Atom probe tomography of AlInN/GaN HEMT structures

Abstract

Articles you may be interested inUltrathin InAlN/GaN heterostructures on sapphire for high on/off current ratio high electron mobility transistorsThe authors report a correlated study of the atom probe tomography (APT) of lattice matched AlInN/GaN and strained AlGaN/GaN high electron mobility transistor structures, before and after exposure to 60 Co irradiation. The AlInN/GaN exhibited a decrease in carrier density while the AlGaN/GaN was found to be more radiation tolerant. Analysis of the APT data revealed that the buried interface near the channel exhibited a much larger increase in isosurface roughness at the AlInN/GaN than at the AlGaN/GaN interfaces. This is believed to contribute to the scattering of carriers out of the channel, and the resulting deterioration of the charge transport characteristics. A proxigram analysis showed that the observed increased roughness at the AlInN/GaN heterointerface was not concurrent with a significant change in its diffuseness.

Practical Issues for Atom Probe Tomography Analysis of III-Nitride Semiconductor Materials

“…However, in every case a long Ga tail is observed penetrating into the layer which had been assumed to be pure InAlN with an amount of <1 at.%. The unexpected incorporation of Ga into InAlN, in the absence of any Ga flux, was previously attributed to the residual Ga-containing materials in the growth environment (Choi et al, 2014; Kim et al, 2014; Smith et al, 2014) and possible inter-diffusion from the underlying GaN layer (Zhu et al, 2012; Dawahre et al, 2013). Our XRD analysis of the In content of this layer assumed that the InAlN layer did not contain any Ga.…”

“…This was attributed to the difference in electric field required to evaporate different elemental species from the material, leading to uncontrolled evaporation and hence preferential loss of nitrogen or nitrogen-containing ions from the experiment. Dawahre et al (2013) identified a similar limitation. In addition, that study also attempted HV-pulsed APT analysis of a bulk GaN material.…”

“…In this work, the FIB-induced Ga implantation with different “clean-up” voltages was experimentally evaluated using an InAlN layer grown on a c -plane GaN pseudo-substrate. InAlN/GaN structures are relevant to, for example, fabrication of high electron mobility transistors (Dawahre et al, 2013). The motivation for using InAlN rather than GaN in our experiment was to facilitate the observation of Ga from FIB implantation.…”

Validity of Vegard’s rule for Al1−xInxN (0.08 < x < 0.28) thin films grown on GaN templates

“…It is worth noting that APT analysis of the stoichiometry of Table 1. Relaxed lattice parameters of the binaries AlN [42] and InN [43] and stiffness coefficients [43,44] III-nitride materials is significantly dependent on the parameters used in the APT experiment for reasons which are still under debate [35,[49][50][51][52]. Nevertheless, for the analysis of both In 1-y Ga y N and Al 1−x In x N, the measured fraction of metallic sites occupied by In atoms has been found to be relatively stable to the running conditions [53].…”

Elemental Quantification and Visualization of GaN Structures using APT and SIMS

“…SIMS analysis on the samples showed expected depth profiles and provided an accurate measurement for comparison with the atom probe data. In figure 2b, the SIMS data is overlaid on the APT 1D profile (which has been adjusted for background and N deficit [7]). After these corrections, the atom probe analysis achieved a quantification level for a volume of 2.5×10 -17 cm 3 of less than 2×10 19 atoms/cm 3 (0.02%) for all the implanted species.…”