Persistent Photoconductivity and Magnetotransport in Dilute Nitride Semiconductor Alloys

Nitrogen related defects, such as N interstitials and Si-N complexes, are known to dominate electrical and optical properties of dilute nitride semiconductor alloys [1,2]. We investigate the dependence of these defects on N incorporation for MBE grown Si and Te-doped dilute GaAs$_{1-x}$N$_x$ ($x$ = 0.75-1.9) alloys. Persistent photoconductivity was observed for these heterostructures as high as 160 K, with photo-capture barriers from 216-350 meV. Also, carrier concentrations extracted from Hall measurements reveal a T-independent regime above 150 K and a strong thermally-activated regime below 150 K. These two phenomena are reminiscent of the behavior of n- type AlGaAs, suggesting the presence of similar N-induced DX- center-like states in GaAsN. We will discuss the dependence of these energies on both N composition and annealing temperature. \\[4pt] [1] Y. Jin \emph{et al.}, Appl. Phys. Lett. 95, 092109 (2009).\\[0pt] [2] Y. Jin \emph{et al.}, Appl. Phys. Lett. 95, 062109 (2009).