Formation byLaser Impact of COnducting #beta#-Ga_2O_3-In_2O_2 sOLID sOLUTIONS WITH cOMPOSITION gRADIENTS

摘要

Solid solutions of #beta#-Ga_(2-zx)In_(2x)O_3 (x<-0.4) with #beta#-gallia struc-ture were investigated by Raman spectroscopy. A continuous evolution with a linear shift of the Raman lines with increasing x was observed in the existence range of the solid solution (x<-0.4). For 0.4<-x<- 0.5, strong alterations of the Raman spectra were observed, corresponding either to the demixing of the solid solutions for the samples elaborated at 1400 deg C or to the occurrence of a new phase with x-alumina structure for samples elaborated at 1550 deg C. The in situ formation of the #beta#-Ga_(2-2x). In_(2x)O_3 coiiipounds under laser irradiation could also be followed by Raman spectroscopy. Strong local variations of composition caused by a heterogeneous loss of indium could be detected inside the irradiated areas. In addition electron paramagnetic reson-ance revealed the existence of conduction electrons in these areas, resulting from a slight oxygen deficiency. These gradients of composition induce a spatial variation of the band gap and of the position of the Fermi level with respect to the conduction band so that the system is equivalent to an intrinsic-type junction.