Strain Dependence of the Acceptor Binding Energy in Diamond-Type Semiconductors

It is shown that if the acceptor binding energy be expanded in inverse powers of the strain amplitude, $W\left(\epsilon \right)=W\left(\infty \right)+\frac{W_1}{\epsilon }+\cdots$, then the product $\frac{E_S{W}_1}{\epsilon }$, where $E_S$ is the strain-induced splitting of the band edge, may be equated to a certain (constant) quantity, $Z_0$, which is readily calculable in terms of the infinite-strain acceptor ground state. $Z_0$ is calculated for germanium with an uniaxial [100] compression. A provisional value of $W_1$, obtained from the existing data for this case, then gives the result $b=2.9\mathrm{}$ ev for the applicable deformation potential constant. An approach to the calculation of $W$ for arbitrary $\epsilon$ is suggested.