On the behavior of the silicon donor in conductive AlxGa1-xN (0.63≤x≤1) layers

We have studied the silicon donor behavior in intentionally silicon doped AlxGa1-xN (0.63≤x≤1) grown by hot-wall metal-organic chemical vapor deposition. Efficient silicon doping was obtained for lower Al contents whereas the conductivity drastically reduces for AlGaN layers with Al content in the range x~0.84-1. Degradation of the structural quality and compensation by residual O and C impurities were ruled out as possible explanations for the reduced conductivity. By combining frequency dependent capacitance-voltage and electron paramagnetic resonance measurements we show that the Si donors are electrically active and that the reduced conductivity can be explained by the increased activation energy caused by the sharp deepening of the Si DX– state..
Swedish Research Council (VR); VR Linkoping Linnaeus Initiative for Novel Functional Materials (LiLi-NFM); Swedish Energy Agency; Knut and Alice Wallenberg Foundation (KAW); Swedish Governmental Agency for Innovation Systems (VINNOVA)