Deep Level Transient Spectroscopy as an Experimental Technique

Résumé du livre

Deep Level Transient Spectroscopy (DLTS) is becoming a popular method of studying defect trapping states in semiconductors. DLTS is sensitive, rapid, and straightforward to analyze; it is able to distinguish between traps of different energy levels as well as different capture cross sections; and it is versatile in that it can provide any desired information on a given defect and can cover a large spectrum of energy levels. DLTS can be used on any type of semiconductor with little or no change in system setup. This makes it both a convenient and powerful technique. This report studies the DLTS technique and introduces a mathematical model of the DLTS data analysis which until now has been somewhat limited in scope. This analysis is considered under a wide range of system setups and its effects are shown graphically. The source of error which causes the greatest uncertainty in results in DLTS is found to be the accuracy with which the applied phase shift can be measured. The results are found to vary by one percent per degree of phase shift. The system is then used to evaluate trapping states in a sample of Silicon and a sample of GaAlAs. For the Silicon the Energy Level is .433 eV with a prefactor of 1.11 x 10 to the 7th power. For the GaAlAs the Energy Level is .59 eV with a prefactor of 5.24 million. Due to limitations of the DLTS apparatus it was not possible to determine the capture cross section of these samples. An electronic circuit is currently being developed to overcome this difficulty.