Effects of various hydrogen‐passivation techniques on the performance of a‐SiC:H‐based p‐i‐n ‐type thin‐film visible‐light‐emitting diodes

— The effects of various hydrogen‐passivation processes on the performance of a‐SiC:H‐based p‐i‐n ‐type thin‐film visible‐light‐emitting diodes (TFLEDs) fabricated by a photo‐CVD method have been investigated. A hydrogen‐passivation process was performed by three methods: in‐situ hydrogen passivation by a photo‐CVD method, ex‐situ hydrogen passivation via a plasma, and two‐step hydrogen passivation in which the in‐situ hydrogen‐passivation process was followed by an ex‐situ one. It was found that a hydrogen‐passivation process remarkably improved the device performance and that the two‐step hydrogen‐passivation process was most effective; i.e. , decrease of the threshold voltage by about 2 V, shift of the EL peak wavelength from 700 to 590 nm, and increase of the luminance up to 128 cd/m 2 ; and that improvement of the device performance by the hydrogen‐passivation process was dominantly caused by a decrease of midgap states by hydrogen atoms.