Physical behavior of germanium under shock wave compression

Abstract

Abstract Shock wave compression measurements from 20 to 140 kb and resistivity measurements under shock wave compression to 40 kb are reported for Ge in the [111] orientation. The Hugoniot elastic limit is found to be 44 ± 4 kb and a phase transition in the pressure range from 114 to 122 kb at about 160°C is identified. The transition occurs at a volume between 0.870 V0 and 0.880 V0. A shock wave velocity measurement in the mixed phase region allows the slope of the phase diagram to be determined as −3.1 × 10−2 kb °C−1. The pressure and volume data are in good agreement with the static work; these data, when combined with the slope of the phase diagram, clearly identify the transition as the solid-solid transition to the white tin structure. The observed exponential decrease of resistivity with elastic strain allows an energy gap change computation which agrees with theoretical calculations for silicon to 60%. Unusual features of the band structure of one-dimensionally strained [111] Ge are discussed. The new technique developed is generally applicable for shock compression and resistivity measurements on semiconductors.