SiN passivation layer effects on un-gated two-dimensional electron gas density in AlGaN/AlN/GaN field-effect transistors

In this paper, we present a study of SiN passivation layer effects on the two-dimensional electron gas (2DEG) sheet density in unintentionally doped AlGaN/AlN/GaN heterostructures, using a polarization model based on interface charges and a fully numerical calculation. The analysis of our results clearly indicates that there are at least two occupied sub-bands in the 2DEG for passivated AlGaN/AlN/GaN heterostructures, and with increasing passivation layer thickness and AlN interlayer thickness the 2DEG density increases. The comparison of our calculated results with published experimental data is shown to be in a very good agreement. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3696641]