Rare Earth Doped Metal-Oxide-Semiconductor Structures: A Promising Material System or a Dead End of Optoelectronic Evolution?

The suitability of rare earth doped metal-oxide-semiconductor structures for optoelectronic applications is investigated. To do so, several Tb- and Er-doped devices with different designs and fabricated by different methods are compared among each other with respect to their electroluminescence (EL) properties. In detail, the investigated devices show EL power efficiencies between 2x10(-4) and 2x10(-3) which, taken individually for Tb and Er, have a linear dependence on the EL decay time for low and medium injection current densities. The excited fraction of Er ions is significantly higher than that of Tb ions and achieves a maximum value of 50% (with a maximum uncertainty factor of 2.25) under optimum conditions.