Nitrogen incorporation characteristics on a 4H-SiC epitaxial layer

Abstract

The N incorporation characteristics on a 4H-SiC epitaxial layer were reinvestigated. It was found that the desorption process and thermally activated process are aspects of the N incorporation mechanism of 4H-SiC to which attention should be paid. This mechanism depends on both the rate-limiting condition and lattice polarity. The N desorption process dominates the N incorporation of the Si-face under the C-supply-limiting condition and that of the C-face without recourse to the rate-limiting condition. On the other hand, the thermally activated process dominates only the N incorporation of the Si-face under the Si-supply-limiting condition. The site-competition phenomenon was also found to depend on the rate-limiting condition.

Growth and characterization of nitrogen-doped C-face 4H-SiC epilayers

“…The decrease of doping concentration with C/Si ratio can be explained by the site-competition effect. Similar results have been reported on 81 off-cut C-face 4H-SiC epilayers in some recent papers [5,17]. However, earlier reports have shown that the doping incorporations on Cface 4H-SiC are independent of C/Si ratio [8,18].…”

Donor incorporation in SiC epilayers grown at high growth rate with chloride-based CVD

“…Theoretical studies have found that phosphorus atom prefers the silicon site in the SiC lattice [8], which has been confirmed by EPR studies [9,10] and growth experiments [7]. There have been several studies investigating the effect of different process parameters on the nitrogen atoms incorporation both experimentally [7,[11][12][13][14][15][16] and theoretically [17][18][19][20]; phosphorus incorporation has also been studied experimentally [7,13,21] and theoretically [22]. However, all these investigations are for the standard precursor mixture with silane and light hydrocarbons without any chlorine addition.…”

“…Previous studies have found that nitrogen incorporation on the C face material is more or less insensitive to the changes of the C/Si ratio at atmospheric pressure, and at normal growth temperature (1550-1600 1C) and with a C/Si ratio 41 [11,12], while some sensitivity to the changes in C/Si ratio for very low C/Si ratio at low pressure (150-350 mbar) and high temperatures (1730 1C) has been reported [14] and even more sensitivity is found at 250 mbar and 1600 1C [15,16]. The reports on nitrogen doping for the chloride-based low growth rate processes [23,24] confirm that the site competition theory is still applicable when chlorine is present.…”

“…The nitrogen incorporation was always found to be higher on the C face sample than on the Si face, which has been attributed to the differences in binding options for the incoming nitrogen atoms, where one atom on the C site of the C face can form three bonds to the silicon atoms, while one atom on the C site of the Si face can form only one bond to a silicon atom [16].…”

“…It should be noted here that the ethylene flow was decreased to compensate for extra carbon from the TBP molecule, keeping the total C/Si ratio in the gas mixture 1. It has previously been reported that nitrogen (N 2 ) used for n-type doping forms HCN and HNC species in the gas phase which does not contribute to the nitrogen incorporation but just consumes carbon in the gas phase [16]. The formation of CHP and HCP species in the gas phase during phosphorus doping has previously been pointed out by thermodynamical calculations [21].…”