Reduction in dislocation densities in 4H-SiC bulk crystal grown at high growth rate by high-temperature gas-source method

Abstract

We performed fast growth of a 4H-SiC crystal using the gas-source method and investigated the crystal to reveal changes in dislocation densities along the growth direction. The remarkable reduction in densities of threading and basal plane dislocations to be less than 1/10 and 1/20, respectively, was confirmed in the crystal grown at ∼3 mm h−1. The change in radial distribution of threading dislocations indicates enhanced reduction in dislocation densities within an area containing high density dislocations. We discussed possible mechanisms which could explain declining densities of threading dislocations according to the results obtained by classifying threading dislocations into each Burgers vector.

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

“…8,10,11 Nowadays the density of device-killing MPs is lowered down to ∼0.1 cm −2 in 4H-SiC substrates, while the densities of TEDs, TSDs, and TMDs remain in the order of magnitude of 10 3 −10 4 cm −2 . 12,13 TEDs and TSDs in 4H-SiC epitaxial layers are usually inherited from 4H-SiC substrates, and are found to increase the leakage current and premature breakdown of 4H-SiC-based power devices. 14−16 Furthermore, TDs in n-type 4H-SiC substrates act as the nucleation centers of stacking faults and basal plane dislocations (BPDs), which lead to the degradation of 4H-SiCbased bipolar devices.…”

“…Therefore, understanding the properties of dislocations in n -type 4H-SiC is important to understand the performance of 4H-SiC power devices. Despite the decades of development of the single-crystal growth and homoepitaxy of 4H-SiC, high-density threading dislocations (TDs) remain in 4H-SiC. , TDs usually originate from heterogeneous inclusions, silicon droplets, seed crystals, thermal stress, and mechanical stress. − TDs in 4H-SiC can be classified into threading edge dislocations (TEDs), threading screw dislocations (TSDs), threading mixed dislocations (TMDs), and micropipes (MPs), with the Burgers vectors of (⟨11–20⟩ a )/3, ± c , c + a , and ± nc ( n = 3–10), respectively. ,, Nowadays the density of device-killing MPs is lowered down to ∼0.1 cm –2 in 4H-SiC substrates, while the densities of TEDs, TSDs, and TMDs remain in the order of magnitude of 10 3 −10 4 cm –2 . , TEDs and TSDs in 4H-SiC epitaxial layers are usually inherited from 4H-SiC substrates, and are found to increase the leakage current and premature breakdown of 4H-SiC-based power devices. − Furthermore, TDs in n -type 4H-SiC substrates act as the nucleation centers of stacking faults and basal plane dislocations (BPDs), which lead to the degradation of 4H-SiC-based bipolar devices. − Therefore, it is imperative to understand the basic properties of TDs in 4H-SiC, which may help the optimization of 4H-SiC by manipulating the properties of TDs.…”

Nondestructive microstructural investigation of defects in 4H-SiC epilayers using a multiscale luminescence analysis approach

“…1 and 2), and CL was used to provide better spatial and spectral information (Figs. [3][4][5]. This work highlights the power of multiscale luminescence analysis using these two complimentary techniques to examine the relationship between the microstructure and optical properties of any features found in epitaxially grown 4H-SiC.…”

“…The typical densities of threading screw dislocations, threading edge dislocations, and basal plane dislocations (BPDs) in commercial 4H-SiC substrates can be 10 2 -10 3 , 10 3 -10 4 , and 10 2 -10 4 cm −2 , respectively. 4 This does not account for the 2D defects (e.g., planar stacking faults) generated from these dislocations nor the 3D defects (e.g., epi-pyramids and inclusions) in the epilayer. Thus, even though very high voltage bipolar devices and metal oxide semiconductor field effect transistors (MOSFETs) are readily available on the market, their potential has not been fully reached.…”

Nitrogen-Dependent Electronic Properties of Threading Edge Dislocations in 4H-SiC

“…The density of threading edge dislocations (TEDs) is the highest in 4H-SiC substrates among all types of dislocations. 6,7 During the homoepitaxy of 4H-SiC, the density of TEDs increases because over 95% of TEDs are inherited from the substrates to epitaxial layers. In the meantime, over 95% of basal plane dislocations (BPDs) in the substrates are converted to TEDs during the growth of the epitaxial layers.…”