Characterization of Trapping States in Semiconductors.
Final rept. 1980-1981,
NAVAL ACADEMY ANNAPOLIS MD
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Defect energy states within the band gap are known to affect the performance of semiconductors in terms of response time. The characterization of defects is the first step in understanding how they act and how one may use them to benefit diode performance. Characterization of a defect includes among other quantities, the energy difference from the band edge, and the capture cross section of the energy state. Deep Level Transient Spectroscopy DLTS is a very powerful experimental method using the transient capacitance properties reverse-biased p-n junction diodes to characterize defects. A particular electron trap in n-type GaAlAs, known as the DX center is studied in this report using two different DLTS experimental setups. A complex model is proposed for the DX center consisting of a group plus an excited state with independent capture cross sections and communication between the two levels. Since classical analysis of DLTS data yields misleading results when a complex trap is considered, a computer simulation and curve fitting technique was used to determine the trap structure and parameters. This technique gave values of .295 eV for the ground state energy, .219 eV for the excited state, prefactor values on the ground, excited, and communication prefactor of 1.02 x 10 to the 7th, 2.2 x 10 to the 8th and 5.58 x 10 to the 5th, respectively. Author
- Solid State Physics