ELECTROLUMINESCENCE CHARACTERISTICS AND CURRENT-CONDUCTION MECHANISM OF A SI-C-H-P-I-N THIN-FILM LIGHT-EMITTING-DIODES WITH BARRIER LAYER INSERTED AT P-I INTERFACE

Abstract

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.