Mechanism of Forming of Quantum-Size Layers of AlGaN/GaN/InGaN/GaN Layers
The electro-physical properties of silicon limit its application for optoelectronic elements and for microwave technology devices. In this case silicon is replaced by the material with higher band gap. These materials include the nitrides of the III-group elements, in particular, GaN, AlN, InN and solid solutions based on them. As a result, it becomes possible to manufacture devices with the high efficiency, for example, the light diodes and photoreceivers, capable to operate in a very broad radiation spectrum. Besides, the materials based on GaN are successfully used for creation of powerful microwave devices, such as the transistors with high electron mobility (YEMT) operating at high temperatures. Some technological features of formation of the active layers in heterostructures of AlGaN/GaN/InGaN/GaN MOS using the metal organic compounds have been considered. As the initial substances the high-purity ammonia (NH3) and organometallic compounds of gallium, aluminum and indium (MOC Ga, MOC A1 and Mosp) in trimethylene form have been used. The temperature dependence of the growth rate has been investigated in a wide temperature range, which has shown the critical role of the absorption processes on the surface of the growth. To simulate the process and to determine the conditions of forming the composition of solid solutions based on GaN the thermodynamic analysis of patterns in the implementation of the process under study has been performed. It has been found that while obtaining solid solutions in the high temperature range the InN content in them exceeds 0.4 mole frac. and while reducing the growth temperature to 600 °C the conditions of In occurrence in the solid solution are significantly improved and the concentration increases up to 0.9 mole.frac. It has been shown that while growing the GaAlN solid solutions in the wide temperature range it is possible to obtain solid solutions with AlN content from 0.1 to 0.9 mole frac. The experimental studies have confirmed the calculations. Therefore, when growing layers of Ga1-xInxN quantum wells in the active region of heterostructures for industrial chips of blue LEDs with the indium content x = 0.1 - 0.15 it is necessary to reduce the growth temperature. However, at low temperatures some difficulties with the growth of the epitaxial layers, having high crystalline quality, arise.