Characterization of Fe-doped semi-insulating InP by low temperature and room temperature spatially resolved photoluminescence

Abstract

Scanning photoluminescence has been used to characterize four 2 inch (100) wafers cut from the same Fe-doped semi-insulating LEC 〈111〉 InP ingot. The photoluminescence mappings have been done both at room temperature and at low ( ̃ 10 K) temperature. In the latter case, scannings have been performed with an optical resolution of 20 μm at two different energies: 1.417 and 1.380 eV. The highest energy corresponds to the band-to-band photoluminescence emission, while the lowest one is associated with the band-to-acceptor (in our case Zn and C) transition. Higher optical resolution ( ̃1 μm) has been also achieved at low temperature but without any energy selection. The photoluminescence data reveal substrate non-homogeneities which have been attributed to variation of Fe concentration. The images of the 2 inch wafers show clear growth striations as well as a central growth facet. At the microscopic scale, dislocations corresponding to bright photoluminescence dots have been identified. Higher dislocation density has been found along some of the growth striations. Areas exhibiting higher acceptor impurity concentration have been also detected. Finally, the resistivity mapping of the slice cut from the ingot under investigation show a direct correlation with the photoluminescence results.