Distributed Bragg reflectors (DBRs) are essential components for the development of optoelectronic devices. For many device applications, it is highly desirable to achieve not only high reflectivity and low absorption, but also good conductivity to allow effective electrical injection of charges. Here, we demonstrate the wafer-scale fabrication of highly reflective and conductive non-polar gall...

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

Record-low sheet-resistance of $ 128 O=sq have been obtained in two-dimensional electron gases at ultrathin single AlN/GaN heterojunctions by optimizing the metal fluxes used in molecular beam epitaxy growth. Multiple 2DEGs have been found in AlN/GaN superlattices, with the net electron density measured 4 1 Â 10 14 cm À2 at room temperature. This very high electron density also leads to a furth...

A comprehensive methodology to qualify the reliability of GaN products 2 Introduction The industry takes the reliability of silicon power transistors for granted due to over thirty years of experience and continuous improvement. This longstanding experience has resulted in a mature qualification methodology, whereby reliability and quality are certified by running standardized tests. These test...

An approach by which single crystal a-GaN can be grown laterally over oxidized AlAs (AlOx) formed on Si substrates is demonstrated. Regular a-Ga2-O3 stripe templates, spatially separated by AlOx , on which subsequent GaN growth is selectively seeded are formed. Since the boundary between the stripe template and AlOx is nominally planar, two pyramidal planes on separated GaN can merge by growing...

High threading dislocation (TD) density in GaN-based devices is a long unresolved problem because of the large lattice mismatch between GaN and the substrate, which causes a major obstacle for the further improvement of next-generation high-efficiency solid-state lighting and high-power electronics. Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire su...

High-power operation of AlGaN/GaN high-electronmobility transistors (HEMTs) requires efficient heat removal through the substrate. GaN composite substrates, including the high-thermal-conductivity diamond, are promising, but high thermal resistances at the interfaces between the GaN and diamond can offset the benefit of a diamond substrate. We report on measurements of thermal resistances at Ga...

In this work, we present a method able to fabricate thin GaN nanomembranes fit for device applications. Starting from commercial GaN on sapphire substrates, MBE was used to deposit a sacrificial layer, which comprises of a superlattice of InN/InGaN, after which thin a GaN film of hundreds of nanometers thickness was grown on top. Pulsed laser irridiation with photon energy of 2.3eV gives rise t...

We report the fabrication of near-vertically elongated GaN nanorods on quartz substrates. To control the preferred orientation and length of individual GaN nanorods, we combined molecular beam epitaxy (MBE) with pulsed-mode metal-organic chemical vapor deposition (MOCVD). The MBE-grown buffer layer was composed of GaN nanograins exhibiting an ordered surface and preferred orientation along the ...

GaN nanowall network was epitaxially grown on Si (111) substrate by molecular beam epitaxy. GaN nanowalls overlap and interlace with one another, together with large numbers of holes, forming a continuous porous GaN nanowall network. The width of the GaN nanowall can be controlled, ranging from 30 to 200 nm by adjusting the N/Ga ratio. Characterization results of a transmission electron microsc...