Tunable hot-carrier photodetection beyond the bandgap spectral limit

The spectral response of common optoelectronic photodetectors is restricted by a cutoff wavelength limit λ that is related to the activation energy (or bandgap) of the semiconductor structure (or material) (Δ) through the relationship λ = hc/Δ. This spectral rule dominates device design and intrinsically limits the long-wavelength response of a semiconductor photodetector. Here, we report a new, long-wavelength photodetection principle based on a hot-cold hole energy transfer mechanism that overcomes this spectral limit. Hot carriers injected into a semiconductor structure interact with cold carriers and excite them to higher energy states. This enables a very long-wavelength infrared response. In our experiments, we observe a response up to 55 μm, which is tunable by varying the degree of hot-hole injection, for a GaAs/AlGaAs sample with Δ = 0.32 eV (equivalent to 3.9 μm in wavelength)

Experimental study of hot electron inelastic scattering rate in p-type InGaAs

International audienceThe inelastic scattering rates of electrically injected minority hot electrons measured using a continuous-wave spatially resolved electroluminescence spectroscopy are reported. To our knowledge, this constitutes direct experimental determination of this parameter related to the individual inelastic interactions. The evolution of the electron relaxation rate with increasing majority hole density is explored. Remarkably, an attenuation of the scattering rate is measured for p-doping levels higher than 2×1019 cm-3. Additionally, the measured hot-electron energy distributions further indicate that the relaxation mechanisms are dominated by LO phonon-plasmons coupled modes in the range 1018 to 1019 cm-3 hole density. Finally, the temperature dependence of inelastic scattering rate is also measured to learn on the potential implication of ballistic transport in RT operating hot-electron devices