Influence of PECVD features of SiNx deposition processes on electrical parameters of SiNx/AlGaN/GaN structures

In this work, we studied the influence of the processes of plasma-chemical deposition of SiNx films on the electrical parameters of the dielectric/AlGaN/GaN structure. The effect of the composition of the formed films, the effect of additional surface treatment of heterostructures in nitrogen plasma prior to dielectric deposition, as well as the effect of the RF bias supply during this treatment on the C-V and I-V characteristics of the SiNx/AlGaN/GaN structures were analyzed. It was found that for films with a ratio of nitrogen and silicon concentrations of 60 % and 40 %, as well as with an increased oxygen content, a decrease in the value of a fixed positive charge in these structures is characteristic, but the appearance of current pulsations is observed on the I-V characteristics of the structures. It was revealed how the modes of the plasma chemistry process affect such parameters of oscillations as the period, amplitude, length of the section of the I-V characteristic, where oscillations are observed. A possible explanation of the reasons for the appearance of characteristic pulsations is proposed. It has been established that the additional action of nitrogen plasma on the surface of the heterostructure before the monosilane is introduced into the chamber leads to a change in the magnitude and sign of the fixed charge and to a decrease in the concentration of free carriers in the channel of a two-dimensional gas of SiNx/AlGaN/GaN heterostructures. It is shown experimentally how the technological features of the deposition and surface preparation processes can affect the electrical parameters of the formed heterostructures.

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