The effects of 1MeV neutrons irradiation on the Hall mobility of n-GaAs obtained by MOCVD
H. El Ghazi1*, I. Zorkani1, A. Jorio1,2
1 Solid State Physics Laboratory, Faculty of Sciences, Dhar El Mahraz, Fes, Morocco
2 Regional center of interface, Sidi Mohammed ben Abdellah University, Fes, Morocco.
* Corresponding author. E-mail: email@example.com
Received: 28 October 2006; revised version accepted:02 August 2007
We present a study of neutrons irradiation effects on the Hall mobility of n type gallium arsenide (n-GaAs) obtained by the metal organic chemical vapour deposition (MOCVD) technique doped with Silicon donor (SiGa) at concentrations of 2.1015 cm-3 (UDS15) and 2.1016 cm-3 (UDS16). The UDS15 and UDS16 were irradiated with 1MeV neutrons and 15 MeV a particles at different fluencies. We have used photoluminescence (PL) measurement at 8.8K for the study of the irradiation effects on this sample before and after annealing at 550 0C during 30 minutes. The dependence of mobility on temperature is obtained for the samples after irradiation with and without annealing. The temperature, for which the electron mobility is maximum, is represented as function of the irradiation fluency. At high fluency, the mobility is degraded. We attribute this degradation to the density of the punctual and complex defects introduced by irradiation. The irradiation introduces in GaAs the gallium vacancy (VGa) and causes the amphoteric transfer of Si from the gallium site (SiGa) to the arsenic site (SiAs). Thus, some atoms donor’s impurities SiGa become under this effect the acceptors atoms SiAs. VGa and SiAs are acceptors defects which partly explain the degradation of the mobility in our samples after irradiation. The charge state of the defect introduced by irradiation is rationalized by transport measurements.
Keywords: Irradiation effects; Mobility; PL; MOCVD; Amphoteric.