Magnetic field dependence of the specific heat of ‘just metallic’ Si : P

Abstract
The specific heat of two samples of phosphorus doped silicon has been measured from ∼ 0-1 to 1 K in zero field and a field of 2-2 Tesla. One sample which was ‘just insulating’ (1–8 × 1018 phosphorus/cm3) showed a large change in specific heat, negative below 0-5 K and positive above. The other sample was ‘just metallic’ (5 × 1018 phosphorus/cm3); there was no change in the specific heat within the scatter of ±3% of the data. It is concluded that the inhomogeneity model, which has localized and delocalized donor electrons coexisting, is not valid for the ‘just metallic’ doped semiconductor.