Pressure-dependent compensation in InSb

High-purity n-type InSb exhibits an unusual temperature dependence in the Hall coefficient for pressures in excess of about 8 kbar. The behavior is explained using nonequilibrium semiconductor statistics and a model incorporating shallow donor and deep acceptor states. The best fit to experimental results is accomplished when the assumed number of acceptors exceeds the number of donors, although the material remains n type. Below 100 K, equilibrium is not achieved and the number of ionized acceptros is "frozen in" and replaces the total number of acceptors. This gives an apparent ratio of acceptors to donors very close to one. This model could explain, therefore, what appears to be fortuitously close compensation in many high-resistivity materials.