Formation by laser impact of conducting β-Ga2O3-In2O3 solid solutions with composition gradients

Abstract Solid solutions of β -Ga 2−2 x In 2 x O 3 ( x ≤0.4) with β -gallia structure 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°C or to the occurrence of a new phase with κ -alumina structure for samples elaborated at 1550°C. The in situ formation of the β -Ga 2−2 x In 2 x O 3 compounds 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 resonance 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/ n -type junction.