ABSTRACT
In this paper, semi-polar (20[Formula: see text]1) InGaN blue light-emitting diodes (LEDs) were fabricated and compared the performance with those of LEDs grown on c-plane sapphire substrate. LEDs with different chip sizes of 100 µm × 100 µm, 75 µm × 75 µm, 25 µm × 25 µm, and 10 µm × 10 µm were used to study the influence of chip size on the device performance. It was found that the contact behavior between the n electrode and the n-GaN layer for the semi-polar (20[Formula: see text]1) LEDs was different from that for the LEDs grown on the c-plane device. Concerning the device performance, the smaller LEDs provided a larger current density under the same voltage and presented a smaller forward voltage. However, the sidewall's larger surface to volume ratio could affect the IQE. Therefore, the output power density reached the maximum with the 25 µm × 25 µm chip case. In addition, the low blue-shift phenomenon of semi-polar (20[Formula: see text]1) LEDs was obtained. The larger devices exhibited the maximum IQE at a lower current density than the smaller devices, and the IQE had a larger droop as the current density increased for the LEDs grown on c-plane sapphire substrate.
