Zn channeled implantation in GaN: damages investigated by using high resolution XTEM and channeling RBS

Zn (140 keV) channeled (along [0001]) implantations in GaN are performed at room temperature and in a dose range from 1 x 10(13) to 4 x 10(16) Cm-2, respectively. Channeling RBS measurements and the high-resolution XTEM investigations show the two damage regimes after implantation: one at the surface and another in the projected range. The damage level is very small at low doses and then gradually rises with increasing dose. The backscattering yield from the near surface region reaches the random level at doses higher than 2 x 10(16) cm(-2) and the broken crystals and the amorphous in nanometer size are formed in the top thin surface layer after implantation at a dose of 3 x 10(16) Cm-2. In the followed defective crystalline layer, the density of defects decreases with increasing the depth. The thread defects and loops are dominant in the region close to the surface at high dose and the clustered point defects are dominant in the deeper layer. (C) 2002 Elsevier Science B.V. All rights reserved.