Free-standing GaN substrates were of great importance for short wavelength laser diodes and high performance light emitting diode applications. One of the technical barriers for the applications was relatively high threading dislocation density in GaN substrates known as non-radiative centers. The influence of threading dislocation density upon Hall effects in Si-doped GaN free-standing substrates, grown by hydride vapor-phase epitaxy, was analyzed here. To verify the role of threading dislocations as deep acceptor level and carrier scattering lines, active carrier concentration and Si doping concentration [nSi] of each GaN substrate were compared for various DD. In addition, O doping concentration [nO] of unintentionally doped GaN substrate that had similar dislocation densities to the Si-doped GaN substrate were measured in order to consider the influence of doped O known as main background impurity, and the Hall characteristics of unintentionally doped GaN were compared with that of the Si-doped GaN. From the results, it was experimentally postulated that threading dislocations functioned as trap centers; disturbing the movement of n-carriers in GaN substrates.

The Influence of Threading Dislocation Density on Hall Effects in Free-Standing GaN Substrates. C.Lee, H.Y.Lee, H.Shin, C.Kim, H.Ko, J.Han, H.Kim, K.Lee: Physica Status Solidi C, 2005, 2[7], 2137-40