Investigations of photo-assisted conductive atomic force microscopy on III-nitrides

We have employed photo-assisted conductive atomic force microscopy (PA-CAFM) to obtain high-resolution current images on III-nitride surfaces. From the statistical results of current distribution, it is revealed that the full-width at half-maximum (FWHM) value is very sensitive to the dislocation density of III-nitride films even if the dislocation density is very low (∼108 cm−2), suggesting that the FWHM value of current statistics can be an indicator of III-nitride quality. The results acquired by PA-CAFM are consistent with those obtained from etching-pit density and X-ray diffraction measurements. In addition, it is also revealed that PA-CAFM can observe the current distribution of InN dots without external bias influences, directly indicating the dependence of InN dots and dislocations. Our experimental results indicate that PA-CAFM is a promising method for investigating the electrical and structural properties of a nanometric area in III-nitride materials.