Correlation between Stacking Faults in Epitaxial Layers of 4H-SiC and Defects in 4H-SiC Substrate

doi:10.15541/jim20180443

Abstract

Abstract:

The morphology and causes of stacking faults (SF) in homoepitaxial layers of 4H-SiC were studied. According to characteristics of PL images and morphology images of 4H-SiC five kinds of SFs have been defined. In the PL images, the morphologies of SF I and SF II-V are trapezoidal and triangular, respectively. SF II lays inside the area of SF I. In the morphology images, SF I and IV are not seen, SF II-III are carrot shaped and SF V is triangular respectively. The results show that SF I is a kind of base plane SF which originates from the base plane dislocation (BPD) lines of the substrate, parallel to <1$\bar{1}$00> direction and moving along <11$\bar{2}$0> direction during epitaxial growing. SF II and most of SF III-IV originate from BPDs in substrate. One BPD converts into threading dislocation during epitaxial growing and propagates to the surface along <0001> direction, while other BPDs or partial dislocations originating from threading dislocation propagate in (0001) plane to form triangular base plane SFs. The rest of SF III-IV and SF V originate from TED or other defects in substrate. SF II-III display carrots morphology because a prism SF plane perpendicular to the (0001) plane is formed to intersect with surface during epitaxial growing process. SF IV is not seen in the morphology image because no prism SF plane is formed to intersect with surface. All results demonstrated that reducing BPDs of the substrate is especially important for reducing SFs in the epitaxial layers.

Key words: SiC, homoepitaxial, dislocation, stacking fault

CLC Number:

GUO Yu, PENG Tong-Hua, LIU Chun-Jun, YANG Zhan-Wei, CAI Zhen-Li. Correlation between Stacking Faults in Epitaxial Layers of 4H-SiC and Defects in 4H-SiC Substrate[J]. Journal of Inorganic Materials, 2019, 34(7): 748-754.

Figures/Tables 9

Fig. 1 SF images tested by CS920 (a) PL images excited by 355 nm wavelength; (b) morphology images

Fig. 2 Originations and propagations of SF I and SF II<11$\bar{2}$0> is the direction of lower steps of crystal growth. D1-D6 are the moving distances of BPD lines. H1-H6 are the removing thickness of epitaxial layers

Table 1 Relationship of moving distance D of BPD lines and removing thickness H of epitaxial layers in Fig. 2

No.	1	2	3	4	5	6
Moving distance of BPD lines, D/μm	33	57	44	94	60	39
Removing thickness, H/μm	2.3	4	3.1	6.6	4.2	2.7

Table 2 Nitrogen concentration in substrate and epitaxial layers tested by SIMS

Test position	Substrate	Epitaxial layers
N concentration	8×10¹²	<10¹⁰

Fig. 3 Propagation diagrams of (a) SF I, (b) SF II, (c)-(d) SF III, and (e)-(f) SF IV

Fig. 4 Originations and propagations of SF III<11$\bar{2}$0> is the direction of lower steps of crystal growth. D1-D4 are the moving distances of BPD lines. H1-H4 are the removing thickness of epitaxial layers

Fig. 5 Originations and propagations of SF IV<11$\bar{2}$0> is the direction of lower steps of crystal growth. H1~H6 are the removing thickness of epitaxial layers. L1~L8 are bottom lengths of triangle defects. W1~W8 are widths of triangle defects

Table 3 Relationship of the moving distance D of BPD lines and the removing thickness H of epitaxial layers in Fig. 3

No.	1	2	3	4
Moving distance of BPD lines, D/μm	102	53	23	61
Removing thickness, H/μm	7.1	3.7	1.6	4.3

Table 4 Relationship of the moving distance D of BPD lines, the removing thickness H of epitaxial layers and width of trianagle defects W with bottom lengths of triangle defects in Fig. 3

No.	1	2	3	4	5	6	7	8
Moving distance of BPD lines, D/μm	34	-	36	-	50	-	-	-
Removing thickness, H/μm	2.4	3.8	2.5	12.9	3.5	2.9	-	-
With triangle defects, W/μm	85	51	85	49.0	85	35	85	35
Bottom lengths of triangle defects, L/μm	105	63	90	52	60	25	110	45

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