Electroluminescence characteristics and current-conduction mechanism of a-SiC:H p-i-n thin-film light-emitting diodes with barrier layer inserted at p-i interface

In order to improve the electroluminescence (EL) characteristics of the hydrogenated amorphous silicon carbide (a-SiC:H) p-i-n thin-film light-emitting diode (TFLED), a barrier layer (BL) was inserted at its p-i interface to enhance the hole injection efficiency under forward-bias operation. The a-SiC:H TFLED´s with various optical gaps of BL had been fabricated and characterized. In addition, a composition-graded n⁺-layer was used to reduce its series and contact resistances to the Al electrode and hence the EL threshold voltage (V_th) of an a-SiC:H BL TFLED. The highest obtainable brightness of an a-SiC:H BL TFLED was 342 cd/m² at an injection current density of 600 mA/cm² and the lowest EL V _th achievable was 6.0 V. The current-conduction mechanism of an a-SiC:H BL TFLED had also been investigated. Within the lower applied-bias region, it showed an ohmic current, while within the higher applied-bias region, a space-charge-limited current (SCLC) was observed