GaN-Based Power HEMTs: Parasitic, Reliability and High Field Issues

Abstract

This paper reviews the main mechanisms responsible for trapping and breakdown in power HEMTs based on gallium nitride. With regard to the trapping mechanisms, we describe the role of carbon and iron buffer doping compensation in determining the dynamic Ron. We also demonstrate how the use of double heterostructure without doping or a single-heterostructure with proper buffer doping compensation can effectively reduce trapping phenomena. In addition, we investigate the breakdown limits of single and double heterostructure (DH) HEMTs, by electrical and electroluminescence characterization. Results indicate that, for the devices adopting double heterostructure without doping or singleheterostructure with proper buffer doping compensation, the breakdown voltage linearly scales with the gate-drain distance, and provides information on the origin of breakdown current components for different bias levels and epitaxial structures

Proton induced trapping effect on space compatible GaN HEMTs

“…But results from DCT or DLTS analysis on other irradiated samples [11][12][13], together with the results reported on this paper, suggest the presence of a deep electron trap placed 0.80 eV from the conduction band as the responsible for the slower (and enhanced after radiation) current transient (see Fig. 6 for comparison of the case study with other literature papers reporting the same trap signatures [11][12][13][14][15][16][17][18]). This point is still not clear because it does not fit with all the simulated results previously highlighted, and it points out a lack on the current available analysis of the radiation induced defects which needs to be better investigated.…”

Effects of buffer compensation strategies on the electrical performance and RF reliability of AlGaN/GaN HEMTs

“…Higher FWHM in C-doped wafers have also been observed by Wickenden et al [2] and Chen et al [20]. Complementary information on the effects of iron and carbon doping on the dynamic performance of AlGaN/GaN HEMTs are discussed by Uren et al [21] [22], Verzellesi et al [23], Meneghesso et al [24], and Meneghini et al [13].…”

Optimisation of a carbon doped buffer layer for AlGaN/GaN HEMT devices

“…With a corresponding transition level at 0.90 eV above the valence band maximum, C N will not produce p-doped GaN layers but it can make itself GaN semi-insulating by pinning the Fermi level, as foreseen in the theoretical work of Lyons et al [5]. The experimental evidence for this acceptor level has been reported by Honda et al [6], Meneghesso et al [7]. On the other hand, carbon acts as a shallow donor when incorporated on a Ga site [5].…”