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

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 SiO x film significantly decreases from 2 to 1.2 as the substrate temperature increases from 200 to 400°C, corresponding to the enhanced precipitation of Si nanocrystals in the Si-rich SiOx. In comparison with stoichiometric SiO2, the Si-L2,3 transition induced kinetic energy loss of the primary electron transmitted through the Si-rich SiOx sample grown at 400°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°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/SiO x/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. © IOP Publishing Ltd.