Threading dislocation classification for 4H-SiC substrates using the KOH etching method

Abstract

We have studied the threading dislocations of 4H-SiC substrates with different conductivity types by means of molten KOH defect selective etching.

Electronic and Optical Properties of Threading Dislocations in n-Type 4H-SiC

“…Molten-alkali etching is usually adopted to reveal dislocations in 4H-SiC, which removes strained atoms surrounding TDs and forms etch pits at the surface of 4H-SiC. 20,21 Researchers have established an empirical approach to distinguish TSDs from TEDs by assuming that the average size of the etch pits for TSDs is 1.6−2.1 times larger than that of the etch pits for TEDs. 22 and sizes of molten-alkali etched pits significantly vary with the alkali species, etching duration, and doping concentration of 4H-SiC, makes it difficult to discriminate.…”

“…Molten-alkali etching is usually adopted to reveal dislocations in 4H-SiC, which removes strained atoms surrounding TDs and forms etch pits at the surface of 4H-SiC. , Researchers have established an empirical approach to distinguish TSDs from TEDs by assuming that the average size of the etch pits for TSDs is 1.6–2.1 times larger than that of the etch pits for TEDs . However, the shapes, densities, and sizes of molten-alkali etched pits significantly vary with the alkali species, etching duration, and doping concentration of 4H-SiC, makes it difficult to discriminate. − More significantly, both synchrotron X-ray-topography (XRT) and transmission-electron-microscopy (TEM) investigations have verified that TMDs are the dominant configurations of TSD/TMDs in 4H-SiC. , However, the morphology of the etch pits of TMDs is still ambiguous, which leads to difficulty in the statistics of the density of TMDs in 4H-SiC.…”

Investigation on dislocation and deflection morphology of PVT-grown on-axis 4H-SiC crystals

“…TSDs and TEDs with similar morphologies are distinguished relying on their sizes [12][13][14]. However, the etch pit sizes varied with the change of etching time and temperature.…”

“…In order to further analyze the discrepancy of etch pits, details of the investigated etch pits have been observed by In dislocation theory, both TSDs and TEDs extend along the growth direction in a silicon carbide. The Burgers vector of TEDs is perpendicular to the [0001] direction and the feature of an edge dislocation stress component is a function of [11][12][13][14][15][16][17][18][19][20] and direction. They are etched along the dislocation line, resulting in smooth inner wall, as shown in figures 4(a) and (a ′ ).…”

“…The Burgers vector components of TMDs are not only parallel but also perpendicular to the crystal growth direction. Therefore, high strain energies exist in [11][12][13][14][15][16][17][18][19][20], and [0001] directions around a mixed dislocation. Two etching mechanisms act on a mixed dislocation simultaneously [15], as shown in figures 6(a) and (a ′ ).…”