Low-plasma and high-temperature PECVD grown silicon-rich SiOx film with enhanced carrier tunneling and light emission

摘要

Low-plasma and high-temperature chemical vapor deposition of Si-rich SiOx for concurrently enhancing the carrier tunneling and light emission efficiency is investigated. The O/ Si composition ratio of the SiOx film significantly decreases from 2 to 1.2 as the substrate temperature increases from 200 to 400 degrees C, corresponding to the enhanced precipitation of Si nanocrystals in the Si- rich SiOx. In comparison with stoichiometric SiO2, the Si- L-2,L-3 transition induced kinetic energy loss of the primary electron transmitted through the Si-rich SiOx sample grown at 400 degrees C is red-shifted by 5 eV. The strongest Si nanocrystal related photoluminescence ( PL) can be obtained from the Si- rich SiOx film prepared at a threshold plasma power of 30 W and substrate temperature of 400 degrees C. In low-plasma and high-temperature deposited samples, the threshold Fowler - Nordheim ( F - N) tunneling field and the indium tin oxide ( ITO)- SiOx junction potential barrier height of ITO/ SiOx /p-Si/Al metal-oxide-semiconductor light emitting diodes ( MOSLEDs) are concurrently reduced due to the increasing density of Si nanocrystals precipitated within the SiOx matrix. A thermal activation energy of 0.8 eV was observed for initiating the F - N tunneling process in the MOSLEDs. The electroluminescence ( EL) intensity and efficiency of the MOSLEDs are improved by at least 10 dB due to the oxygen deficient plasma enhanced chemical vapor deposition ( PECVD) of Si- rich SiOx at low plasma power and high temperatures.