The Atomic Heat of Silicon below 100°K

The atomic heat of Si containing less than 0.01 percent P-type impurities has been measured between 1^∘{}K and 100^∘{}K. Below 5^∘{}K, the atomic heat can be represented by the sum of a cubic term with Debye θ=658^∘{}K, and a linear term equal to that of a highly degenerate "hole gas" with concentration about 10¹⁸ cm^-3. This is also the hole concentration calculated from Hall constant measurements on this material. The Debye θ calculated from elastic constants is 653^∘{}K, using a simplified procedure (described in Appendix II) based on the Hopf-Lechner method. The atomic heat is in reasonable agreement with measurements of Nernst and Schwers above 20^∘{}K, and of Anderson above 60^∘{}K. Above 5^∘{}K, θ decreases to a minimum of 456^∘{}K at $T=40$^∘{}K and then rises to 580^∘{}K at $T=100$^∘{}K.The specific heat of glyptal lacquer, which was used to secure the heater and thermometer wires to the samples, was also measured. Below 15^∘{}K, it can be represented by c=2.2×10^-4T² joules/gdeg, and a table is given of values above this temperature.