Raman And Photoluminescence Analysis Of Cd 1-x Mn x Te Thin Films

ABSTRACT 1-xx films (thickness -0.5 micron, x = 0.10 - 0.37) have been grown by metalorganic chemical vapor deposition on commercial GaAs and glass substrates with and without buffer layers of CdTe and CdS for potential use in solar cells. Raman scattering and photolumi- nescence played an important role in characterizing and optimizing film quality. Raman methods established the relation between film quality and substrate type or growth temperature. Photoluminescence spectroscopy determined the percent of Mn in the as-grown films, dis­ played stress effects due to lattice mismatch and their dependence on substrate, and indicated the presence of defects. INTRODUCTION Much effort has been invested in dilute magnetic semiconductors like Cc*i_xMnxTe (CMT) , with their novel and potentially useful elec­ tronic and magnetic properties.1' 2 One possible application is in high-efficiency solar cells. Although CMT films and superlattices (SL) have been grown by molecular beam epitaxy (MBE)4""8, there has been little growth and analysis of low-cost CMT films made on com­ mercial wafers9 for wide use. This paper shows how Raman and photolu- minescence (PL) spectroscopy play a significant role in developing MCT grown by metalorganic chemical vapor deposition (MOCVD). These optical methods optimize growth conditions and determine the quality of CMT films with Mn fraction x = 0.1 - 0.37, grown on commercial GaAs and glass wafers.