Investigations on Electro-Optical and Photoelectric Detection Performance of GaN-Based micro-LEDs by Removing p-AlGaN Electron-Blocking Layer

Polarization effects introduced by the electron-blocking layer (EBL) in InGaN-based micro light-emitting diodes (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs) have a significant impact on their display and detection applications. Therefore, the impact and necessity of EBL structure for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED devices intended for such applications need to be reassessed. This article investigates the effect of removing p-AlGaN EBL structure on the performance of blue <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs when used as light-emitting devices under low-current injection and photodetectors (PDs). Luminescence efficiency and color stability of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED without EBL improve under low-current injection due to weakened polarization-induced band-bending and enhanced hole injection and electron confinement, as numerical simulations show. For photodetection applications, removing EBL reduces the photogenerated carrier escape barrier, improving the responsivity and bandwidth of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED PDs. Additionally, anomalous responsivities, dependent on bias and excitation energy, were observed in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED PDs with EBL. These observations can be elucidated by the trap-assisted tunneling (TAT) mechanism.