Speaker
Lino Pereira
(IKS KU leuven)
Description
The lattice location of Mn in GaAs has been intensively studied in recent years due to its crucial role on the magnetic properties of Ga1−xMnxAs, one of the most studied dilute magnetic semiconductors. Maximum Curie temperatures (TC) are usually achieved after low temperature annealing (~200ºC), which is generally attributed to out-diffusion of interstitial Mn (MnI). However, despite major developments in film quality, the TC of Ga1−xMnxAs remains below room temperature even at very high Mn concentrations.
We report on the study of the lattice location of Mn in Ga1−xMnxAs by means of electron emission channeling from the decay of implanted 56Mn produced at ISOLDE/CERN. In addition to Ga1−xMnxAs thin films with x = 0.01 and x = 0.05, we have studied intrinsic GaAs, p+-GaAs and n+-GaAs. We locate the majority of the implanted Mn atoms in substitutional Ga sites and a significant fraction in tetrahedral interstitial sites with As nearest neighbors. Contrary to the general belief that interstitial Mn out-diffuses at ∼200ºC [1], we give evidence of its high thermal stability up to 400ºC. Showing that MnI is immobile up to temperatures where phase segregation is known to occur, we discuss strategies and prospects for achieving room temperature ferromagnetism in Ga1−xMnxAs.
Author
Lino Pereira
(IKS KU leuven)
Co-authors
A. Vantomme
(IKS-KU Leuven)
J.P. Araujo
(IFIMUP/IN Porto)
Joao Correia
(ITN)
M.R. da Silva
(University of Lisbon)
Ulrich Wahl
(ITN)
