Local boron doping quantification in homoepitaxial diamond structures

Abstract

The capability of transmission electron microscopy (TEM) using the high angle annular dark field mode (HAADF, also labelled Z-contrast) to quantify boron concentration, in the high doping range between 10 19 cm − 3 and 10 21 cm − 3 , is demonstrated. Thanks to the large relative variation of atomic number Z between carbon and boron, doping concentration maps and profiles are obtained with a nanometer-scale resolution. A novel numerical simulation procedure allows the boron concentration quantification and demonstrates the high sensitivity and spatial resolution of the technique.Crown

Simulating realistic imaging conditions for in situ liquid microscopy

“…VTEM techniques for high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) have been shown to be so accurate as to replace the need for experimental calibration standards in compositional analysis [13]. Through VTEM, contrast features due to the environment, detector angles, specimen thickness, specimen orientation, defocus, aberrations, structural strain, interfaces, and composition have been determined [14–25]. As recent studies have demonstrated lattice fringe observations during in situ liquid experiments performed under BF-TEM or HAADF-STEM imaging modes [1, 26, 27], VTEM can provide insight into such high resolution contrast features observed in situ .…”

Cross sectional evaluation of boron doping and defect distribution in homoepitaxial diamond layers

“…Figure 3 shows the experimental and simulated HAADF intensities, with very good agreement between them. Details of how simulations are carried out have been published elsewhere [9]. As can z (nm) 80nm…”

Boron concentration profiling by high angle annular dark field-scanning transmission electron microscopy in homoepitaxial δ-doped diamond layers

“…Lett. 103, 042104 (2013) in SIMS measurements, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] leading to systematic overestimates of the real width, similar to the case of silicon. 26 If this is the case, it is legitimate to ask how the layer thickness should be estimated from broadened SIMS profiles.…”

“…The need of an imaging method able to quantify boron content and layer thickness becomes obvious when d-doped devices are being developed. For this reason, high angle annular dark field (HAADF 17 or Z-contrast mode) using a STEM (scanning transmission electron microscope) to thin homoepitaxial multilayers in order to determine the thickness, interface sharpness, and boron content of these doped structures is here applied. Recently, boron doping was also observed using this technique on nanocrystalline diamond.…”

“…However, the factor R corresponds to the ratio of the electron currents scattered onto the detector and not on the current delivered by the detector (R measured ). In order to take into account this response, an experimental calibration of the used equipment has been carried out using a thick (4 lm) diamond homoepitaxial single layer, with a well-known doping level (obtained from a previous calibrated SIMS measurement 17 ) at different thicknesses (controlled by the FIB related sample preparation) and different condenser apertures to vary the electron beam current. Brightness and contrast controls were kept at a fixed value (0 and 9, respectively) so that the correction factor C could be estimated for these experimental conditions.…”