Electron channelling contrast imaging for III-nitride thin film structures

Abstract

Electron channelling contrast imaging (ECCI) performed in a scanning electron microscope (SEM) is a rapid and non-destructive structural characterisation technique for imaging, identifying and quantifying extended defects in crystalline materials. In this review, we will demonstrate the application of ECCI to the characterisation of III-nitride semiconductor thin films grown on different substrates and with different crystal orientations. We will briefly describe the history and the theory behind electron channelling and the experimental setup and conditions required to perform ECCI. We will discuss the advantages of using ECCI; especially in combination with other SEM based techniques, such as cathodoluminescence imaging. The challenges in using ECCI are also briefly discussed

Probing the Local Electrical Properties of Al(In,Ga)N by Kelvin Probe Force Microscopy

“…Trench defects, in general, have been reported before in InGaN and in AlInGaN. It is had been proposed that they form due to basal plane stacking faults in InGaN multi‐quantum well structures and could be associated to local crystallographic misorientation especially present in AlInN or AlInGaN . There were no traces of stacking faults in samples B–D in our transmission electron microscopy results.…”

Exploiting Phonon‐Resonant Near‐Field Interaction for the Nanoscale Investigation of Extended Defects

“…It should be noted that in principle, atomic steps such as step bunching may also be observed via ECCI,18a,46 and are somewhat visible in Figure c above the secondary prismatic fault, where the sample surface is at the correct angle. However, imaging a larger area of these steps with ECCI requires the sample to be rotated so that the nonplanar surface in the vicinity of this defect can be held at the correct angle with respect to the detector for imaging, which was not utilized in these measurements and is not readily available in most commercial SEMs. As such, s‐SNOM provides an alternative, reliable method for characterizing step bunching, providing accurate measurements of the features.…”

“…To obtain nanoscale resolution, electron beam techniques are often used, such as cathodoluminescence, TEM or scanning electron microscopy (SEM) . Electron beam methods also include the powerful, but lesser‐known ECCI technique that has been explored for strain contrast imaging . In this method, the sample is tilted to an angle with respect to the electron beam that is slightly deviated from the Bragg condition.…”

Microscopy of defects in semiconductors

“…Until recently, ECCI was mostly used to investigate the structural properties of metals and geological materials, but its use for the characterisation of defects in semiconductors is steadily expanding. To date ECCI has been used to image defects in nitride semiconductors [22,23,24], Si1-xGex [34], SiC [35], GaAs [26], GaP [27,28], GaAsyP1-y [28], GaSb [29]. For more information on ECCI, the following papers provide informative reviews of the technique [21,29,34,35].…”