Observation of Extremely High Current Densities on Order of MA/cm² in Copper Phthalocyanine Thin-Film Devices with Submicron Active Areas

Using contact photolithography and electron-beam lithography techniques, we manufactured copper phthalocyanine thin-film devices with active areas ranging from 1,000,000 to 0.04 µm 2 to investigate how much current can flow through these devices with the aim of fabricating electrically pumped organic laser diodes. From the results of our current density–voltage ( J – V ) measurements, we found that the device with the smallest active area of 0.04 µm 2 on a silicon substrate exhibits an extremely high current density of 6,350,000 A/cm 2 due to improved thermal management. The J – V characteristics of the devices are controlled by shallow-trap space-charge-limited current (SCLC), trap-free SCLC, and two-carrier injection current mechanisms over a wide range of current densities between nA/cm 2 and MA/cm 2 .