Enhanced ultraviolet photoluminescence from SiO2/Ge : SiO2/SiO2 sandwichedstructure

SiO2/Ge:SiO2/SiO2 sandwiched structure was fabricated for exploring efficie nt light emission. After annealed in N-2 (O-2<1%), this structure shows thr ee photoluminescence (PL) bands at 293, 395, and 780 nm. The intensity of t he 395 nm band is largely enhanced in comparison with that from the monolay ered Ge:SiO2 film. Spectral analyses suggest that the three PL bands origin ate from S-1-->S-0, T-Sigma(T-Pi)-->S-0, and T-Pi'-->S-0 optical transition s in GeO color centers, respectively. The improvement of the GeO density re sulting from the confinement on Ge diffusion is responsible for the enhance d ultraviolet PL. This structure is expected to have important applications in optoelectronics. (C) 2000 American Institute of Physics. [S0003-6951(00 )01446-7].