Many-valley interactions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi></mml:math>-type silicon inversion layers

Abstract

Correlation effects between different conduction-band valleys have been studied experimentally for electrons in silicon inversion layers. The quantized subband systems were energetically shifted relative to each other by a uniaxial mechanical stress which modifies the conditions favoring intervalley coupling. Transport investigations such as magnetoquantum oscillations, piezoresistance, Hall mobility, and anisotropic conductivity were analyzed with respect to effective masses and relaxation times for (100), (110), and (111) surface orientations. All results are consistent with a domain model on the basis of charge-density waves as a stable ground state. A domain size of the order of 250 nm has been estimated for the (111) surface. The relaxation time has been found to be anisotropic for elliptical subbands.