Abstract
CRITICAL DENSITY IN METAL-INSULATOR TRANSITION, OBTAINED IN N(P)- TYPE DEGENERATE [ ]- CRYSTALLINE ALLOYS, AND EXPLAINED BY THAT OF CARIERS LOCALIZED IN EXPONENTIAL BAND TAILS. (III)
Prof. Dr. Huynh Van Cong*
ABSTRACT
By basing on the same physical model and treatment method, as used in our recent works (Van Cong, 2024), for various [ ]- and-[ ]- crystalline alloys, referred to as: I and II, we will investigate the critical impurity densities in the metal-insulator transition (MIT), obtained now in n(p)-type degenerate X(x) [ ]- crystalline alloys, due to the effects of the size of donor (acceptor) d(a)-radius, and the x- concentration, assuming that all the impurities are ionized even at T=0 K. In such n(p)-type degenerate X(x) -crystalline alloys, we will determine: (i)-the critical impurity density in the MIT, as that given in Eq. (8a), by using an empirical Mott parameter , noting that this one could be explained from the definition of the relative effective Wigner-Seitz (WS) radius in the MIT, being a constant for given as that given in Eq. (8b), and (ii)-the density of electrons (holes) localized in the exponential conduction (valence)-band tails (EBT), , as that given in Eq. (26), by using our empirical Heisenberg parameter, , as that given in Eq. (15), suggesting also that: for given and x, obtained with a precision of the order of , as observed in Tables 2-8. In other words, such the critical d(a)-density is just the density of electrons (holes) localized in the EBT, . So, if denoting the total impurity density by N, the effective density of free electrons (holes), given in the parabolic conduction (valence) band of the n(p)-type degenerate - crystalline alloy, can thus be defined, as the compensated ones, by: , needing to determine various optical, electrical, and thermoelectric properties in such n(p)-type degenerate X(x)-crystalline alloys, as those studied in n(p)-type degenerate crystals (Van Cong, 2023).
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