Influence of fabrication steps on optical and electrical properties of InN thin films

This paper reports on a case study of the impact of fabrication steps on InN material properties. We discuss the influence of annealing time and sequence of device processing steps. Photoluminescence (PL), surface morphology and electrical transport (electrical resistivity and low frequency noise) properties have been studied as responses to the adopted fabrication steps. Surface morphology has a strong correlation with annealing times, while sequences of fabrication steps do not appear to be influential. In contrast, the optical and electrical properties demonstrate correlation with both etching and thermal annealing. For all the studied samples PL peaks were in the vicinity of 0.7 eV, but the intensity and full width at half maximum (FWHM) demonstrate a dependence on the technological steps followed. Sheet resistance and electrical resistivity seem to be lower in the case of high defect introduction due to both etching and thermal treatments. The same effect is revealed through 1/f noise level measurements. A reduction of electrical resistivity is connected to an increase in 1/f noise level.