Simple way of finding Ba to Si deposition rate ratios for high photoresponsivity in BaSi2 films by Raman spectroscopy

Since the photoresponsivity of BaSi2 is sensitive to a Ba-to-Si deposition rate ratio (RBa/RSi), there is a need to determine the optimum value of RBa/RSi. We grew 0.5 m thick BaSi2 films with RBa/RSi varied from 1.1-3.6 at 580 °C and 0.4-4.7 at 650 °C. The photoresponsivity reached a maximum at RBa/RSi = 2.2 and 1.2, respectively. Raman spectroscopy revealed that the crystalline quality of BaSi2 became better with decreasing RBa/RSi. However, as RBa/RSi decreased further beyond these values, excess Si precipitated, showing that the optimum value of RBa/RSi should be as small as possible without causing Si precipitates to form.