Photoluminescence and photoresponse properties of aluminum doped β-FeSi2

Orthorhombic FeSi₂ (β-FeSi₂) has been known as one of promising semiconductors for Si monolithic photonics circuits. β-FeSi₂ shows clear light emission and photoresponse near 1.55 μm in wavelength and a high refractive index (>5.8) (Lange, 1997). These basic optical properties are appropriate to Si optoelectronic integrated circuits (Si-OEIC) consisting of Si waveguides being a crucial technology for monolithic fabrication. The monolithic fabrication of 1.55 μm-light emitting diodes and IR-photodetectors (Maeda, 2000) connected effectively with the Si waveguide can be made possibly by conventional fine ion beam synthesis (IBS) procedures of β-FeSi₂. However, detailed mechanism of optical processes in β-FeSi₂ has not been well understood. In order to obtain more intense 1.55 μm-emission and high sensitivity, an advanced technology for improvement of optoelectronics performance should be required. In this work, we have found pronounced effects of the Al-doping into β-FeSi₂/Si heterostructures on the light emission and photovoltaic properties.