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

Abstract

Low-plasma and high-temperature chemical vapor deposition of Si-richSiOx for concurrently enhancing the carrier tunneling and light emission efficiency is investigated. TheO/Si compositionratio of the SiOx film significantly decreases from 2 to 1.2 as the substrate temperature increases from 200 to400 °C, corresponding to the enhanced precipitation of Si nanocrystals in the Si-richSiOx. In comparisonwith stoichiometric SiO2, the Si-L2,3 transition induced kinetic energy loss of the primary electron transmitted through the Si-richSiOx samplegrown at 400 °C is red-shifted by 5 eV. The strongest Si nanocrystal related photoluminescence (PL) can be obtained fromthe Si-rich SiOx film prepared at a threshold plasma power of 30 W and substrate temperature of400 °C. In low-plasma and high-temperature deposited samples, the thresholdFowler–Nordheim (F–N) tunneling field and the indium tin oxide(ITO)-SiOx junction potentialbarrier height of ITO/SiOx /p-Si/Al metal-oxide-semiconductor light emitting diodes (MOSLEDs) are concurrentlyreduced due to the increasing density of Si nanocrystals precipitated within theSiOx matrix. A thermal activation energy of 0.8 eV was observed for initiating the F–Ntunneling process in the MOSLEDs. The electroluminescence (EL) intensity andefficiency of the MOSLEDs are improved by at least 10 dB due to the oxygendeficient plasma enhanced chemical vapor deposition (PECVD) of Si-richSiOx at low plasma power and high temperatures.