Atomic Investigation of Dopant Chemistry in GaN:Mg for an Enhanced N-polar Photocathode

Olivia Licata

Olivia Licata running a sample in the atom probe lab.

Olivia Licata running a sample in the atom probe lab.

Graduate Student Project

Introduction

Here, at the University at Buffalo, we have the ability to image materials at the atomic scale and know the identity and 3D position of each atom. Each day I have the opportunity to 'see' millions of atoms and learn how the material and structure can benefit new technology.

My name is Olivia Licata and I am a third year doctoral candidate at the University at Buffalo. I work with Dr. Baishakhi Mazumder as my mentor in the Department of Materials Design and Innovation.

We rely on power electronics in our daily lives. From the large-scale energy conversion of a wind turbine to the handheld optoelectronics of an LED light, all device components rely on material structure and atomic-level interactions. The insight that we gain at the atomic level, using Atom Probe Tomography, facilitates improved performance and efficiency for the next generation of power devices.

Abstract

Gallium nitride (GaN) materials are central to the design of power electronics and optoelectronics for energy conversion on the large scale and within handheld devices. A major challenge in the continued optimization of GaN-based optoelectronics is the limited enhancement of p-type conductivity through incorporation of Mg dopant. Furthermore, standard characterization methods are incapable of describing the distribution of light elements such as Mg in the GaN structure. Here, Atom Probe Tomography (APT), an inherently three-dimensional imaging technique, is utilized to reveal elemental distribution and segregation of dopant (Mg) in Mg-doped gallium nitride (GaN). Statistical analysis of APT data reports a reduced number of clusters within the sidewall of hillock structures. These results will aid in future enhancement and optimization of optoelectronic device structures.

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