Use of dynamic compression to probe semiconductor response at large strains

Abstract

Phone: þ1 509 335 2498, Fax: þ1 509 335 6115Large strains in semiconductors are expected to be more common in future electronic devices utilizing nanostructure components. Hydrostatic pressure (HP) and uniaxial stress (US) loading have inherent limitations for probing the desired strain conditions. Uniaxial strain loading, achieved in dynamic compression experiments, is particularly attractive for attaining well-defined, large strains and to complement HP and US loading. Recent dynamic compression studies on III-V semiconductors (GaN, GaP, and GaAs) are summarized to review notable findings ranging from improved deformation potentials to free carrier properties. These findings demonstrate the benefits of dynamic compression experiments for semiconductor research. 1 Introduction Future electronic devices will increasingly incorporate semiconductor nanostructures to achieve novel optical and electrical properties. It has been demonstrated that these properties are determined not only by quantum confinement effects but also by the magnitude of lattice strains [1,2]. To achieve a comprehensive understanding of how these properties change in the presence of large strains, reliable predictions of the material's electronic structure are needed at these strain conditions. This need raises a fundamental question regarding the deformation potential (DP) theory: is this method, developed for determining electronic structure at low strains, accurate at large strains?The DP theory assumes that the electronic band modifications are described by the strain perturbation Hamiltonian consisting of the DP operators related to the elastic strain tensor e ij [3]. The exact form of the Hamiltonian was established by Bir and Pikus [4] for the Brillouin zone center and by Herring and Vogt [5] for the other degenerate conduction band minima. Two distinct groups of DPs can be assigned in these Hamiltonians depending on their effects on the electronic structure. The volume DPs induce only shifts of the energy states because they are related to hydrostatic or volume compression (e mm or the trace of the strain tensor), which preserves space group symmetry. In contrast, the shear DPs induce splitting of the degenerate energy states because they are related to strain deviators (e

High Pressure Semiconductor Physics

“…Probing semiconductors at highly anisotropic strains is diffi cult due to the inherent limitations of the commonly used static compression methods to generate the hydrostatic pressure or uniaxial stress. The uniaxial strain conditions produced during strong dynamic compression can overcome these limitations and have revealed lately important electronic structure changes [3]. From the more technological point of view several papers deal with investigations of laser diodes under high pressure.…”