Determination of carrier capture cross sections of traps by deep level transient spectroscopy of semiconductors

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Abstract
The conventional method of determining trap capture cross sections by deep level transient spectroscopy (DLTS) of semiconductors involves observing the DLTS peak amplitude as a function of filling pulse duration. Pulses that are inconveniently short and time‐consuming experimental measurements may be required. A method is proposed that involves observing the DLTS peak amplitude change as the observation rate window (t2−t1) is varied for a fixed‐duration filling pulse. This gives consistent results for the capture cross section and its dependence on temperature. Analysis of the technique is given and a comparison between theory and experiment is presented for two electron traps in bulk n‐GaAs. For the trap at EC‐ 0.215 eV, σ∞ is 2.3×10−15 cm2 and the activation energy from σ(T)=σ∞ exp(−Eσ /kT) is 0.116±0.003 eV. For the trap at EC ‐0.35 eV, the cross section σ∞ is 1.0×10−13 cm2 and the activation energy is 0.200±0.025 eV. Large variations of cross section with temperature such as these have been reported in other studies, and are a consequence of lattice relaxation effects.