...........................................................................................................................................1 CHAPTER I: INTRODUCTION ............................................................................................................2 OVERVIEW OF GAN HEMTS .......................................................................................................

The long-term stability of AlGaAs/GaAs and InAlAs/InGaAs high electron mobility transistors (HEMTs), tested under high drain voltage and/or high temperature operation is reported. HEMTs with high In content in the active channel, alternatively fabricated on InP substrates and on GaAs substrates covered by a metamorphic buffer (MHEMT), are compared. Despite the high dislocation density in the bu...

This paper presents the evaluation of heat generation behavior and related thermal measurement analysis of packaged high-power AlGaN/GaN high electron mobility transistors (HEMTs) cascaded with low-voltage MOSFET and SiC SBD. Since thermal management is extremely important for high power packaging, a hybrid integration of the GaN HEMTs onto a DBC substrate and metal case is proposed. We investi...

We present new normally off GaN high-electron-mobility transistors (HEMTs) that overcome the typical limitations in multi-mesa-channel (MMC) width through modulation of the via-hole-length to regulate the charge neutrality screen effect. We have prepared enhancement-mode (E-mode) GaN HEMTs having widths of up to 300 nm, based on an enhanced surface pinning effect. E-mode GaN HEMTs having MMC st...

The first demonstration of high-Al-composition (> 70%) AlGaN high electron mobility transistors (HEMTs) is reported. High electron mobility (∼1300 cm/Vs at room temperature) was achieved in novel high-Al-composition AlGaN 2-D electron gas structures. The threshold voltages (Vth) of Al0.72Ga0.28N/AlN/GaN HEMTs were shifted from −1.0 to −0.13 V by employing different gate metal stacks, Al/Au and ...

Superior electronic and thermal properties have made InAlN/GaN high-electron-mobility transistors (HEMTs) an attractive candidate for power electronics applications. However, their high gate leakage current remains a serious challenge affecting the reliability and performance of these heterostructures. Leakage paths through dislocations or by percolation through inhomogeneities in the InAlN all...

This paper discusses the background, applications, and proposed characterization of Gallium Nitride (GaN) based hybrid MOS-HEMTs for high-voltage power switching. The basic material properties, device structure, and basics of operation are discussed in section II. Section III touches on the relevance and motivation behind this research and some simple examples of where GaN based MOS-HEMTs would...

This study examined the effect of electronbeam (E-beam) irradiation on the electrical properties of n-GaN, AlGaN and AlGN/GaN structures on sapphire substrates. E-beam irradiation resulted in a significant decrease in the gate leakage current of the n-GaN, AlGaN and HEMT structure from 4.0×10 -4 A, 6.5×10 -5 A, 2.7×10 -8 A to 7.7×10 -5 A, 7.7×10 -6 A, 4.7×10 -9 A, respectively, at a drain volta...

We report on systematic measurements of resonant plasma waves oscillations in several gate-length InGaAs HEMTs and compare them with numerical results from a specially developed model. A great concern of experiments has been to ensure that HEMTs were not subject to any spurious electronic oscillation that may interfere with the desired plasma-wave spectroscopy excited via a terahertz optical be...

In this letter, we demonstrate 27% improvement in the buffer breakdown voltage of AlGaN/GaN high-electron mobility transistors (HEMTs) grown on Si substrate by using a new Schottky-drain contact technology. Schottky-drain AlGaN/GaN HEMTs with a total 2-μm-thick GaN buffer showed a threeterminal breakdown voltage of more than 700 V, while conventional AlGaN/GaN HEMTs of the same geometry showed ...