Monolithically integrated UVC AlGaN-based multiple quantum wells structure and photonic chips for solar-blind communications

Abstract

High quality AlGaN material growth and chip fabrication of monolithically integrated solar blind light-emitting diodes (LEDs), waveguides and photodetectors (PDs) on an AlGaN multi-quantum wells (MQWs) wafer are presented. The strong light constraint of waveguides is confirmed, in virtue of predominant ultraviolet transverse magnetic (TM) modes in transverse transmission. Unaffected by the ambient lighting, the PDs demonstrate sufficient photosensitivity to the optical signal traveling along waveguides owing to the emission-responsion spectral overlap. When the LEDs are operated at 20 mA current, the photo-to-dark current ratio (PDCR) in the PDs is up to seven orders of magnitude, which is higher than previously reported values for self-driven nitride PDs. The responsivity, specific detectivity and external quantum efficiency (EQE) of self-driven PDs are 186 A/W, 2.54 × 1014 Jones and 8.4 × 104%, respectively. Benefiting from the effective optical isolation, the light crosstalk between adjacent devices is effectively reduced about 70%. The self-driven PDs exhibit 127/131 ns (rise/decay) rapid response in the on-chip communication. This work opens a pathway to drastically improve the ultraviolet-C (UVC) monolithically integrated systems and extends the fields of application in solar-blind communication.