NIR resonant-cavity-enhanced InP/InGaAs strained quantum well interband photodetector

摘要

We demonstrate NIR (1.8 micrometer - 2.3 micrometer) resonant photo-detectors based on inter-band (Ecl-Ehhl) absorption in strain compensated, indium rich, InGaAs quantum wells (QW). Extremely low room temperature dark current densities are achieved by reduction of the active layer thickness combined with low defect density of the pseudomorphic strain compensated QWs. The weak absorption of the QW is enhanced by embedding the quantum well into a vertical resonant cavity. We present the experimental results for a demonstrator designed for a wavelength of 2 micrometer. The device, based on a single In$-0.83$/Ga$-0.17$/As quantum well and tensile strained barriers for strain compensation, exhibits a selectivity of 9 nm and 18% quantum efficiency. InP/InGaAs and Si/SiO$-2$/ material systems are used for the bottom and top distributed Bragg reflectors (DBR) of the cavity, with 20 pairs and 2 pairs respectively. The semiconductor structure is grown by MOCVD. The top Si/SiO$-2$/ DBR is deposited after fabrication of p-i-n planar photodiodes. Typical dark current densities are lower than 10$+$MIN@7$/ A/cm$+2$/ at $MIN@2 V bias. Conditions for extension of the operating wavelength up to 2.3 micrometer have been obtained experimentally using InAs/GaAs superlattice deposition to increase the thickness of the strained QW. A prospective tunable detector based on an actuable micro-machined air cavity and air/InP bottom DBR is proposed.