A mechanical apparatus designed for use in deep level transient spectroscopy (DLTS) experiments and capable of applying more than 5 GPa pressure to a semiconductor crystal sample at temperatures from 300–450 K is described. This compound lever system applies a temperature‐independent stress to the sample throughout the temperature range of interest. As an illustration of this device’s application, the initial result of a uniaxial stress DLTS experiment on EL2 inn‐GaAs is given. EL2 is found to split under the [100] uniaxial stress, denying the AsGaand AsGa–Asimodels.