Effective mass and intrinsic concentration in silicon

Experimental observations bearing on density-of-states effective masses and on the intrinsic concentration in silicon are reviewed and correlated. These indicate effective masses to be temperature and energy dependent. The valence band structure as determined by Kane is used to calculate the temperature and donor density dependence of hole effective mass. A first order approximation to the explicit temperature variation of both hole and electron effective masses is made using the measured temperature dependence of the energy gap. When these temperature-dependent effective masses are substituted into the theoretical expression for intrinsic concentration the agreement with reported measurements of ni is within the limits of error. Density-of-states effective masses at 300°K are found to be me∗ = 1·18 and mh∗ = 0·81 in contrast to the generally used 4·2°K values of me∗ = 1·06 and mh∗ = 0·59.