Cyclotron resonance over a wide temperature range, II. Silicon

Abstract

A systematic investigation of cyclotron resonance in silicon has been carried out at 8*8 mm wavelength throughout the temperature range 2 to 120 °K. Typical expressions for the reciprocal collision times derived from the width of the cyclotron resonance lines in high purity material are: light- and heavy-mass hole τ − 1 = 0.15 × 10 11 + 6 × 10 7 T 2 s − 1 ; electrons τ − 1 = 0.15 × 10 11 + 6 × 10 7 T 2 s − 1 . The acoustic lattice wave scattering is in good agreement with the corresponding mobility data, but measurements with samples having a range of impurity concentrations indicate that ionized impurity scattering does not contribute significantly to the cyclotron line width even when it has a very marked effect upon the mobility. There is an anomaly in the collision time for electrons at about 50 °K which can be explained in terms of resonant scattering from a deep attractive potential well. This anomaly is very similar to that found previously in germanium. The magnitude of the anomaly is greater in samples containing large concentrations of oxygen but it is not directly related to the total number of oxygen impurities. At low temperatures the residual scattering for both holes and electrons appears to arise from neutral scattering sites. These measurements do not indicate any temperature dependence in the effective mass parameters for holes up to 50 °K and for electrons up to 100 °K. There is, however, a small discrepancy between the present results and the previously quoted values for the electron effective mass parameter in the <100> direction.