The effect of δ-doping and modulation-doping on Si-doped high Al content n-AlxGa1-xN grown by MOCVD

The effect of periodic delta-doping and modulation-doping on high Al content n-AlxGa1-xN (x= 0.55) epilayers grown by MOCVD has been investigated. Measured by XRD, AFM, contactless sheet resistance, and Hall-effect tests, δ-doped and modulation-doped n-AlxGa1-xN have better crystal quality, surface morphology and electrical properties as compared with uniformly-doped n-AlxGa1-xN. These improvements are attributed to the SiNx growth mask induced by δ-doping layers and the dislocation-blocking effect induced by both growth techniques. In addition, due to the broadened doping profile ascribed to enhanced dopant diffusion at high growth temperatures (1150 ℃) of n-Al0.55Ga0.45N, modulation-doped n-Al0.55Ga0.45N has similar properties as δ-doped n-Al0.55Ga0.45N.