Enhanced Fowler-Nordheim tunneling effect in nanocrystallite Si based LED with interfacial Si nano-pyramids

The premier observation on the enhanced light emission from such a metal-SiOx-Si light emitting diode (MOSLED) with Si nano-pyramids at SiOx/Si interface is demonstrated at low biases. The Si nano-pyramids exhibits capability in providing the roughness of the SiOx/Si interface, and improving the Fowler-Nordheim (F-N) tunneling mechanism based carrier injection through the novel SiOx/nano-Si-pyramid/Si structure. HRTEM analysis reveals a precisely controllable size and concentration of the crystallized interfacial Si nano-pyramids at 10nm(height) x 10nm(width) and within the range of 10(8)-10(11) cm(-2), respectively. With these Si nano-pyramids at a surface density of up to 10(12)/cm(2), the F-N tunneling threshold can be reduce from 7 MV/cm to 1.4 MV/cm. The correlation between surface density of the interfacial Si nano-pyramids and the threshold F-N tunneling field has been elucidated. Such a turn-on reduction essentially provides a less damaged SiOx/Si interface as the required bias for the electroluminescence of the MOSLED is greatly decreased, which thus suppresses the generation of structural damage related radiant defects under a lower biased condition and leads to a more stable near-infrared electroluminescence with a narrowing linewidth and an operating lifetime lengthened to > 3 hours. An output EL power of nearly 150 nW under a biased voltage of 75 V and current density of 32 mA/cm(2) is reported for the first time. (c) 2007 Optical Society of America.