Quantitative determination of depth carrier profiles in ion-implanted Gallium Nitride

We studied the electrical activation of Si+ ions implanted at multiple energies (80 and 180 keV) and with a total fluence up to 2.7 x 10(14) CM-2 in heteroepitaxial GaN films on sapphire. Calibrated scanning capacitance microscopy- (SCM) is proposed as a method to measure the depth carrier profile after high temperature annealing (1100 1200 degrees C). Si electrically active fractions of 18% and 36% were obtained after low ramp rate furnace annealing at 1100 and 1200 degrees C, respectively. Interestingly, the dopant activation was significantly improved to 63% in the case of a rapid pre-annealing process at 1100 degrees C before the 1200 degrees C furnace annealing process. Furthermore, the ionised carrier fluence obtained by Hall measurements at room temperature exhibits a significant improvement for the 1100 degrees C RTA preannealed sample. This value is in good agreement with the ionised fluence calculated from the active Si profile from SCM, considering a similar to 20 meV ionisation energy for Si donors in GaN. (c) 2007 Elsevier B.V. All rights reserved.