance and quality characteristics for microwave devices is an important and actual problem.
The complex technological and electrophysical research of single- and multi-component metal contact systems based on the silver to n-n+GaAs have been made.
It was experimentally established that the qualitative characteristics of ohmic and injection barrier transitions depend heavily on the temperature of the substrate and the contact structure heat treatment regimes. The patterns of the specific transient resistance dependence from the temperature regimes for the creation of ohmic contacts Ag-Ge-In/n-n+GaAs are established, which leads to the the specific transient resistance reducing to the minimum value, which is for an order smaller comparing to known analogues. It has been shown that the quality of the ohmic contact is improved if the GaAs substrate hold in dioxiacaric acid after the chemical treatment in the sulfuric acid and further anneal it in vacuum.
The technology for the production of Ag/n-n+GaAs injecting barrier transitions are improved and optimized. It takes into account the barrier transitions forming patterns in different temperature regimes. The optimal regimes for the Schottky barrier height increasing up to 0,98 V are determined. It is established that the real current-voltage characteristics of the metal-semiconductor barrier transitions depend on their manufacturing technology. But the accuracy of the basic barrier transitions qualitative parameters (the φB barrier height and the nonideality η factor) depends not only on the accuracy of the measurement of current and voltage, but also on the method of their determination.
The Schottky barrier height determination methods based on the current-voltage characteristics using as example the Ag/n-n+GaAs barrier transitions, produced under different heat treatment regimes, are analyzed and tested. With a small extension of the exponential part of the CVC, a direct approximation method is recommended for determining the potential barrier height.
A simplified mathematical model of the IET-device with Schottky barriers is proposed. It can be used to calculate the parameters of complicated multifunctional IET-devices with several controlling electrodes. On the basis of this model, a multi-electrode IET-device with expanded functionality has been developed. This device is capable in certain modes to perform functions of a Schottky diod, an runway wave transistor or a microwave generator, which will allow to obtain a technical and economical effect by the cost reducing for developing of a number devices for the microwave range.
Key words: GaAs, ohmic and injection barrier transitions, injection rate, silver, triple alloys, IET-devices
