AVS 59th Annual International Symposium and Exhibition
    Nanometer-scale Science and Technology Thursday Sessions
       Session NS-ThM

Paper NS-ThM11
Atom Probe Tomography of AlInN/GaN based HEMT Structures

Thursday, November 1, 2012, 11:20 am, Room 12

Session: Nanoscale Imaging and Microscopy
Presenter: N. Dawahre, University of Alabama, Tuscaloosa
Authors: N. Dawahre, University of Alabama, Tuscaloosa
G. Shen, University of Alabama, Tuscaloosa
P. Tolmer, University of Alabama, Tuscaloosa
S.M. Kim, University of Alabama, Tuscaloosa
P. Kung, University of Alabama, Tuscaloosa
Correspondent: Click to Email
Group III-Nitride semiconductors have been well known for their excellent optoelectronic properties associated with a wide direct bandgap, which has led to the emergence of blue and green lasers, ultraviolet-blue-green-amber and white light emitting diodes, and ultraviolet photodetectors. They are also rapidly becoming the material family of choice for next generation of RF-microwave devices, power amplifiers and high temperature electronics, thanks to high two-dimensional electron gas charge densities and high breakdown electric fields in these materials. GaN based materials are also more radiation resistant than conventional electronic materials, which makes them well suited for space electronics. Although less thoroughly investigated until now, lattice matched AlInN/GaN systems are promising to be a viable alternative to the current state-of-the-art strained AlGaN/GaN devices and their reliability issues.

In this work, we present the nanoscale characterization of AlInN semiconductors and AlInN/GaN high electron mobility transistor (HEMT) structures using a combination of transmission electron microscopy (TEM) and laser assisted atom probe tomography (APT), and correlate these with the structures’ electronic and optical properties, as well as the effects of irradiation. APT is an emerging technique based on the field ion emission from a needle-shaped region of interest and is capable of yielding 3D chemical mapping with atomic sensitivity and sub-nanometer spatial resolution. We report here a study of the field evaporation mechanisms from wide bandgap AlInN and GaN using a visible ps laser during APT experiments and correlate them with APT experiments (e.g. laser pulse energy, …) in order to establish approaches for reliable chemical analysis at the nanoscale of AlInN compound alloys. We proceed to investigate the fundamental material characteristics of interest that can be extracted from a combined APT and TEM analysis, including indium segregation phenomena in AlInN, interdiffusion near the AlInN/GaN channel interfaces and interface roughness, as well as the effects of irradiation on the channel properties.