Cavity-enhanced AlGaAs/GaAs resonant tunneling photodetectors for telecommunication wavelength light detection at 1.3 μm

摘要

We demonstrate a cavity-enhanced photodetector at the telecommunication wavelength of λ= 1.3 μm based on a resonant tunneling diode (RTD). The cavity-enhanced RTD photodetector consists of three integral parts: First, a Ga_(0.89)In_(0.11)N_(0.04)As_(0.96) absorption layer that can be grown lattice-matched on GaAs and which is light-active in the near infrared spectral region due to its reduced bandgap energy. Second, an Al_(0.6)Ga_(0.4)As/GaAs double barrier resonant tunneling structure (RTS) that serves as high gain internal amplifier of weak electric signals caused by photogenerated electron-hole pairs within the GaInNAs absorption layer. Third, an optical distributed Bragg reflector (DBR) cavity consisting of five top and seven bottom alternating GaAs/AlAs mirror pairs, which provides an enhanced quantum efficiency at the resonance wavelength. The samples were grown by molecular beam epitaxy. Electro-optical properties of the RTDs were studied at room temperature. From the reflection-spectrum the optical resonance at λ = 1.29 urn was extracted. The current-voltage characteristics were studied in the dark and under illumination and a well-pronounced photo-response was found and is attributed to accumulation of photogenerated holes in the vicinity of the RTS. The maximum photocurrent was found at the optical resonance of 1.29 urn. At resonance, a sensitivity of S = 3.97 × 10~4 A/W was observed. From the sensitivity, a noise-equivalent power of NEP = 1.18 × 10~(-16) W/Hz~(1/2), and a specific detectivity of D~* (=) 6.74 × 10~(12) cm Hz~(1/2)/W were calculated. For a single absorbed photon a photocurrent of I_(SP) = 50 pA was determined.