Hall and Seebeck measurement of ap-nlayer stack: Determining InN bulk hole transport properties in the presence of a strong surface electron accumulation layer

Measuring $p$-type transport properties by the Hall method in the presence of a parallel $n$-type carrier system with higher mobility is challenging as the measurement often indicates an apparent $n$-type conductivity. For example, the presence of the strong surface electron accumulation layer in $p$-type doped InN has thwarted even the qualitative assignment of $p$-type conductivity by Hall measurements. We present a method to determine the hole transport properties---resistivity, concentration, activation energy, and mobility---by combined multilayer modeling and Hall measurements of samples with different thicknesses of the $p$-type layer in parallel to a thickness-independent $n$-type carrier system. This method is further extended to determine the hole Seebeck coefficient, and can be generally used to determine the properties of one volume carrier system in any mixed ($p$ and $n$) conductivity stack. By applying this method to Mg-doped InN we unambiguously prove $p$-type conductivity by Hall measurements, and determine the hole transport properties, which reveal an unexpectedly high hole Seebeck coefficient at the present hole concentration.