banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Scanning capacitance microscopy studies of unintentional doping in epitaxial lateral overgrowth GaN
Rent this article for


Image of FIG. 1.
FIG. 1.

Cross-sectional images of the ELOG structures. [(a)–(c)] Taken with contact-mode AFM in parallel to the SCM data collection. [(d)–(f)] Taken with SEM on different areas of the same sample. (a) and (d) show sample A. (b) and (e) show sample B. (c) and (f) show sample C.

Image of FIG. 2.
FIG. 2.

SCM phase data for (a) sample A, (b) sample B, and (c) sample C. Black areas are n-type, white areas are p-type, and noisy areas have no detectable conductivity.

Image of FIG. 3.
FIG. 3.

SCM amplitude data for (a) sample A, (b) sample B, and (c) sample C. For regions which the SCM phase data show to be doped, SCM amplitude data show brighter contrast for areas with a lower doping concentration. Note that p- and n-type materials of the same gray shade may have different carrier concentrations as p- and n-type GaN respond differently to the SCM bias.

Image of FIG. 4.
FIG. 4.

SCM data were taken for sample D. (a) shows the raw SCM amplitude signal. The region of the dopant staircase contained in the gray box in (a) was used to make the calibration curve shown in (b). [Please note that the SIMS data in (b) are plotted on a log scale.] By using the calibration curve in (b), it was possible to obtain estimates of the n-type carrier concentrations marked by crosses in (a).

Image of FIG. 5.
FIG. 5.

A schematic representation of the ELOG growth mechanism.

Image of FIG. 6.
FIG. 6.

Schematic representations of GaN coalescence without magnesium. (a) ELOG: here the GaN grown through the mask (dark) forms perfect triangular cross sections. (b) ELOG: here the GaN grown through the mask (dark) still exhibits (0001) facets at the start of the coalescence step. During coalescence, material grown on inclined facets (medium gray) exhibits greater dopant incorporation than the GaN grown on the (0001) facets (light gray). (c) A similar orientation-dependent dopant incorporation mechanism could be responsible for the roughness of the uid interface layer found in some GaN samples adjacent to the sapphire substrate. Note that here the dark gray represents the 3D islands produced in the early stages of growth.

Image of FIG. 7.
FIG. 7.

A SCM phase image of a sapphire:GaN interface at which n-type conductivity can be observed. Note that the n- to undoped-GaN interface is rough.


Generic image for table
Table I.

Estimated carrier concentrations for the regions marked with white crosses in Fig. 4(a). The errors on these carrier concentrations are estimated to be .


Article metrics loading...


Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Scanning capacitance microscopy studies of unintentional doping in epitaxial lateral overgrowth GaN