Abstract
By basing on the same physical model and treatment method, as used in our recent works [1, 2], we will investigate the critical impurity densities in the metal-insulator transition (MIT), obtained in n(p)-type degenerate [〖InP_(1-x) As_x (Sb_x),GaAs〗_(1-x) Te_x 〖(Sb_x,P_x),CdS〗_(1-x) Te_x (Se_x)]- crystalline alloys, 0≤x≤1, being due to the effects of the size of donor (acceptor) d(a)-radius, r_(d(a)), the x- concentration, and finally the high d(a)-density, N, assuming that all the impurities are ionized even at T=0 K. In such n(p)-type degenerate crystalline alloys, we will determine:(i)-the critical impurity density N_(CDn(CDp)) (r_(d(a)),x) in the MIT, as that given in Eq. (8), by using an empirical Mott parameter M_(n(p))=0.25, and(ii)-the density of electrons (holes) localized in the exponential conduction (valence)-band tails (EBT), N_CDn(CDp)^EBT (〖 r〗_d(a) ,x), as that given in Eq. (26), by using our empirical Heisenberg parameter, H_(n(p))=0.47137, as given in Eq. (15), according to: for given〖 r〗_d(a) and x, N_CDn(CDp)^EBT (〖 r〗_d(a) ,x)≅N_(CDn(CDp)) (r_(d(a)),x), with a precision of the order of 2.92×10^(-7) , as observed in Tables 2-8 in Appendix 1.In other words, such the critical d(a)-density N_CDn(NDp) (r_(d(a))),x), is just the density of electrons (holes) localized in the EBT, N_CDn(CDp)^EBT (〖 r〗_(d(a)),x), respectively.