Optimization of the parameters of HEMT GaN/AlN/AlGaN heterostructures for microwave transistors using numerical simulation

The Influence of AlGaN Barrier-Layer Thickness on the GaN HEMT Parameters for Space Applications

“…Electron mobility in combination with a high-electron density in the region of the 2D electron gas makes it possible to implement high current densities in the transistor-channel cross-section and high gain. However, optimization of heterostructure transistors still remains a complicated and expensive procedure [1][2][3]. The results of numerical simulation and calculation for the AlGaN barrier layer of high-electron-mobility transistors (HEMTs) are shown in this paper.…”

“…In the first stage of the study, the numerical models [2,22,23] were adapted to the specific features of the configuration and fabrication technology of actual device structures. It is well known that the parameters of the undoped AlGaN barrier layer located near the two-dimensional electron channel have a significant effect on the characteristics of a HEMT.…”

Two-dimensional electron gas at the AlGaN/GaN interface: Layer thickness dependence

“…[16][17][18] There are also several practical reasons to control AlGaN thickness, which affects the gate leakage current, Schottky barrier at metal electric contacts, and 2DEG parameters. [19][20][21] It was found that a critical (minimal) thickness of the AlGaN layer is required in order to initiate the 2DEG. The further thickness increase affects both the electron density and mobility but with opposite tendencies: the former increases while the latter decreases with the thickness.…”

“…15 These tendencies again require a compromise yielding a rather narrow thickness interval, typically between 15 and 30 nm. [16][17][18]21 Nevertheless, the issue of critical thickness is rather poorly studied. The available publications about the critical thickness of AlGaN report that a layer of 4-6 nm is needed in order to enable 2DEG formation.…”

Quantitative SIMS depth profiling of Al in AlGaN/AlN/GaN HEMT structures with nanometer-thin layers

“…Such parameters as thickness, composition, and interface abruptness of the AlN sublayer have a strong effect on the electrical characteristics of the transistor structure. Along with the technological problems of obtaining such layers, the problem of diagnostics of HEMT structures with ultrathin layers is also topical. For example, in some papers dedicated, in particular, to thickness optimization of the AlN sublayer in HEMT structures, its thickness was determined indirectly by the nominal time of the layer growth.…”