Photoluminescence Analysis of Individual Partial Dislocations in 4H-SiC Epilayers

Abstract

Configurations of the basal plane dislocations in 4H-SiC epitaxial layers are classified into two types, having typical combinations of ‘straight Si-core and straight C-core’ and ‘straight Si-core and curved C-core’ partial dislocations. The core species are determined by the photoluminescence images and observation of the moving Si-core partial dislocations by ultra-violet light illumination. Each partial dislocation was analyzed by photoluminescence spectroscopy. As the results, C-core partial dislocations have been found to have different peak wavelengths depending on the excitation power of the illumination. Also from the detailed analysis of individual partial dislocations, the curved C-core partial dislocations have been found to have different characters which may be originated from the mixture of different types of dislocations. It has been suggested that this model is possibly described by continuous connection of 30o and 90o dislocations which have different configurations of dangling bonds. The difference in photoluminescence peak wavelength might be explained by the structural difference.

Origin and Generation Process of a Triangular Single Shockley Stacking Fault Expanding from the Surface Side in 4H-SiC PIN Diodes

“…The 1SSFs of T1 and T3 had a right-angled corner on the right side, and these two types are the most frequently observed and repo rted. 3,[5][6][7][9][10][11][12][13][14]16,[19][20][21][22] However, the 1SSFs of T2 had a triangular shape with a right-and-left in contrast to T1 and T3. The expansion direction of T2, which was from the surface to the substrate/epilayer interface, was opposite to that of T3.…”

“…7 In addition, many analyses have been conducted of these 1SSFs, including current/temperature stress testing, [8][9][10][11][12][13][14] calculations, [15][16][17][18] and crystal analysis. [19][20][21][22][23] The BPD detection by photoluminescence (PL) imaging and the use of a buffer layer between the substrate and the epitaxial layer was proposed as a method for controlling 1SSF expansion 4,7,11,24 with the aim of solving the V F degradation issue.…”

Single Shockley stacking fault expansion from immobile basal plane dislocations in 4H-SiC

“…This curved line could not be explained by the elastic stress acting on the PD line but by the formation of a mixture of 30 °C-core and 90 °Ccore PDs. 40) In this epitaxially grown region, it is reasonable to think of the step flow during the epitaxial growth as the most effective driving force to bend the dislocation lines within the basal plane. This might be the reason why one of the immobile PDs changed into a mobile 30°Si-core PD.…”

“…28) Although 1SSF expansion and contraction phenomena have been closely examined experimentally [29][30][31][32][33] analytically, [34][35][36] and theoretically, 37,38) the structure of the PDs that constitute the 1SSF remains to be fully elucidated and demonstrated experimentally, particularly in real power devices such as PiN diodes. 39,40) According to the analytical approach, it has been concluded that the combination of 30 °C-core and 90 °C-core PDs in the BPD produce no expansion. 35) Finding the condition that can form these combinations is therefore a significant issue.…”

“…We previously found that there were 90 °C-core PDs at the curved line of the BPD. 40) Therefore, we assumed that the BPDs whose dislocation lines are toward the [1210] or [2110] direction would have this type of combination.…”