Observation of extremely high current densities on order of MA/cm ² 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 μm² 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 μm² on a silicon substrate exhibits an extremely high current density of 6,350,000 A/cm² 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 ot current densities between nA/cm ² and MA/cm².