CRITICAL CONCENTRATION FOR THE METAL-NON METAL TRANSITION IN n-TYPE GERMANIUM AND SILICON

Abstract

The metal-non metal transition in n-type Ge and Si is considered by means of a model that has features in common with recent work on electron-hole droplets. The critical concentration is determined by comparing the energy of the metallic phase with the energy of an electron bound to a donor ion. Agreement with experiments is satisfactory and chemical shifts are reproduced. Previous estimates of the critical concentration are reviewed

On the impurity states in doped semiconductors via the alternant molecular orbital method

“…In the light of this approach one can find a general applicability of the Mott criterion x 10'' ~m -~, respectively [22]. Calculation on an electron-hole droplet model [23] gives N , = 5.6 x 10'' ~m -~. It is worth noting that in both schemes, i.e., disorder and regular lattice, the values of N , do not differ much and that the localization is completely discarded in our calculation.…”