Volt-ampere characteristics of InGaN/GaN-based structures at high level of injection

Background. Emitting heterostructures with quantum wells based on InGaN/GaN, are the subject of intensive research. Interest in such structures is associated with the wide practical use of LEDs: traffic lights, screens, digital displays, etc. However, at present, the mechanism responsible for reducing the efficiency of radiation in the field of high currents is debatable. The aim of this work is an experimental study of current-voltage characteristics of structures based on InGaN/GaN in the current range up to 1 A to determine the mechanisms responsible for the flow of current at different levels of injection. Materials and methods. To solve this problem, the current-voltage characteristics of the structure based on InGaN/GaN were measured in the current range up to 1 A and temperature range 25-90$^{\circ}C$. In the current range >40 mA, the current-voltage characteristics were measured in pulse mode with current registration using an oscilloscope. To analyze the obtained temperature current-voltage characteristics, a generalized recombination model was used, which allows describing the process of current transfer in a spatially disordered structure, when one of the stages of the process is tunneling. Results. The analysis of the temperature current-voltage characteristics of structures based on InGaN/GaN in the current range up to 1 A and the temperature range 25-90$^{\circ}C$. In the high current region was taken into account the voltage drop on the resistance of the bulk base of the structure. It was found that these characteristics can be divided into two sections - a section of a sharp increase in current with an increase in voltage in the current range <30 mA and a saturation section at currents > 30 mA. At the same time, a weak dependence on temperature is observed at the saturation site. Each of the sections of current-voltage characteristics is analyzed using the mechanism of generalized recombination model. Conclusions. On the basis of the generalized recombination model, it is shown that in the current range up to 30 mA, the main mechanism forming the current-voltage characteristics is the recombination of charge carriers in the structure under study (the current is proportional $exp(qU/2kT)$). In the current range of more than 30 mA, the limiting stage of the current transfer process is the tunneling process, the limitation of the tunneling channel capacity with an increase in the level of injection of the main charge carriers explains the saturation region on the volt-ampere characteristic of the structure under study.