Indium doping effect on properties of ZnO nanoparticles synthesized by sol–gel method
Mourad S1, El Ghoul J1, 2, †, Omri K1, Khirouni K1
       

Plot of ( α h ν ) 2 versus photon energy (hν), with spectra of first derivative of reflectance of In4%–ZO nanoparticles as shown in the inset.