Thermodynamics of a charged fermion layer at high r(s) values

The chemical potential mu of a hole layer is mapped as a function of temperature and density p. We present the first investigation of the crossover from the strongly interacting degenerate regime to the classical ideal gas limit. The low temperature inverse compressibility, kappa(-1)= p(2) partial derivative mu/partial derivative p, is negative and temperature independent. At T approximate to 17 K temperature dependence commences abruptly: kappa(-1) turns less negative with rising T and eventually reverses sign. An ideal classical gas is attained at temperatures comparable to the interaction energy, more than an order of magnitude larger than the Fermi energy.