Capacitance-Voltage Profiling On Polar Iii-Nitride Heterostructures

It has been long recognized that the capacitance-voltage (C-V) profiling technique only yields an apparent carrier concentration (n) over cap, which, in general, differs from the majority carrier concentration. However, it is still possible to extract the conduction band offset Delta E-c and interface charge sigma(i) from (n) over cap, provided the doping profile and the exact hetero-interface position are known. We will show that in the case of sigma(i) similar to 10(12) cm(-2), which is typical for the polar III-nitrides, an interface misplacement as small as 1 nm leads to a large error in the extracted Delta E-c, making the technique challenging to use, even with the help of a computer-assisted reconstruction. We used one-sided p(+)-n junctions to experimentally investigate sigma(i) and Delta E-c for Ga-face n-N GaN/AlGaN heterostructures through C-V profiling. The extracted sigma(i) matched the polarization charge reported by others. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4757940]