I am getting very low electrical conductivity of my semiconductor sample but i am not sure whether it is due to the low density or the material itself.
Varying of carrier density (n) will affect the mobility of semiconductor, thus change the material conductivity (sigma).
The detailed relationship between sigma and n depends on your material e.g. Si, GaAs or graphene. It also depends on external condition, such as temperature.
There is a minimum compaction density to get bulk conductivity. Less than that would result in conductivity that is dependant on the compaction density. Anyhow there paramters will also depend on grain size, sintering temperature, time, pressure etc. There are also other methods for compaction, for e.g. spark plasma sintering.