EL2 family in LEC and HB GaAs

Abstract

Studies on the electrical and optical properties of EL2 in various GaAs crystals are described especially in view of the family characteristics. A variation in the trap energy levels among the EL2 family is first reviewed. It is shown that the family characteristics are also observed in the photoquenching effect (transitions between the normal and the metastable states) as well as the transition rate to the excited state. Change of EL2 centers after heavy particle bombardment and low temperature annealing indicate that the defect structure responsible for EL2 is sizable, in which mobile interstitial As atom(s) are involved. Based on the experimental results, validity of the As-cluster model for the origin of EL2 is presented and correlated with the models proposed by other investigators

Characterisation of deep electron states in LEC grown GaAs material

“…The reason that undoped LEC GaAs grown from stoichiometric or As-rich melt has a semi-insulating property has been considered to be that EL2 mainly compensates the residual carbon acceptor. Thus, much work has been reported on the EL2 state (for recent reviews, see, for example, Miyazawa et a1 (1988), Mochizuki and Ikoma (1988), Fillard (1988), Discher and Kaufmann (1988), Kaminska (1988), Stievenard and von Bardeleben (1988), Meyer (1988), Baraff and Lannoo (1988), Guillot 1988, Makram-Ebeid andBoher (1988), Bourgoin and Lannoo (1988), and references therein). Moreover, the microscopic structure of the native defects and their complex in GaAs has been investigated theoretically (Baraff and Lannoo 1988, Dabrowski and Scheffler 1988, Chadi and Chang 1988, and some atomic models of EL2 such as isolated AsGa (antisite arsenic) (Kaminska 1988), AsGa-VAs (As vacancy) pair (Lagowski et a1 1982a(Lagowski et a1 , b, 1986), As cluster (Mochizuki and Ikoma 1988), AsGa divacancy pair (Wagner and Van Vechten 1987) and AsG~-AsI (As interstitial) pair (von Bardeleben er a1 1986) have been proposed.…”

Characteristics of Deep Electron Levels in Oxygen-Implanted and (Oxygen + Silicon) Co-Implanted n-GaAs

“…Various atomic models have been proposed for these levels which are the resulting associations of an arsenic antisite with interstitial arsenic (Asi) [38 to 401, arsenic and gallium vacancies (VAs, VGa) [41 to 441. As-cluster models are also reported [45,46]. Theoretical considerations proposed that EL2 is the isolated antisite AsGa [47].…”