Probing the relationship between structural and optical properties of Si-doped AlN

Much efforts have been devoted to achieve conductivity control in the ultrahigh band gap (similar to 6.1 eV) AlN by Si doping. The effects of Si-doping on the structural and optical properties of AlN epilayers have been investigated. X-ray diffraction studies revealed that accumulation of tensile stress in Si-doped AlN is a reason for the formation of additional edge dislocations. Photoluminescence (PL) studies revealed that the linewidths of both band-edge and impurity related transitions are directly correlated with the density of screw dislocations, N-screw, which increases with the Si doping concentration (N-Si). Furthermore, it was formulated that the band-edge (impurity) PL emission linewidth increases linearly with increasing N-screw at a rate of similar to 3.3 +/- 0.7 meV/10(8) cm(-2) (26.5 +/- 4 meV/10(8) cm(-2)), thereby establishing PL measurement as a simple and effective method to estimate screw dislocation density in AlN epilayers.