Undulated Step Structure on the (000(1)over-bar) Facet of Physical Vapor Transport-Grown 4H-SiC Crystals

The step structure on the (000 (1) over bar )C facet of 4H-SiC boules grown by the physical vapor transport growth method with different nitrogen doping concentrations was examined in various scales, using different types of microscopy, such as differential interference contrast optical microscopy (DICM) and atomic force microscopy (AFM). DICM observations unveiled characteristic macroscopic surface features of the facet dependent on the nitrogen doping concentration. AFM observations revealed the existence of step trains of half unit-cell height (0.5 nm) on the facet and found that their separation was undulated with a characteristic wavelength dependent on the nitrogen doping concentration; the higher the nitrogen concentration, the longer was the undulation wavelength of step separation. Based on these results, we discussed the origin and formation mechanism of the separation-undulated step structure observed on the (000 (1) over bar )C facet of nitrogen-doped 4H-SiC boules.

Automated summary

Different microscopy techniques were used to examine the step structure on the (000 (1) over bar )C facet of 4H-SiC boules grown with different nitrogen doping concentrations. The observations revealed characteristic surface features dependent on the nitrogen concentration, with the separation wavelength of step trains varying with nitrogen doping concentrations. The height of the step trains was found to be half unit-cell height and the separation undulation had a wavelength depending on nitrogen concentration.