Carrier Mobilities and Concentrations in SiC

and C-V, four-point probe and spreading resistance measurements to some extent provide a measure of the net impurity concentration of dopants in SiC ([ND - NA] or (Na - Nd]). In addition, Hall measurements provide a method for obtaining the mobility of the net carriers. These measurements have been applied to both n- and p-type SiC and its various polytypes. In this Datareview, we will report on the mobilities for most of the SiC polytypes under various growth conditions. 

The mobility and carrier concentration in SiC are functions of the polytype, growth technique, starting substrate doping conditions and temperature. The information that follows is divided into polytype and the growth technique information is also provided. We do not claim to report on all the known measurements, but a representative number. 

The following tables list the carrier concentrations, Hall mobility, conditions of the growth technique and polytype. In some cases, C-V and other measurement techniques have been employed. 

Ox 1016 All samples SiC platelets grown from carbon saturated [8] 

943 xlO17 TMA doped p-type on off axis with the substrate removed [11] 

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Values for both the hole and electron mobilities and carrier densities in various SiC polytypes are listed. Ionized and neutral impurity, acoustic phonon, piezoelectric and polar optical phonon scattering mechanisms are all found in SiC. In general, mobilities have increased and carrier concentrations decreased with time, reflecting the improvement in crystal quality whether bulk or epitaxially-grown material is considered. 

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