Physical Vapor Transport Growth and Properties of SiC Monocrystals of 4H Polytype

Abstract

The physical vapor transport technique can be employed to fabricate large diameter silicon carbide crystals (up to 50 mm diameter) exhibiting uniform 4H‐polytype over the full crystal volume. Crystal growth rate is controlled to first order by temperature conditions and ambient pressure. 4H‐polytype uniformity is controlled by polarity of the seed crystal and the growth temperature. 4H‐SiC crystals exhibit crystalline defects mainly in the form of dislocations with densities in the 104 cm—2 range and micropipe defects, the latter having densities as low as 10 cm—2 in best crystals. Electrical conductivity in 4H‐SiC bulk crystals ranges from <10—2 Ω cm, n‐type, to insulating (>1015 Ω cm) at room temperature.

New materials for radiation hard semiconductor dectectors

“…To achieve high resistivity SI SiC, vanadium is incorporated into the crystal during growth, acting as an amphoteric deep dopant. Various growth techniques have been developed to produce large-area single crystal SiC, including the modified Lely method ) and by physical vapour transport (Barrett et al 1993;Hobgood et al 1994;Augustine et al 1997). The main commercial growth technique for SiC substrates is physical vapour transport, with material available from Cree and a number of other suppliers (eg.…”

On-axis homoepitaxial growth on Si-face 4H–SiC substrates

“…Among those only one with successful homoepitaxy; however, the work was conducted on C-face substrates [19]. C-face seed crystals are generally used for the bulk growth of 4H-SiC while bulk growth using Si-face seed crystals often results in switching of polytype to 6H-SiC [20]. This shows that the C-face has better polytype stability for 4H-SiC growth.…”

Role of micropipes in the formation of pores at foreign polytype boundaries in SiC crystals

“…However, the controlled formation of a designed SiC polytype, either a bulk crystal or a layer, is difficult. For SiC crystals grown by the modified Lely technique, 1 the polytype occurrence and stability depend on the growth conditions and orientation of the substrate, [2][3][4][5][6] as well as on the probability of formation of singular faces during growth. 7 Even though the conditions for stable growth of a single polytype were developed, [2][3][4][5][6]8 uncontrolled formation of inclusions of other polytypes might occur.…”

“…[11][12][13] MPs were supposed to nucleate at low-angle boundaries between a polytype inclusion and a matrix. 3,4,14 The evolution of polytype boundaries via the formation of microcracks was addressed by Siche et al 15 They assumed that dislocation bundles in the basal plane, located within and near the MPs, and the stress concentrated at the MP surfaces might generate microcracks. This statement was supported by the results of optical and electron beam induced current investigations.…”