The high-index surface—a superlattice for two-dimensional electrons

Abstract

A review is given of low-temperature studies of the properties of the two-dimensional electron gas in inversion layers on high-index Si surfaces. The long crystallographic periods associated with such surfaces produce the superlattice effect in the spectrum of the quasi-two-dimensional electron gas. The kinetic coefficients are found to exhibit singularities when the Fermi level and minigaps cross. This was established by measuring the static and the high-frequency conductivities, the Shubnikov-de Haas oscillations, the photoresistivity, the emission of thermal electrons, and the cyclotron resonance in n-type inversion layers near (001) for electron concentrations in the range 1012 – 1014 cm−2. The minigap width varies from 1 to 20 meV, depending on the electron concentration. The position of the minigaps in K-space (but not their size) is in quantitative agreement with theory.