Acoustodynamic Effects in Semiconductors

Order and disorder in high-temperature long-wave acoustics (I): dielectrics, semiconductors, and conductors

“…Вероятно, впервые поглощение звука свободными носителями заряда было вычислено в [76], где считалось, что упругая волна за счет электронного дефор мационного потенциала возмущает края зоны проводимости и валентной зоны. В результате создается пространственно неоднородное распределение носителей, которое выравнивается за счет диффузионных процессов.…”

“…Вайнрейхом [76] была учтена модуляция ширины запрещенной зоны в собственном полупроводнике распространяющейся волной:…”

Internal friction in intrinsic and N-type germanium and silicon

“…The development of the theory in monopolar semiconductors is primarily [27][28][29][30][31] due to Weinreich, et al·, ' and their analysis will be followed here.…”

“…Specifically we can use the macroscopic current equation with the continuity equation to calculate the redistribution of carriers which takes place when an external field is applied in the form of an acoustic wave and then determine the effect of the nonequilibrium carrier distribution on the acoustic wave through the wave equation. 31 To avoid space-charge difficulties Weinreich considered not only the deformation potential, but also the force exerted by electric fields resulting from the redistribution of charges. In metals, since there is only one type of carrier available, the electric field essentially cancels the deformation field resulting in extremely small acousto-electric effects.…”

“…However, in semiconductors since both positive and negative current carriers are present rather large nonequilibrium distributions of excess carriers can occur. Therefore 31 Weinreich uses the common approximation, which is valid when the period of·the wave is much longer than the dielectric relaxation time and the acoustic wavelength much larger than a Debye length, that charge neutrality is maintained exactly, and that the electric fields necessary for this purpose are set up automatically and .instantaneously.…”