CVD Growth of 3C-SiC on 4H-SiC Substrate

Henry, Anne; Li, Xun; Kordina, Olof; Janzén, Erik

doi:10.4028/www.scientific.net/msf.711.16

Cited by 3 publications

(2 citation statements)

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“…The closer works mostly deal with Si surface modification before 3C-SiC growth [3]. As a matter of fact, Ge element could also be used for modifying 3C-SiC nucleation on on-axis α-SiC substrate in a comparative manner as when using the standard Si and C chemistry [4].…”

Section: Introductionmentioning

confidence: 99%

Ge Assisted SiC Epitaxial Growth by CVD on SiC Substrate

Alassaad

Soulière

Doisneau

et al. 2014

MSF

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This paper presents the results obtained after chemical vapor deposition of SiC with the addition of GeH4gas to the classical SiH4+C3H8precursor system. Epitaxial growth was performed either on 8°off-axis or on-axis 4H-SiC substrate in the temperature range 1500-1600°C. In the off-axis case, the layer quality (surface morphology and defect density) does not change though accompanied with Ge droplets accumulation at the surface. The Ge incorporation level was found to increase with temperature in the 10171018cm-3ranges. It was observed that adding GeH4leads to the increase of the n type doping level by a factor from 2 to 5 depending on the C/Si ratio. In the on-axis case, GeH4was only added to the gas phase before starting the SiC growth. It was found that there is a conditions window (temperature and GeH4flux) for which 3C-SiC twin free layers can be grown. Adding this foreign element before SiC growth clearly modifies SiC nucleation on on-axis substrate.

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Section: Introductionmentioning

confidence: 99%

Ge Assisted SiC Epitaxial Growth by CVD on SiC Substrate

Alassaad

Soulière

Doisneau

et al. 2014

MSF

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“…A solution to avoid degradation problem of the bipolar devices when using 8º or even 4 º off-cut materials is the use of nominally on-axis substrate which also reduces the production cost since the loss of material when slicing the wafers from the ingot will be lower. However, even if the problem of polytype instability with formation of 3C inclusions has been overcome and 100% 4H homoepitaxy has been demonstrated, the main drawback is related to the growth mechanism: spiral growth around screw dislocation is involved together with step flow growth in the regions where a very small off-cut angle exists and slightly higher than typically 0.3º, as reported in a recent book chapter [1]. This influences first the morphology with high roughness which increases with the thickness of the layer; steps as high as 7 µm have been observed on 100 µm thick epilayer.…”

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Homo-Epitaxial Growth on Low-Angle Off Cut 4H-SiC Substrate

Janzén

Henry

2014

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Abstract. The growth of 4H-SiC epilayers on 1.28º off-cut substrates is reported in this study and comparison when using standard 4º and 8º off-cut substrates is added. Growth at high temperature is needed for the polytype stability, whereas low C/Si is requested to decrease both triangular defects density and roughness of the grown surface. An in-situ etching with Si rich ambient allows the growth of epilayers with specular surface. The formation of Si droplets can be observed on the grown surfaces when lowering the growth temperature and appears first for the high off-cut angle. Introduction.A solution to avoid degradation problem of the bipolar devices when using 8º or even 4 º off-cut materials is the use of nominally on-axis substrate which also reduces the production cost since the loss of material when slicing the wafers from the ingot will be lower. However, even if the problem of polytype instability with formation of 3C inclusions has been overcome and 100% 4H homoepitaxy has been demonstrated, the main drawback is related to the growth mechanism: spiral growth around screw dislocation is involved together with step flow growth in the regions where a very small off-cut angle exists and slightly higher than typically 0.3º, as reported in a recent book chapter [1]. This influences first the morphology with high roughness which increases with the thickness of the layer; steps as high as 7 µm have been observed on 100 µm thick epilayer. Secondly large in-homogeneous distribution of minority carriers lifetime related to the growth mechanism has been observed [2]. Even if stable bipolar diodes without observation of degradation have been processed [3], the processing using on-axis material needs additional steps which reduce its yield.Thus the solution to avoid the propagation of the basal plane dislocations which are the origin of the bipolar devices degradation when using standard off-cut material and to get smoother surface than with nominally on-axis substrate is probably the use of very low off-cut angle substrate, as recently proposed [4][5][6], for which only step flow growth will appear. When using off-angle as low as 1º or just below it was necessary to lower the growth temperature below 1550 ºC and the C/Si ratio to 0.5 to get epilayers with good morphology without triangular defects and step bunching [6]. We can notice that the background level of the net doping concentrations is not mentioned in these reports [4,6].The main goal of this study is to investigate the growth on 1.28º off-cut substrate with standard chemistry.

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