Page - 152 - in Photovoltaic Materials and Electronic Devices

5 5  2.911  10.0845  –  14  8  2.908  10.0764  –  19  3.1.2.  AFM  Analysis  Figure  2  shows  the  AFM  surface  topology  of  the  ITO  films  deposited  under  three  different  oxygen  environments  and  etched  for  1  min  and  8  min.      Figure  2.  Surface  topology  image  for  2  μm  ×  2  μm  ×  0.2  μm  of  the  ITO  film  deposited  under  various  oxygen  environments:  (A)  0  sccm  oxygen,  (B)  0.4  sccm  oxygen,  (C)  1.0  sccm  oxygen,  and  etched  for    8  min,  (D)  0  sccm  oxygen,  (E)  0.4  sccm  oxygen  and  (F)  1  sccm  oxygen.  (A–C)  etched  for  1  min  and    (D–F)  films  etched  for  8  min.  The  etching  was  performed  at  room  temperature.    Figure 2. Surface topology image for 2µ ˆ 2µmˆ 0.2µm of the ITO film deposited under various oxygen environments: (A) 0 sccm oxygen; (B) 0.4 sccm oxygen; (C) 1.0 sccm oxygen, and etched for 8 min; (D) 0 sccm oxygen; (E) 0.4 sccm oxygenand(F)1sccmoxygen. (A–C) etchedfor1minand(D–F)filmsetchedfor 8min. Theetchingwasperformedat roomtemperature. Figure 2A,B shows the ITO films deposited in an oxygen deficient ambient and etchedfor1and8min, respectively. Spherical sizedgrainsareclearlyvisible inall AFM images presented in Figure 2. There is variation of surface roughness of the filmswithbothoxygenflowrateandetchingtimeof the ITOfilms. Theminimum valueofsurfaceroughnessof0.65nmwasmeasuredfor ITOfilmssputteredusing 0.4sccmoxygenflowrateandetchedfor1min,whileamaximumsurfaceroughness valueof8.9nmwasobservedforfilmsprocessedat1.0sccmoxygenflowrateand etchedfor1min. Therewasaslight increaseinroughnesswithetchingtimeobserved for 0 sccm and 0.4 sccm ITO film, for etching times 1 min to 8 min. However, the 1.0sccmfilms, showedthegreatestvariation insurfaceroughnessevenafter1min etchingprocess. Generally, thesurfaceroughnessofthefilmsareobservedtoincrease whentheoxygengasconcentration is increasedduringprocessing. 3.1.3. RamanSpectroscopy Figure 3 shows the Raman spectrum for ITO deposited at various oxygen compositionsandetchedat1,3,5and8minrespectively. Ramanspectroscopyisused todetermine the structural conformationsof thematerials. Grouptheorypredicts 152