A quantum cascade detector in the GaN/AlGaN/AlN material system was implemented. The design takes advantage of the large internal field existing in the nitrides in order to generate the essential saw tooth energy level structure. The device operates in the near IR spectral range with a room temperature responsivity at λ=1.7μm of 10mA∕W (1000V∕W) at zero bias. The spectroscopic measurements are in good agreement with simulations.
We fabricated a communication wavelength photodetector based on intraband transition in GaN∕AlN self-assembled quantum dot heterostructures. The quantum dot photodetector is based on in-plane transport and has a room temperature spectral peak responsivity of 8mA∕W at wavelength of 1.41μm. We use multipass waveguide geometry to show that the polarization sensitive optical absorption spectrum of the heterostructure is nearly the same as its photocurrent spectral response. This establishes that the detector’s response is due to the presence of quantum dots in its active layer. We use photoluminescence, transmission, and intraband photocurrent spectroscopy to consistently describe the alignment between the energy levels of the quantum dots and that of the wetting layer.
We demonstrate intersuband InGaN/(Al)GaN quantum well infrared photodetectors grown on a free standing non-polar m-plane GaN substrate. The devices are grown by metal organic chemical vapor deposition and exhibit TM-polarized photocurrent at peak wavelengths of 7.5 and 9.3 μm at temperature of 14 K. Based on the experimental data of intersubband and interband transition energies and 8-band k · p Schrödinger-Poisson solver calculations, we were able to estimate the conduction band offset to valence band offset discontinuity ratio (ΔEc:ΔEv) of 57:43 for In0.1Ga0.9N/GaN and 55:45, for In0.095GA0.905N/Al0.07Ga0.93N non-polar m-plane multi-quantum well structures.
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