Leakage currents of large area InP/InGaAs heterostructures

Light-emitting diodes (LEDs) based on the conventional III-V compound semiconductors are known to exhibit internal quantum efficiencies (IQE) that are very close to unity. Ideally, the high IQE is expected to enable electroluminescent cooling with a cooling capacity of several Watts per cm ² of emitter area. One key requirement in enabling such cooling is the ability to fabricate high quality large area LEDs. However, detailed information on the performance of relevant large area devices and their yield is extremely scarce. In this report we present data on the yield and related large area scaling of InP/InGaAs LEDs by using current-voltage measurements performed on LED wafers fabricated at five different facilities. The samples were processed to contain square shaped mesas of sizes 0.25 mm² and 16 mm² operating as LEDs. While most of the smaller mesas showed relatively good electrical characteristics and low leakage current densities, some of them also exhibited very large leakage currents. In addition, in some cases the large area devices exhibited large, and even almost linearly behaving leakage currents. Such information on the scaling and unidealities of diodes fabricated using established fabrication technologies is crucial for the development of the optical cooling technologies relying on large area devices.