The IR electromagnetic effect induced in the fine step bands of the (001) face of GaAs(Te) by applying an alternating field

The optical sensitivity of the excess impurity lone-pair electrons is discussed on the basis of the values of the IR reflection integral which were derived from the plasma edge profile of the (001) face of GaAs(Te) for eight levels of dopant concentration. From the analysis of the variation in the reflectivity including annihilation and creation of some fine step bands induced by applying an alternating electromagnetic field with frequency f = A × 10^m−1 (m = 1, 2, …, 7) parallel to the <100 > direction, we estimate that this sensitive effect may be induced primarily by the dynamical variation of the matrix elements of these oscillators, the values of which are determined by the dipole moments and oscillator concentrations. By using the Nf-R relations of the fine step bands measurable at 274 cm^-1, 290 cm^-1 and 315 cm^-1, the degree of variation in the effective oscillator concentration and the effective charge are estimated and reasonable values are obtained, by comparison with the Born effective charge the dipole-moments were determined. The step property of the nine fine step bands superimposed on the fundmental lattice band and the plasma edge is analysed for the two types of sample.