Photodetectors based on intersubband transitions using III-nitride superlattice structures

Abstract

We review our recent progress on the fabrication of near-infrared photodetectors based on intersubband transitions in AlN/GaN superlattice structures. Such devices were first demonstrated in 2003, and have since then seen a quite substantial development both in terms of detector responsivity and high speed operation. Nowadays, the most impressive results include characterization up to 3 GHz using a directly modulated semiconductor laser and up to 13.3 GHz using an ultra-short pulse solid state laser.

Intersubband Transition-Based Processes and Devices in AlN/GaN-Based Heterostructures

“…The AFM analysis showed a root-mean-square surface roughness of about 0.6 nm in an area of 2.5 Â 2.5 "m 2 . From the analysis of the TEM picture, we concluded that the AlN/ GaN interfaces are abrupt at the monolayer scale [36].…”

Intersubband transition based efficient photovoltaic energy conversion

“…But uncertainty in material parameters, the lattice mismatch between AlN and GaN, the relaxation peculiarities of wurtzite nitride materials, and the presence of internal pyro-and piezo-electric fields make the simulation of this system only a design guideline but not any kind of valid confirmation of the energy eigen values i.e. absorption spectra [11].…”

Intersubband absorption properties of high Al content Al x Ga1−xN/GaN multiple quantum wells grown with different interlayers by metal organic chemical vapor deposition

“…AlGaN/GaN multiple quantum well (MQW) structures grown on GaN/sapphire templates (GaN templates) have attracted much interest for intersubband (ISB) transition devices operating in the near-infrared and mid-infrared spectral ranges, such as photovoltaic and photoconductive GaN/AlN quantum well (QW) detectors [1] and electrooptical modulators [2], benefiting from the large conduction-band offset (1.75 eV) between GaN and AlN. In addition, material transparency in a wide spectral region (360 nm to 13μm for GaN) [3], large longitudinal-optical phonon energy (92 meV for GaN), and the rather heavy-electron effective mass (0.22 × m 0 for GaN) also guarantee the realization of ISB transitions at room temperature.…”