Mn Impurity in Bulk GaAs Crystals

M. Pawłowskia,b, M. Piersaa, A. Wołośb, M. Palczewskaa, G. Strzeleckaa, A. Hrubana, J. Goskb,c, M. Kamińskab and A. Twardowskib aInstitute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warszawa, Poland bInstitute of Experimental Physics, Warsaw University, Hoża 69, 00-681 Warszawa, Poland cFaculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warszawa, Poland

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Received: 4 06 2005;

Magnetic and electron transport properties of GaAs:Mn crystals grown by Czochralski method were studied. Electron spin resonance showed the presence of Mn acceptor A in two charge states: singly ionized A- in the form of Mn2+(d5), and neutral A0 in the form of Mn2+(d5) plus a bound hole (h). It was possible to determine the relative concentration of both types of centers from intensity of the corresponding electron spin resonance lines. Magnetization measured as a function of magnetic field (up to 6 T) in the temperature range of 2-300 K revealed overall paramagnetic behavior of the samples. Effective spin was found to be about 1.5 value, which was consistent with the presence of two types of Mn configurations. In most of the studied samples the dominance of Mn2+(d5)+h configuration was established and it increased after annealing of native donors. The total value of Mn content was obtained from fitting of magnetization curves with the use of parameters obtained from electron spin resonance. In electron transport, two mechanisms of conductivity were observed: valence band transport dominated above 70 K, and hopping conductivity within Mn impurity band at lower temperatures. From the analysis of the hopping conductivity and using the obtained values of the total Mn content, the effective radius of Mn acceptor in GaAs was estimated as a = 11 ± 3 Å.

DOI: 10.12693/APhysPolA.108.825 PACS numbers: 71.55.Eq, 72.20.Ee, 75.50.Pp, 76.30.Fc