Space and Time Domain Transport Modulation by InGaN/GaN Single-Carrier Superlattices for High-Performance UV-Blue Photodetection

Abstract

The use of mainstream Si-photodetectors (PDs) and other developing PDs is seriously limited in emerging applications because they struggle to achieve high sensitivity, high speed, and strong wavelength selectivity simultaneously. Here, we present UV-blue photodetectors combining these key advantages by modulating the carrier localization and carrier lifetime in the InGaN/GaN material system. The photodetectors incorporate an active region consisting of a polarization heterojunction barrier and single-carrier superlattices (SCSLs). The polarization field within the SCSLs/GaN heterojunction induces the hole localization of space, enabling low dark current and high gain due to a photoinduced barrier lowering effect, while the designed InGaN/GaN SCSLs allow the photoelectrons in the quantum wells to escape but slightly localize the photogenerated holes, resulting in a nondefect-related controllable photoconductive gain from the lifetime modulation. By introducing the spatial localization and lifetime controlling of photogenerated carriers, the fabricated devices exhibited an ultrahigh responsivity of up to 1.8 × 10⁶ A/W at 402 nm and a fast impulse response speed with a rise/falling time of 2.65/82.7 ns. In addition, a sharp cutoff with a 430/450 nm rejection ratio of more than 10⁵ was demonstrated at 1 V, indicating excellent wavelength selectivity. These metrics are comparable to or even better than Si avalanche photodiodes within the corresponding spectral range, providing feasible choices for applications such as visible light communication with requirements in detectivity, speed, and wavelength selectivity.