The effect of δ-doping and modulation-doping on Si-doped high Al content n-Alx Ga1-x N 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 5-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 asδ-doped n-Al0.55Ga0.45N.