Study of Dislocation Motion in GaAs and AlxGa1-xAs/GaAs Devices

摘要

The microscopic mechanisms of the interaction of dislocations with interfaces in AlGaAs/GaAs devices and of dislocation motion in GaAs during electron irradiation were studied using TEM. The results demonstrate new features concerning the interaction of dislocations with heterojunctions. The in situ TEM study of dislocation motion shows clearly the different mobility of Alpha, Beta and screw dislocations. The migration of kinks is shown to be particularly affected by electron irradiation. In GaAs-based devices, such as semiconductor lasers and LEDs, dislocation climb and glide during device operation can cause the degradation of the device. Under intense electron-hole recombination rapid dislocation climb can lead to the development of a dislocation network in the device. Such networks are believed to originate preferentially at heterojunction interfaces. Dislocation glide has also been shown, by dislocation velocity measurements, to be enhanced by the recombination of electron-hole pairs. The present paper will briefly report two new studies aimed at understanding the microscopic nature of dislocation interactions with heterojunctions and of dislocation motion under electronic excitation. The first topic is the investigation of dislocation motion through heterojunctions between GaAs and AlxGa1-xAs. The second topic is an in situ study of dislocation motion under electron irradiation in the TEM. Keywords: Dislocations(Crystal defects).