Creating semiconducting nanostructures using the method of molecular beam epitaxy

Author: Gogita Papalashvili
Keywords: Semiconductor, Nanostructures, Molecular beam epitaxy
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The development of modern appliances in micro, nano and optoelectronics requires high quality semiconductor integral schemes. The most distinguished thing is to create heterostructure field effect transistor with two-dimensional electron gas (2DEG) on the compound of AIIIBV. These High-electron-mobility transistor (HEMT) are made with multilayer nanosized heterostructures, quantum wells, quantum dots. Two-dimensional electron gas is located in quantum well, which appears on the edge of heterojunction between narrow-bandgap and wide-bandgap of different semiconductors. The high value of electron mobility will be gained during the high concentration of electrons in 2DEG, which is crucial in creating high frequency transistors. To create nano size (10nm) heterostructure layers with sharp edges of junctions, has become possible by the development of molecular beam epitaxy (MBE). The main features of this method are: • The low speed of grow of the layer (0,1nm/s); • The low temperature of the substrate during the grow; • Low inertia, that gives us the ability to make heterojunctions with sharp border, also it makes it possible to dope different impurities to create layers of n or p type; • Ability to control and analyze the growing layers during the process. In MBE method the creation of thin layers is happening by condensation of the vapor of source molecules on the surface of substrate in the condition of high vacuum. The main goal of my work is determination of optimal technological parameters for MBE method to create heterostructure semiconductor GaAs/InGaAs/AlGaAs.