Efficient tunable luminescence of SiGe alloy sheet polymers

Crystalline SiGe alloy sheet polymers were topotactically prepared from epi taxially grown calcium germanosilicide Ca(Si1-xGex)(2) precursor films in t he whole composition range. These polygermanosilynes are found to be a well -defined mixture of the known siloxene and polygermyne sheet polymers with the OH groups exclusively bonded to silicon. The optical properties determi ned by photoluminescence and optical reflection measurements identify the m ixed SiGe sheet polymers as direct semiconductors with efficient luminescen ce tunable in the energy range between 2.4 and 1.3 eV. (C) 2001 American In stitute of Physics.